Search

Nowadays, exploring new photonic materials that can efficiently convert the invisible light into the visible light have attracted tremendous attention in the catalytic field. Here, we design and prepare a kind of Bi 3+ doped Lu 2 CaGeO 6 phosphor by using the solid-state reaction at 1250 °C in air for 5 h. The structural analysis, which is based mainly on the powder X-ray diffraction (XRD) spectra, shows that the as-prepared Bi 3+ doped Lu 2 CaGeO 6 phosphors belong to a trigonal structure with a space group of R 3 (No. 146). The photoluminescence (PL) results reveal that changing the excitation wavelengths from 240 nm to 340 nm does not change the emission sharp and position of the Bi 3+ doped samples, allowing the maximum emission intensity to keep at 420 nm. Except for the fluorescence, up exposure to the UV light ( e.g. , 254 nm), the Lu 2 CaGeO 6 :Bi 3+ phosphors can also exhibit the Bi 3+ -related blue afterglow luminescence. The longest afterglow duration that corresponds to the 1.5%Bi 3+ doping content in the Lu 2 CaGeO 6 crystal host can last 30 min in the dark. After comparing the Bi 3+ -related blue afterglow band to the band gap of TiO 2 semiconductor that corresponds to the wavelength of 387 nm, it clearly indicates us that the Bi 3+ doped Lu 2 CaGeO 6 phosphors can serve as a continous excitation source for light-sensitive TiO 2 semiconductor for photocatalysis application. [ABSTRACT FROM AUTHOR]

Bardoxolone methyl, a synthetic triterpenoid, improves the estimated glomerular filtration rate (GFR) in patients with chronic kidney disease and type 2 diabetes. Since the contractile activity of mesangial cells may influence glomerular filtration, we evaluated the effect of the synthetic triterpenoid RTA 405, with structural similarity to bardoxolone methyl, on GFR in rats and on mesangial cell contractility in freshly isolated glomeruli. In rats, RTA 405 increased basal GFR, assessed by inulin clearance, and attenuated the angiotensin II-induced decline in GFR. RTA 405 increased the filtration fraction, but did not affect arterial blood pressure or renal plasma flow. Glomeruli from RTA 405-treated rats were resistant to angiotensin II-induced volume reduction ex vivo. In cultured mesangial cells, angiotensin II-stimulated contraction was attenuated by RTA 405, in a dose- and time-dependent fashion. Further, Nrf2-targeted gene transcription (regulates antioxidant, anti-inflammatory, and cytoprotective responses) in mesangial cells was associated with decreased basal and reduced angiotensin II-stimulated hydrogen peroxide and calcium ion levels. These mechanisms contribute to the GFR increase that occurs following treatment with RTA 405 in rats and may underlie the effect of bardoxolone methyl on the estimated GFR in patients. [ABSTRACT FROM AUTHOR]

Activation of the sympathetic nervous system hastens the rate of progression and severity of chronic heart failure (CHF). Chemically sensitive nerves in the carotid body (CB) that stimulate sympathetic nerve activity become overly active in CHF and contribute to this phenomenon. The stimulus for activation of these CB chemoreceptors is not known. Blood supply to tissues is impaired due to the failing heart. In this study we tested whether a chronic reduction in blood flow to the CB may contribute to altered CB chemoreceptor function. The results show that changes that occur in CB chemoreceptor function during CHF are identical to those that occur if blood flow is simply reduced to the CB for several weeks. The results suggest that chronic impairment of blood flow may be the key step in the pathophysiological events that cause sympathetic nervous system activation in heart failure. [ABSTRACT FROM AUTHOR]

Slow-controlled release fertilizers are experiencing a popularity in rice cultivation due to their effectiveness in yield and quality with low environmental costs. However, the underlying mechanism by which these fertilizers regulate grain quality remains inadequately understood. This study investigated the effects of five fertilizer management practices on rice yield and quality in a two-year field experiment: CK, conventional fertilization, and four applications of slow-controlled release fertilizer (UF, urea formaldehyde; SCU, sulfur-coated urea; PCU, polymer-coated urea; BBF, controlled-release bulk blending fertilizer). In 2020 and 2021, the yields of UF and SCU groups showed significant decreases when compared to conventional fertilization, accompanied by a decline in nutritional quality. Additionally, PCU group exhibited poorer cooking and eating qualities. However, BBF group achieved increases in both yield (10.8 t hm−2 and 11.0 t hm−2) and grain quality reaching the level of CK group. The adequate nitrogen supply in PCU group during the grain-filling stage led to a greater capacity for the accumulation of proteins and amino acids in the PCU group compared to starch accumulation. Intriguingly, BBF group showed better carbon–nitrogen metabolism than that of PCU group. The optimal nitrogen supply present in BBF group suitable boosted the synthesis of amino acids involved in the glycolysis/ tricarboxylic acid cycle, thereby effectively coordinating carbon–nitrogen metabolism. The application of the new slow-controlled release fertilizer, BBF, is advantageous in regulating the carbon flow in the carbon–nitrogen metabolism to enhance rice quality. [ABSTRACT FROM AUTHOR]

Sucrose non-fermenting-1-related protein kinase 1 (SnRK1) and AMP-activated protein kinase (AMPK) are highly conserved. Compound 991 is an AMPK activator in mammals. However, whether 991 also activates SnRK1 remains unknown. The addition of 991 significantly increased SnRK1 activity in desalted extracts from germinating rice seeds in vitro. To determine whether 991 has biological activity, rice seeds were treated with different concentrations of 991. Germination was promoted at low concentrations but inhibited at high concentrations. The effects of 991 on germination were similar to those of OsSnRK1a overexpression. To explore whether 991 affects germination by specifically affecting SnRK1, germination of an snrk1a mutant and the wild type under 1 μM 991 treatment was compared. The snrk1a mutant was insensitive to 991. Phosphoproteomic analysis showed that the differential phosphopeptides induced by 991 and OsSnRK1a overexpression largely overlapped. Furthermore, SnRK1 might regulate rice germination in a dosage-dependent manner by regulating the phosphorylation of three phosphosites, namely S285-PIP2;4, S1013-SOS1, and S110-ABI5. These results indicate that 991 is a specific SnRK1 activator in rice. The promotion and inhibition of germination by 991 also occurred in wheat seeds. Thus, 991 is useful for exploring SnRK1 function and the chemical regulation of growth and development in crops. [ABSTRACT FROM AUTHOR]

Key message: Purine permease PUP11 is essential for rice seed development, regulates the seed setting rate, and influences the cytokinin content, sugar transport, and starch biosynthesis during grain development. The distribution of cytokinins in plant tissues determines plant growth and development and is regulated by several cytokinin transporters, including purine permease (PUP). Thirteen PUP genes have been identified within the rice genome; however, the functions of most of these genes remain poorly understood. We found that pup11 mutants showed extremely low seed setting rates and a unique filled seed distribution. Moreover, seed formation arrest in these mutants was associated with the disappearance of accumulated starch 10 days after flowering. PUP11 has two major transcripts with different expression patterns and subcellular locations, and further studies revealed that they have redundant positive roles in regulating the seed setting rate. We also found that type-A Response Regulator (RR) genes were upregulated in the developing grains of the pup11 mutant compared with those in the wild type. The results also showed that PUP11 altered the expression of several sucrose transporters and significantly upregulated certain starch biosynthesis genes. In summary, our results indicate that PUP11 influences the rice seed setting rate by regulating sucrose transport and starch accumulation during grain filling. This research provides new insights into the relationship between cytokinins and seed development, which may help improve cereal yield. [ABSTRACT FROM AUTHOR]

Melatonin mediates multiple physiological processes in plants and is involved in many reactions related to the protection of plants from abiotic stress. In this paper, the effect of melatonin on the antioxidant capacity of rice under salt stress was studied. Melatonin alleviated the inhibition of salt stress on the growth of rice seedlings, mainly by increasing the dry weight and fresh weight of shoots and roots. Melatonin alleviated the membrane damage caused by salt stress, which was mainly manifested by the decrease of TBARS content and the decrease of leaf and root damage. During the whole salt stress period, rice after melatonin pretreatment showed lower ROS (H 2 O 2 , O 2 •−,OH−) accumulation. In the early stage (1–3 d) of stress, the rice after melatonin pretreatment showed a strong increase in antioxidant enzyme activity, while in the later stage (5,7 d), it showed a strong increase in antioxidant content. During the whole period of salt stress, melatonin had a weak regulatory effect on AsA-GSH cycle. Through the above regulation process, the decreasing effect of melatonin on ROS content of rice under salt stress did not decrease with prolonged stress time in a short time (1-7 d). In conclusion, melatonin improved the antioxidant capacity of rice under continuous salt stress, and rice showed variable antioxidant strategies after melatonin pretreatment. • Salt stress resulted in continuous accumulation of ROS, and MT pretreatment alleviated the oxidative damage of rice. • MT regulates antioxidant strategy in response to continuous salt stress. • MT pretreatment improves salt tolerance of rice. [ABSTRACT FROM AUTHOR]

Background: The intensified global warming during grain filling deteriorated rice quality, in particular increasing the frequency of chalky grains which markedly impact market value. The formation of rice quality is a complex process influenced by multiple genes, proteins and physiological metabolic processes. Proteins responsive to stimulus can adjust the ability of plants to respond to unfavorable environments, which may be an important protein involved in the regulation of quality formation under elevated temperature. However, relatively few studies have hindered our further understanding of rice quality formation under elevated temperature. Results: We conducted the actual field elevated temperature experiment and performed proteomic analysis of rice grains at the early stage of grain filling. Starting with the response to stimulus in GO annotation, 22 key proteins responsive to stimulus were identified in the regulation of grain filling and response to elevated temperature. Among the proteins responsive to stimulus, during grain filling, an increased abundance of signal transduction and other stress response proteins, a decreased abundance of reactive oxygen species-related proteins, and an increased accumulation of storage substance metabolism proteins consistently contributed to grain filling. However, the abundance of probable indole-3-acetic acid-amido synthetase GH3.4, probable indole-3-acetic acid-amido synthetase GH3.8 and CBL-interacting protein kinase 9 belonged to signal transduction were inhibited under elevated temperature. In the reactive oxygen species-related protein, elevated temperature increased the accumulation of cationic peroxidase SPC4 and persulfide dioxygenase ETHE1 homolog to maintain normal physiological homeostasis. The increased abundance of alpha-amylase isozyme 3E and seed allergy protein RA5 was related to the storage substance metabolism, which regulated starch and protein accumulation under elevated temperature. Conclusion: Auxin synthesis and calcium signal associated with signal transduction, other stress responses, protein transport and modification, and reactive oxygen species-related proteins may be key proteins responsive to stimulus in response to elevated temperature. Alpha-amylase isozyme 3E and seed allergy protein RA5 may be the key proteins to regulate grain storage substance accumulation and further influence quality under elevated temperature. This study enriched the regulatory factors involved in the response to elevated temperature and provided a new idea for a better understanding of grain response to temperature. [ABSTRACT FROM AUTHOR]

Auxin plays an essential role in modulating leaf development. However, its role in leaf development in rice (Oryza sativa L.) remains largely unknown. In this study, we found that PINOID (OsPID) and two Sister-of-PIN1s, termed PIN-FORMED1c (OsPIN1c) and OsPIN1d, are necessary for rice leaf development. The ospin1c ospin1d null mutant lines presented severe defects in leaf morphogenesis, including drooping and semi-drooping blades, an abnormally thickened sheath and lamina joint, and fused leaves with absent ligules and auricles. Loss-of-function ospid mutants displayed generally similar leaf morphology but lacked leaf fusion. Interestingly, misshaped leaf genesis displayed a preference for being ipsilateral. In addition, OsPIN1c and OsPID were commonly localized in the initiating leaf primordia. Furthermore, accompanied by the more severe organ morphogenesis in the ospin1c ospin1d ospid triple mutant, RNA sequencing analysis revealed that many genes essential for leaf development have an altered expression level. Together, this study furthers our understanding of the role auxin transport plays during leaf development in monocot rice. [ABSTRACT FROM AUTHOR]

Despite growing interest in controlled-release N fertilizers (CRNFs) because of their potential for enhancing nitrogen use efficiency (NUE) and economic returns, their comprehensive impact on machine-transplanted rice remains to be understudied. To address this gap, here, we present a two-year field experiment that assessed the impact of CRNF using mechanical deep placement fertilization (DPF) on rice cultivation. The study involved three CRNF types (bulk blending fertilizer (BBF), polymer-coated urea (PCU), and sulfur-coated urea (SCU)) and two fertilization methods (DPF and broadcast application), with a high-yield split fertilization of urea as a control (CK). The results showed that DPF, especially with SCU, greatly enhanced soil NH4+-N concentrations, NUE, rice yield, and economic benefits compared to broadcast application. BBF consistently exhibited superior NUE and notable economic benefits, regardless of the application method used. Conversely, single-time application of PCU was less favorable for rice growth. In conclusion, for optimal economic benefits and NUE, DPF combined with single-time application of SCU is recommended. However, if deep application is not feasible and only broadcasting is possible in rice cultivation, BBF emerges as the ideal choice for both high NUE and significant economic returns. This research offers insights for improved nitrogen management in machine-transplanted rice, effectively optimizing yield, NUE, and profitability. [ABSTRACT FROM AUTHOR]

Poor grain-filling initiation in inferior spikelets severely impedes rice yield improvement, while photo-assimilates from source leaves can greatly stimulate the initiation of inferior grain-filling (sink). To investigate the underlying mechanism of source-sink interaction, a two-year field experiment was conducted in 2019 and 2020 using two large-panicle rice cultivars (CJ03 and W1844). The treatments included intact panicles and partial spikelet removal. These two cultivars showed no significant difference in the number of spikelets per panicle. However, after removing spikelet, W1844 showed higher promotion on 1000-grain weight and seed-setting rate than CJ03, particularly for inferior spikelets. The reason was that the better sink activity of W1844 led to a more effective initiation of inferior grain-filling compared to CJ03. The inferior grain weight of CJ03 and W1844 did not show a significant increase until 8 days poster anthesis (DPA), which follows a similar pattern to the accumulation of photo-assimilates in leaves. After removing spikelets, the source leaves of W1844 exhibited lower photosynthetic inhibition compared to CJ03, as well as stronger metabolism and transport of photo-assimilates. Although T6P levels remained constant in both cultivars under same conditions, the source leaves of W1844 showed notable downregulation of SnRK1 activity and upregulation of phytohormones (such as abscisic acid, cytokinins, and auxin) after removing spikelets. Hence, the high sink strength of inferior spikelets plays a role in triggering the enhancement of source strength in rice leaves, thereby fulfilling grain-filling initiation demands. [ABSTRACT FROM AUTHOR]

Key message: SMC5/6 complex subunit OsMMS21 is involved in cell cycle and hormone signaling and required for stem cell proliferation during shoot and root development in rice. The structural maintenance of chromosome (SMC)5/6 complex is required for nucleolar integrity and DNA metabolism. Moreover, METHYL METHANESULFONATE SENSITIVITY GENE 21 (MMS21), a SUMO E3 ligase that is part of the SMC5/6 complex, is essential for the root stem cell niche and cell cycle transition in Arabidopsis. However, its specific role in rice remains unclear. Here, OsSMC5 and OsSMC6 single heterozygous mutants were generated using CRISPR/Cas9 technology to elucidate the function of SMC5/6 subunits, including OsSMC5, OsSMC6, and OsMMS21, in cell proliferation in rice. ossmc5/ + and ossmc6/ + heterozygous single mutants did not yield homozygous mutants in their progeny, indicating that OsSMC5 and OsSMC6 both play necessary roles during embryo formation. Loss of OsMMS21 caused severe defects in both the shoot and roots in rice. Transcriptome analysis showed a significant decrease in the expression of genes involved in auxin signaling in the roots of osmms21 mutants. Moreover, the expression levels of the cycB2-1 and MCM genes, which are involved the cell cycle, were significantly lower in the shoots of the mutants, indicating that OsMMS21 was involved in both hormone signaling pathways and the cell cycle. Overall, these findings indicate that the SUMO E3 ligase OsMMS21 is required for both shoot and root stem cell niches, improving the understanding of the function of the SMC5/6 complex in rice. [ABSTRACT FROM AUTHOR]

Key message: The transcription elongation factor SPT4/SPT5 complex is essential for rice vegetative and reproductive growth and that OsSPT5-1, with its interactor APO2, is involved in multiple phytohormone pathways. The SPT4/SPT5 complex is a transcription elongation factor that regulates the processivity of transcription elongation. However, our understanding of the role of SPT4/SPT5 complex in developmental regulation remains limited. Here, we identified three SPT4/SPT5 genes (OsSPT4, OsSPT5-1, and OsSPT5-2) in rice, and investigated their roles in vegetative and reproductive growth. These genes are highly conserved with their orthologs in other species. OsSPT4 and OsSPT5-1 are widely expressed in various tissues. By contrast, OsSPT5-2 is expressed at a relatively low level, which could cause osspt5-2 null mutants have no phenotypes. Loss-of-function mutants of OsSPT4 and OsSPT5-1 could not be obtained; their heterozygotes showed severe reproductive growth defects. An incomplete mutant line (osspt5-1#12) displayed gibberellin-related dwarfed defects and a weak root system at an early vegetative phase, and a short life cycle in different planting environments. Furthermore, OsSPT5-1 interacts with the transcription factor ABERRANT PANICLE ORGANIZATION 2 (APO2) and plays a similar role in regulating the growth of rice shoots. RNA sequencing analysis verified that OsSPT5-1 is involved in multiple phytohormone pathways, including gibberellin, auxin, and cytokinin. Therefore, the SPT4/SPT5 complex is essential for both vegetative and reproductive growth in rice. [ABSTRACT FROM AUTHOR]

Seed dormancy and germination are regulated by endogenous gene expression as well as hormonal and environmental conditions, such as salinity, which greatly inhibits seed germination. MOTHER OF FT AND TFL1 (MFT), which encodes a phosphatidylethanolamine-binding protein, is a key regulator of seed germination in Arabidopsis thaliana. There are two orthologous genes of AtMFT in rice (Oryza sativa), namely, OsMFT1 and OsMFT2. However, the functions of these two genes in regulating rice seed germination under salt stress remain unknown. In this study, we found that seeds of loss-of-function osmft1 mutants germinated faster than wild-type (WT) seeds under salt stress, but this was not the case for loss-of-function osmft2 mutants. Overexpression of OsMFT1 (OsMFT1OE) or OsMFT2 increased the sensitivity to salt stress during seed germination. Transcriptome comparisons of osmft1 vs WT in the absence and presence of salt stress yielded several differentially expressed genes, which were associated with salt stress, plant hormone metabolism and signaling pathways, such as B-BOX ZINC FINGER 6 , O. sativa bZIP PROTEIN 8 and GIBBERELLIN (GA) 20-oxidase 1. In addition, the sensitivity of OsMFT1OE seeds to GA and osmft1 seeds to abscisic acid (ABA) during seed germination increased under salt stress. Overall, our results indicate that ABA and GA metabolism and their signaling pathways are regulated by OsMFT1 , modulating seed germination in rice under salt stress. [ABSTRACT FROM AUTHOR]

Stem mechanical strength is an important agricultural quantitative trait that is closely related to lodging resistance in rice, which is known to be reduced by fertilizer with higher levels of nitrogen. To understand the mechanism that regulates stem mechanical strength in response to nitrogen, we analysed stem morphology, anatomy, mechanical properties, cell wall components, and expression of cell wall-related genes, in two varieties of japonica rice, namely, Wuyunjing23 (lodging-resistant variety) and W3668 (lodging-susceptible variety). The results showed that higher nitrogen fertilizer increased the lodging index in both varieties due to a reduction in breaking strength and bending stress, and these changes were larger in W3668. Cellulose content decreased slightly under higher nitrogen fertilizer, whereas lignin content reduced remarkably. Histochemical staining revealed that high nitrogen application decreased lignin deposition in the secondary cell wall of the sclerenchyma cells and vascular bundle cells compared with the low nitrogen treatments, while it did not alter the pattern of cellulose deposition in these cells in both Wuyunjing23 and W3668. In addition, the expression of the genes involved in lignin biosynthesis, OsPAL, OsCoMT, Os4CL3, OsCCR, OsCAD2, OsCAD7, OsCesA4, and OsCesA7, were also down-regulated under higher nitrogen conditions at the early stage of culm growth. These results suggest that the genes involved in lignin biosynthesis are down-regulated by higher nitrogen fertilizer, which causes lignin deficiency in the secondary cell walls and the weakening of mechanical tissue structure. Subsequently, this results in these internodes with reduced mechanical strength and poor lodging resistance. [ABSTRACT FROM AUTHOR]

Ammonia (NH3) volatilization from paddy fields is a major issue which leads to poor fertilizer use efficiency and is considered a severe threat to the atmosphere. The previous research studies gave importance to the use of nitrogen fertilizers to mitigate NH3 volatilization, while very little emphasis was given to the role of other fertilizers, such as phosphorus (P), for the alleviation of NH3 volatilization in rice fields. Considering P importance herein, we conducted two consecutive field experiments using an innovative, controlled-release, phosphorus-blended fertilizer (CRPBF, with levels CRP0, CRP1, and CRP2). We compared CP0 (in which no fertilizer was applied), CP1 (112.5 kg P ha−1 P of locally recommended fertilizers), and CP2: (P and K blended fertilizers) to determine the best possible way to reduce NH3 volatilization without affecting the yield and quality of rice. The results of the study suggested that the yield of rice increased significantly with the application of CRP1 (11.11 t ha−1) and CRP2 (11.99 t ha−1). The addition of CRP1 and CRP2 to the rice field also enhanced yield-related components, i.e., panicle weight, total spikelets per unit area, spikelets per panicle, and above-ground biomass. CRP0 showed a lower yield and related components when compared to CP2. The addition of CRP1 and CRP2 demonstrated lower protein contents when compared to other treatments. The CRPBF application improved starch content and taste scores, and reduced the chalkiness of the rice grain during both years. The results showed a decreasing trend in NH3 volatilization from CRPBF amendments by improving the nitrogen use efficiency traits when compared to other treatments: CRP2, CRP1, and CRP0 reduced NH3 volatilization by 45%, 35%, and 15%, respectively. The results of this study indicate that, due to the episodic nature of NH3 volatilization, CRPBFs with 50% P and 100% P can markedly reduce NH3 volatilization from paddy fields without compromising the yield and quality of the crop, and could be a promising alternative to the ordinary commercial fertilizers used in rice fields. [ABSTRACT FROM AUTHOR]

A reduced basal and increased topdressing fertilizer rate (RBIT) can usually increase rice yield, but whether this practice alleviates the impact of poor weather on rice production is unknown. Thus, the effect of three integrated RBIT treatments (RBITs, including RBIT alone, RBIT in combination with straw incorporation (RBITS) or a reduced fertilizer rate (RBITR)) on rice growth and nutritional status under different weathers was investigated in a 9-year experiment. Conventional fertilization (CF) was the control. We found that daytime temperature and light (DTL) after heading were the main meteorological factors limiting rice yield increases. RBITs did not affect rice yield under High-DTL, compared with CF, but RBITS significantly increased rice yield under Low-DTL. Compared with High-DTL, the positive effect of RBIT and RBITR on the N concentration and proportion in vegetative organs under Low-DTL was higher than the K concentration in vegetative organs, but RBITS showed the opposite trend. Regression analysis indicated that the harvest index had stronger correlations with the N concentration (negative), K concentration (positive), and N/K (negative) in vegetative organs under Low-DTL than under High-DTL. Our findings suggested that RBITS could improve rice adaptability to daytime temperature and light changes after heading by balancing crop nutritional status (N/K). [ABSTRACT FROM AUTHOR]

Glucose-6-phosphate dehydrogenase (G6PDH) catalyzes a metabolic hub between glycolysis and the pentose phosphate pathway (PPP), which is the oxidation of glucose-6-phosphate (G6P) to 6-phosphogluconolactone concomitantly with the production of nicotinamide adenine dinucleotide phosphate (NADPH), a reducing power. It is considered to be the rate-limiting step that governs carbon flow through the oxidative pentose phosphate pathway (OPPP). The OPPP is the main supplier of reductant (NADPH) for several "reducing" biosynthetic reactions. Although it is involved in multiple physiological processes, current knowledge on its exact role and regulation is still piecemeal. The present review provides a concise and comprehensive picture of the diversity of plant G6PDHs and their role in seed germination, nitrogen assimilation, plant branching, and plant response to abiotic stress. This work will help define future research directions to improve our knowledge of G6PDHs in plant physiology and to integrate this hidden player in plant performance. [ABSTRACT FROM AUTHOR]

Not enough attention has been paid to the comparison in yield performance and N responsiveness between hybrid rice and inbred rice using the large number of new cultivars released after 2000 under machine transplanting. Field experiments were conducted in 2017 and 2018; 48 widely planted rice cultivars included four groups, namely indica hybrids (IHs), japonica inbreds (JIs), indica-japonica hybrids (IJHs), and indica inbreds (IIs) that were transplanted by machine with three nitrogen fertilizer levels (0, 150, 300 kg ha−1). The average yield of the hybrids (IHs, IJHs) was higher than that of JIs or IIs with a higher crop-growing rate (CGR) during the total growth duration, regardless of the N application level; moreover, longer total growth duration was responsible for the higher yield in IJHs than in IHs. The IHs had a large gap yield which mainly came from the genetic improvement in the CGR during the grain-filling stage. The yield gap was relatively small in JIs, and longer growth duration combined with optimal daily mean temperature during the grain-filling stage was the critical factor for high yield. The JIs or IJHs had higher yield under the N300 level, while the response of IHs to nitrogen varied with different cultivars. Cultivars with higher CGR during the grain-filling stage had higher yield under the N300 level. In conclusion, this study suggests that high CGR during the grain-filling stage may be a vital trait for the development of rice with high yield and high N responsiveness at machine transplanting. [ABSTRACT FROM AUTHOR]

Sucrose non-fermenting-1-related protein kinase 1 (SnRK1) plays a key role in rice germination. The small molecule drug, A-769662, activates AMP-activated protein kinase, a mammalian homolog of SnRK1. However, it is unknown whether A-769662 activates SnRK1, thereby affecting germination. SnRK1 in desalted extracts from germinating rice seeds was strongly activated by adding A-769662 in vitro. Applying 50 or 100 μM A-769662 accelerated germination and increased the root length, shoot length, and seedling fresh weight. 50 μM A-769662 treatment increased the catalytic activity and phosphorylation of SnRK1 during germination. Transcriptome analysis and biochemical validation were performed to investigate the mechanism whereby A-769662 treatment promoted rice germination. A-769662 treatment promoted starch hydrolysis by increasing the expression and activity of amylase and inhibited starch biosynthesis by decreasing the expression of OsAGPL2 , OsAGPS2a , Wx , and SSIIa. The abscisic acid (ABA) level and gene expression of ABA-induced transcription factors, including OsNF-YC9 , OsNF-YC12 , OsWRKY24 , OsPYL8 , OsMKKK62 , and OsMKKK63 , which reduced the inhibition of germination by ABA were decreased under 50 μM A-769662 treatment. The increased expression of the OsACO3 and OsACO5 genes and increased ethylene levels under A-769662 treatment, which counteracted the inhibition of ABA on germination and, thus, promoted germination. These results demonstrate the activation of A-769662 on SnRK1 and further reveal the regulatory mechanism of A-769662 in rice seed germination and nutrient remobilization. • AMPK activator, A-769662, strongly increases SnRK1 activity in vitro. • A-769662 treatment accelerates germination by affecting amylase gene expression, ABA pathway and ethylene biosynthesis. • SnRK1 may alter T6P level by regulating expression of TPP genes. [ABSTRACT FROM AUTHOR]

Rice paddies supply the staple food for 50% global population, but contribute 48% of greenhouse gas (GHG) emissions from croplands. Temperature is the key factor of rice yield and GHG emissions, but warming effects (i.e. elevated temperature ≤ 2°C) are still unclear, especially in hotspots. Therefore, we collected the global in-situ observations of warming experiments and corresponding environmental factors to identify the key drivers of warming effects, and developed the statistic models to assess the effects of warming on GHG emissions from China's rice paddies. Our results indicate that the variation in warming effects on rice yield, methane (CH 4) emissions, and nitrous oxide (N 2 O) emissions are primarily explained by ambient temperature of post-anthesis, ambient temperature of flooding stage, and soil pH, respectively. Considering these key factors, we estimate that warming does not significantly affect China's total rice yield, while can increase CH 4 emissions by 13.6% °C−1, N 2 O emissions by 30.5% °C−1, and area-/yield-scaled GHG emissions by 14.9% °C−1 from China's rice paddies. Warming reduces rice yield but increases GHG emissions more strongly in East, South and Central China, compared to North, Northwest, Northeast, and Southwest China. Our findings quantify the warming effects on rice yield and GHG emissions, and provide new perspectives for the hotpots of warming effects on China's rice production. In the warmer future, we still need more efforts on smart adaptation strategies to maintain rice yield and curb GHG emissions from rice agriculture. • Temperature and soil pH can explain variation in warming effect on GHG emissions. • Warming effect on N 2 O emissions shows a negative relationship with soil pH. • Warming does not affect China's total rice yield while increases GHG emissions. • Warming increases yield-scaled GHG emissions by 14.9% °C−1 in China's paddies. • East, South and Central China's rice paddies are the hotspots of warming effects. [ABSTRACT FROM AUTHOR]

Monitoring crops with high spatio-temporal resolution satellites provides valuable observations to ensure food security in the global change context. This study focuses on estimating the Green Area Index (GAI) to monitor wheat crops with a spatial resolution of 3 m and daily satellite observations from the SuperDove constellation. With an easier access to large training datasets of ground GAI measurements, and the improvement of the realism of radiative transfer model simulations, the choice of the optimal approach (data-driven or model-driven) constitutes a key question when retrieving GAI from satellite observations. This study compares a data-driven and a model-driven approach to estimate GAI from the SuperDove satellites. Both approaches are based on Gaussian Process Regression (GPR) machine learning techniques. The data-driven approach uses over 300 ground GAI measurements collected from 12 sites in China and France, each with 20 to 51 contrasting plots. The model-driven approach uses 10,000 simulations of top of canopy reflectance and the corresponding GAI values generated by the LESS radiative transfer model applied to 3D scenes built with the ADEL-Wheat (Architectural model of Development based on L-systems) model. Results confirm that the SuperDove reflectance are reliable and consistent with Sentinel-2 values. When estimating GAI using GPR with SuperDove top of canopy reflectance, the model-driven approach (R2 = 0.83, RMSE = 0.80, Accuracy = 0.01 and Precision = 0.80) generally outperforms the data-driven approach (R2 = 0.80, RMSE = 0.88, Accuracy = −0.13 and Precision = 0.87), except for small GAI values. In-silico experiments show that the uncertainties in the ground-measured GAI and the size and diversity of the training datasets limit the data-driven approach. In contrast, the model-driven approach is mostly constrained by the realism of the reflectance simulations, particularly for low GAI values. Two ensemble solutions based on the weighted average of the two previous approaches are then proposed: the global ensemble solution (R2 = 0.86, RMSE = 0.75, A = −0.06 and P = 0.74) where the weight is assumed independent from the GAI values, and the adaptive ensemble solution (R2 = 0.85, RMSE = 0.76, A = −0.08 and P = 0.76) where the weight depends on the GAI values. Both solutions perform similarly, improving both data-driven and model-driven approaches. Finally, applying both solutions to monitor wheat plots along the growth cycle allows clear differentiation of nitrogen modalities and cultivar effects. However, a minimum plot size of 12 m × 12 m (4 × 4 pixels) is recommended to minimize the co-registration errors and increase estimate precision. • Data-driven and model-driven approaches for GAI retrieval of wheat from PlanetScope. • The model-driven approach outperforms the data-driven one except for low GAI values. • Both approaches were combined in an ensemble solution which improves GAI estimates. • The proposed methodology allows accurate and precise monitoring of wheat crops. [ABSTRACT FROM AUTHOR]

With the intensification of global warming, high temperatures during rice's growth and development could further lead to a deterioration in rice yields. Therefore, it is particularly important to further clarify the response of the rice booting stage to high temperatures, and to explore reasonable countermeasures on this basis to reduce yield losses. Methyl jasmonate (MeJA) is a derivative of jasmonates and is widely used for stress resistance. However, the role of MeJA in alleviating high temperatures during the rice booting stage has not been given enough attention. This study aimed to further evaluate the alleviation effect of methyl jasmonate on high-temperature stress during the key growth period of local conventional japonica rice. The results showed that high temperatures (37.5 °C/27.0 °C) at the booting stage had a significant impact on the antioxidant system of rice and also significantly reduced the photosynthetic capacity of the plant, resulting in a decrease in the final yields. The exogenous spraying of 0.1 mmol/L MeJA at the booting stage could effectively alleviate the influence of high-temperature stress on rice photosynthesis. Exogenous MeJA increased the stomatal conductance (Gs) of rice leaves under high-temperature stress, and correspondingly increased the transpiration rate (Tr) and decreased the organ temperature of rice plants, thereby reducing the damage to the actual photochemical efficiency (ΦPSII) caused by high temperatures. By increasing the carotenoid content (Car) and reducing the malondialdehyde content (MDA), the antioxidant capacity of the plants was restored to a certain extent under exogenous MeJA, and the yield factor showed an increase in the number of grains per panicle and the seed-setting rate of Wuyunjing 24, which alleviated the booting stage yield losses induced by high-temperature stress. In conclusion, the application of exogenous MeJA at the booting stage alleviated the negative consequences of high temperatures by enhancing the plants' antioxidant and photosynthetic capacity. Therefore, MeJA may have a potential role in mitigating the challenges of global warming in rice production. [ABSTRACT FROM AUTHOR]

Cytokinins play key roles in plant growth and development, and hence their biosynthesis and degradation have been extensively studied. Cytokinin oxidase/dehydrogenases (CKXs) are a group of enzymes that regulate oxidative cleavage to maintain cytokinin homeostasis. In rice, 11 CKX genes have been identified to date; however, most of their functions remain unknown. In this study, we comprehensively examined the expression patterns and functions of the CKX s in rice by using CRISPR/Cas9 technology to construct mutants of all 11 genes. The results revealed that the ckx single-mutants and higher-order ckx4 ckx9 mutant lines showed functional overlaps and sub-functionalization. Notably, the ckx1 ckx2 and ckx4 ckx9 double-mutants displayed contrasting phenotypic changes in tiller number and panicle size compared to the wild-type. In addition, we identified several genes with significantly altered expression in both the ckx4 and ckx9 single-mutant and double-mutant plants. Many of the differentially expressed genes were found to be associated with auxin and cytokinin pathways, and cytokinins in the ckx4 ckx9 double-mutant were increased compared to the wild-type. Taken together, our findings provide new insights into the functions of CKX genes in rice growth and may provide the foundations for future studies aimed at improving rice yield. [ABSTRACT FROM AUTHOR]

Key message: Chromatin remodeling ATPases OsSYD and OsBRM are involved in shoot establishment, and both affect OSH gene transcription. OsSYD protein interacts with RFL, but OsBRM does not. In plants, SPLAYED (SYD) and BRAHMA (BRM) encode chromatin remodeling ATPases that use the energy derived from ATP hydrolysis to restructure nucleosomes and render certain genomic regions available to transcription factors. However, the function of SYD and BRM on rice growth and development is unknown. Here, we constructed ossyd and osbrm mutants using CRISPR/Cas9 technology and analyzed the effects of mutations on rice embryo development. We discovered that the ossyd and osbrm mutants exhibited severe defects during embryonic development, whereas endosperm development was normal. These results indicated that the development of the embryo and endosperm is independent of each other. Consequently, the ossyd- and osbrm-null mutants did not germinate due to the abnormal embryos. Furthermore, we observed the embryos of ossyd- and osbrm-null mutants, and they indeed had distinct differentiation defects in shoot establishment, acquired during embryogenesis. To verify the function of OsSYD and OsBRM in embryogenesis, we measured the transcript levels of marker genes at different stages. Compared with wild type, the expression levels of multiple OSH genes were significantly reduced in the mutants, which was consistent with the defective shoot establishment phenotypes. The interaction between SYD and RICE FLORICAULA/LFY (RFL) was revealed using a yeast two-hybrid screening system, suggesting that the interaction between the LFY homolog and chromatin remodeling ATPases is ubiquitous in plants. Collectively, our findings provide the basis for elucidating the function of OsSYD and OsBRM during embryo development in rice. [ABSTRACT FROM AUTHOR]

Grains located on different positions of the panicle differed in grain weight and quality performance, however, the comprehensive effect of sowing dates on physiological and quantitative characteristics of grains located on different positions still remains unclear. In this study, a field experiment was conducted with two japonica rice cultivars, Nanjing 9108 and Ningjing 7, under 3 sowing dates (S1, 30th April; S2, 30th May; S3, 30th June). Delayed sowing treatments increased before-heading mean temperature (Tmean), day temperature (Tday), night temperature (Tnight) and mean solar radiation (Smean) for 0.94 °C, 0.99 °C, 1.23 °C, and 1.04 MJ, respectively, while decreased growth duration (GD) for 13.4 days, with 30 days delaying sowing date. Elevated before heading thermal resources and shortened GD contributed to enlarged panicle size via enhancing number of grains on secondary branches (SG) and led to higher ratio of SG per unit area (SG%). Meanwhile, delayed sowing decreased after heading Tmean, Tday, Tnight and Smean by 0.84 °C, 1.23 °C, 1.13 °C, and 2.12 MJ, respectively, with 30 days delaying sowing, and further enhanced rice stickiness (ST), peak viscosity (PKV) and breakdown (BD), but suppressed hardness (HD), amylose content (AC), cold pasting viscosity (CPV), hot pasting viscosity (HPV) and setback (SB) of SG, whilst grains on primary branches (PG) di no significant differences. Elevated taste and cooking quality of SG under delayed sowing was regulated by slower grain filling rate, which is largely regulated by AGPase and GBSS. Compared to PG, SG has better physiochemical, texture properties and RVA profiles due to its slower starch biosynthesis. The above results suggested that physiological (starch biosynthesis of SG) and quantitative parameters (amount of SG) of the rice population should be referred simultaneously to improve rice cooking and taste quality. [ABSTRACT FROM AUTHOR]

The remobilization of non-structural carbohydrates (NSCs) in the stem is essential for rice grain filling so as to improve grain yield. We conducted a two-year field experiment to deeply investigate their relationship. Two large-panicle rice varieties with similar spikelet size, CJ03 and W1844, were used to conduct two treatments (removing-spikelet group and control group). Compared to CJ03, W1844 had higher 1000-grain weight, especially for the grain growth of inferior spikelets (IS) after removing the spikelet. These results were mainly ascribed to the stronger sink strength of W1844 than that of CJ03 contrasting in the same group. The remobilization efficiency of NSC in the stem decreased significantly after removing the spikelet for both CJ03 and W1844, and the level of sugar signaling in the T6P-SnRK1 pathway was also significantly changed. However, W1844 outperformed CJ03 in terms of the efficiency of carbon reserve remobilization under the same treatments. More precisely, there was a significant difference during the early grain-filling stage in terms of the conversion of sucrose and starch. Interestingly, the sugar signaling of the T6P and SnRK1 pathways also represented an obvious change. Hence, sugar signaling may be promoted by sink strength to remobilize the NSCs of the rice stem during grain filling to further advance crop yield. [ABSTRACT FROM AUTHOR]

Nitrogen (N) plays a vital role in plant growth; however, the yield response to N fertilizer is regularly declining in the major cropping systems due to overuse and the upper limit of yields. Heavy losses of N are also documented due to its excessive use in the rice-wheat rotation system, resulting in low nitrogen-use efficiencies (NUE) and environmental problems. Therefore, a three-year field experiment was performed with different N managements to investigate the impact of reduced N input rates in this exhaustive cropping system. Reducing the N application rates did not affect the wheat and rice yields significantly, only during the second wheat season was the yield slightly reduced as compared to higher N input treatments. Decreasing the N input rates in the prior crop and present crop, and the interactions of both rice and wheat seasons (R × W) did not influence the yields of either crop. A reduction in N fertilizer had a considerable impact on dry matter production during the wheat seasons but demonstrated no effect during the rice season. The accumulation of N was significantly reduced during both crop seasons by lowering the rate of N application. In addition, the NUE indices were significantly influenced by N fertilizer application rates. In conclusion, N fertilizer input rates for both rice and wheat crops can be lowered as compared to present fertilization rates without any risk of yield decline. Lowering the N input increases the NUE and effectively reduces N losses, and soil N status can also be maintained. [ABSTRACT FROM AUTHOR]

The essential role of auxin in plant growth and development is well known. Pathways related to auxin synthesis, transport and signaling have been extensively studied in recent years, and the PIN-FORMED (PIN) protein family has been identified as being pivotal for polar auxin transport and distribution. However, research focused on the functional characterization of PIN proteins in rice is still lacking. In this study, we investigated the expression and function of OsPIN1c and OsPIN1d in the japonica rice variety (Nipponbare) using gene knockout and high-throughput RNA sequencing analysis. The results showed that OsPIN1c and OsPIN1d were mainly expressed in young panicles and exhibited a redundant function. Furthermore, OsPIN1c or OsPIN1d loss-of-function mutants presented a mild phenotype compared with the wild type. However, in addition to significantly decreased plant height and tiller number, panicle development was severely disrupted in double-mutant lines of OsPIN1c and OsPIN1d. Severe defects included smaller inflorescence meristem and panicle sizes, fewer primary branches, elongated bract leaves, non-degraded hair and no spikelet growth. Interestingly, ospin1cd-3 , a double-mutant line with functional retention of OsPIN1d, showed milder defects than those observed in other mutants. Additionally, several critical regulators of reproductive development, such as OsPID, LAX1, OsMADS1 and OsSPL14 / IPA1 , were differentially expressed in ospin1c-1 ospin1d-1 , supporting the hypothesis that OsPIN1c and OsPIN1d are involved in regulating panicle development. Therefore, this study provides novel insights into the auxin pathways that regulate plant reproductive development in monocots. [ABSTRACT FROM AUTHOR]

Rice paddies contribute to ∼48% of greenhouse gas emissions from cropland, with ∼94% from methane (CH 4). Elevated atmospheric CO 2 concentrations (eCO 2) due to human activities, generally stimulate the rice growth, and in turn affect CH 4 emissions from rice paddies. However, the effects of eCO 2 on CH 4 emissions from rice paddies are still unclear under in situ straw incorporation, the popular agricultural practice. Therefore, we conducted a 3-yr field experiment to investigate the effects of eCO 2 on CH 4 emissions under in situ straw incorporation in the rice-wheat cropping system, using the open-top chamber technology. We found that eCO 2 reduced the CH 4 emissions from rice paddies by 10.9–23.8%, but increased rice plant biomass by 4.2–35.6%. The eCO 2 reduced the soil NH 4 + and NO 3 - concentrations, but did not affect the soil dissolved organic C. The eCO 2 did not affect the abundance of methanogens and CH 4 production potential, whereas it stimulated the abundance of methanotrophs and CH 4 oxidation potential by 102.5% and 15.1%, respectively. The eCO 2 also shifted the community composition of methanotrophs and reduced the relative abundance of type Ⅱ methanotrophs by 8.5%. The random forest analysis identified that soil CH 4 oxidation potential is the most important factor affecting CH 4 emissions. Our findings indicate that eCO 2 can reduce the CH 4 emissions from rice paddies under in situ straw incorporation mainly through increasing the soil CH 4 oxidation potential. Our study suggests the effects of eCO 2 on CH 4 emissions from global paddies may be overestimated and underline the need for smart agricultural management to reduce CH 4 emissions. • Elevated CO 2 reduced CH 4 emission from paddies under in situ straw incorporation. • Elevated CO 2 stimulated abundance of methanotrophs and CH 4 oxidation potential. • Soil CH 4 oxidation potential is the most important factor affecting CH 4 emissions. [ABSTRACT FROM AUTHOR]

Climate change threatens rice production by increasing the frequency of extreme temperatures during grain-filling stage (T GF). Nitrogen application can significantly affect rice yield and quality. However, the effects of interaction between T GF and nitrogen application rate on yield and quality of rice remains unclear. The objectives of this study were to comprehensively evaluate the quantitative regulatory mechanism between T GF and nitrogen application rate on rice yield and quality formation. A two-year field experiment with three varieties, five sowing dates, and three nitrogen application rates was conducted at four ecological sites in the middle and lower reaches of the Yangtze River, China in 2019 and 2020. Grain yield, milling, appearance, and eating quality were quantified for each treatment. This study demonstrated that T GF varied from 17.8 ℃ to 31.4 ℃ in different sites and sowing dates and decreased by an average of 2.1 ℃ for every 15 days the sowing date was delayed. The grain yield, head rice rate, chalky grain rate, chalkiness and taste value were all related to T GF through a quadratic function. The optimum T GF for both yield and quality of indica hybrid rice was 24.2–26.5 ℃. In terms of grain yield, nitrogen agronomic efficiency increased linearly with T GF , and nitrogen application could only confer a small increase in yield or even reduce yield under extreme low T GF. Nitrogen application alleviated the adverse effects of high T GF on rice quality, but exacerbated the deterioration of quality under low T GF. For milling and appearance quality and eating quality, the critical T GF leading to such opposite regulatory effect were identified as 23.4 ± 0.4 ℃ and 29.5 ± 0.5 ℃, respectively. The variations of the ratio of amylopectin to amylose and protein content altered texture and starch gelatinization properties, mainly explaining the differences in eating quality caused by T GF and nitrogen application rate. The present study suggests that T GF should be considered when formulating nitrogen management strategies for high-quality rice, which is crucial for alleviating the deterioration of rice quality caused by extreme T GF under global climate change. [Display omitted] • The optimum temperature during grain filling stage (T GF) for indica hybrid rice was 24.2–26.5 ℃. • Nitrogen agronomic efficiency was significantly positively correlated with T GF. • Nitrogen application could alleviate the adverse effects of high T GF on rice quality. • Nitrogen application exacerbated the deterioration of quality under low T GF. [ABSTRACT FROM AUTHOR]

Straw incorporation has been widely recommended as an effective management practice to increase soil nitrogen stocks in agroecosystems worldwide. However, the overall trend and magnitude of changes in various soil organic nitrogen fractions in response to crop residue return and their contribution to soil nitrogen sequestration remain uncertain. Here, we show through a long-term experiment (12 years) that straw return increased soil total nitrogen and soil nitrogen sequestration rate by 20.01% and 120.95%, respectively. Ammonia nitrogen, amino acid nitrogen, and amino sugar nitrogen were affected by straw and its interaction with year, and increased by 43.08%, 27.70%, and 46.56%, respectively, with the highest growth rate in amino acid nitrogen (10.51 mg kg−1 yr−1). Furthermore, redundancy analyses showed that soil total organic carbon and C:N ratio were the major factors explaining the variations in soil organic nitrogen fractions, which increased by 46.22% and 21.75%, respectively. The structural equation model further revealed that amino acid nitrogen was a pivotal driver of soil nitrogen sequestration, because the soil C:N ratio indirectly influenced soil nitrogen sequestration via affecting the accumulation of amino acid nitrogen. Our results suggest that long-term straw return can improve nitrogen sequestration by accelerating the accumulation of amino acid nitrogen and that soil nitrogen storage and supply capacity may be improved by adopting straw incorporation and other appropriate management practices to regulate soil stoichiometry. • Straw return promoted soil nitrogen sequestration. • Straw return increased soil organic nitrogen fractions. • Straw return increased the soil TOC and C:N ratio. • TOC and C:N ratio explained the variations of soil organic nitrogen fractions. • Amino acid nitrogen was a pivotal driver of soil nitrogen sequestration. [ABSTRACT FROM AUTHOR]

Accurately simulating paddy water nitrogen and phosphorus (N/P) concentration is crucial for identifying key control areas of agricultural non-point source pollution (ANPSP), especially in the paddy-dominated regions. In China, smallholder farming has resulted in significant spatiotemporal heterogeneity in fertilizer application date/amount among different fields at the regional scale. However, due to the lack of realistic fertilizer application date/amount data at field scale, previous regional scale models have employed uniform fertilization management, neglecting spatiotemporal heterogeneity in fertilizer application date/amount. This has led to significant uncertainties in assessing paddy water N/P pollution at the regional scale. To address this issue, we developed a new model (PWNPRS) for simulating spatiotemporal hotspots of paddy water N/P pollution, based on remote sensing and a first-order kinetic model: (1) we developed a quantitative assessment method for fertilizer application date/amount based on phenological/vegetation information extracted from remote sensing datasets; (2) we modified and improved the first-order kinetic model by incorporating fertilizer application date/amount to predict paddy water N/P concentration at the regional scale. The spatiotemporal fluctuations of fertilizer application date/amount and paddy water N/P pollution were simulated by using the developed model in a paddy-dominated regions in Danyang, China, as a case study for model validation. The models performances and spatiotemporal evaluation indicate that the PWNPRS model is an innovative and promising approach to accurately capture the spatiotemporal pattern of fertilizer application date/amount and paddy water N/P concentration at the regional scale. The PWNPRS model can be extended to other paddy-dominated regions for N/P concentration prediction under data-limited conditions. Our model considers the interactive effects of fertilization date/amount and N/P concentration attenuation rates, allowing it to capture the dynamic spatiotemporal variations in paddy water N/P concentrations at a regional scale. Simultaneously, a robust and accurate model provide a theoretical basis for optimizing agricultural ecological management. [Display omitted] • Developed remote sensing-based model to simulate paddy water N/P pollution. • Incorporated spatiotemporal fertilizer application patterns into pollution model. • Validated model performance in paddy region showing improved prediction. • Captured heterogeneity in smallholder fertilizer use impacting water quality. • Provides targeted management of agricultural pollution in data-scarce regions. [ABSTRACT FROM AUTHOR]

The majority of investigations on mechanisms underlying yield difference between superior and conventional cultivars has focused on the grain-filling stage after anthesis. However, the physiological process before anthesis has been less explored. We aimed to quantify the contribution of canopy photosynthesis at pre-anthesis stage to grain yield formation and clarify the mechanism underlying the yield advantage of the superior cultivars. This study selected representative cultivars of indica and japonica rice, each type having a pair of cultivars with ideal plant architecture (IPA) and conventional architecture. Field experiments over four years (2019–2022) were conducted to compare the relevance of canopy photosynthesis to yield formation between the phases before and after anthesis. The two IPA cultivars, JYZK-6 and ZZY-1, produced higher grain yield than the two conventional cultivars, NJ-5055 and HHZ. JYZK-6 and ZZY-1 also had good distribution of light interception inside the canopy, with the middle and lower part receiving more light than NJ-5055 and HHZ. At leaf level, there was no significant difference in photosynthetic rate between the two types of cultivars. At canopy level, the IPA cultivars had stronger photosynthetic activities before anthesis, outperforming NJ-5055 by 35.56% in averaged canopy photosynthesis, and by 46.65% in averaged daily net photosynthetic accumulation in 2021–2022. By contrast, canopy photosynthesis after anthesis was not significantly different between the two types. The IPA cultivars stored heavier biomass in internodes and sheaths before anthesis and remobilized more reserves to the developing grains, with the remobilization rate being 16.42% (internodes) and 35.34% (sheaths) higher than NJ-5055 and HHZ. The higher canopy productivity before anthesis is one of the main reasons accounting for the superior IPA cultivars, suggesting the necessity of optimizing plant growth and development during the vegetative and reproductive phases. • Canopy photosynthesis was compared between IPA and conventional cultivars. • IPA cultivars had a good distribution of light interception inside the canopy. • IPA cultivars had stronger canopy photosynthetic activities before anthesis. • We suggest the necessity of optimizing canopy structure development before anthesis. [ABSTRACT FROM AUTHOR]

• Elevated temperatures affect structural parameters of starch chain length distribution. • Nitrogen decreased the height of fifth amylopectin peak that increased at elevated temperature. • Nitrogen increased the height of second amylose peak at elevated temperature. • Nitrogen changed pasting properties and decreased relative crystallinity under warming. Nitrogen fertilization can mitigate the negative effects of high temperatures on rice. In this study, we simulated dynamic field temperature increases using a free-air temperature enhancement system. Changes in the physicochemical properties of starch were investigated under increasing nitrogen fertilization during the grain-filling stage. We observed that the application of nitrogen at elevated temperatures (ETN) did not change the chain length distribution compared with elevated temperatures (ET) alone; however, it did significantly increase the heights of the first and second amylose peaks. Specifically, ETN significantly decreased the height of fifth amylopectin and relative crystallinity, and the changes it introduced in the physicochemical properties of starch were greater than those of ET. Overall, these changes in starch properties may be associated with the ability of nitrogen to facilitate the maintenance of rice quality at high temperatures. [ABSTRACT FROM AUTHOR]

Abstract: The peripheral arterial chemoreflex, arising primarily from the carotid body in most species, plays an important role in the control of breathing and in autonomic control of cardiovascular function. The peripheral chemoreflex is enhanced in heart failure patients and animal models of heart failure and contributes to the sympathetic hyperactivity and breathing instability that exacerbates the progression of the disease. Studies in animal models have shown that carotid body chemoreceptor activity is enhanced under both normoxic and hypoxic conditions in heart failure due to disruption of local mediators that control carotid body function. This brief review highlights evidence that the alterations in the gasotransmitters, nitric oxide, carbon monoxide, and hydrogen sulfide in the carotid body contribute to the exaggerated carotid body function observed in heart failure. [Copyright &y& Elsevier]

Melatonin (MT), an important antioxidant existing in plants and animals, has been widely reported to participate in the process of plants coping with stress. In this study, we demonstrated the mechanism of MT enhancing photosynthesis in rice under salt stress. The results showed that MT treatment increased relative water content, sucrose and starch content of rice under salt stress. This was mainly owing to the fact that MT enhanced the net photosynthetic rate and enhanced the absorption and transmission of light energy. The effect of MT on photosynthesis of rice under salt stress conditions was mainly due to the regulation of three processes: maintaining low ROS status by improving the total antioxidant capacity, promoting the xanthophyll cycle and increasing the xanthophyll pool size to dissipate excess light energy, increasing the activities of key photosynthetic enzymes. Taken together, these results provide a mechanism for MT to improve the photosynthetic capacity of rice under salt stress. • MT improved plant growth and photosynthetic products accumulation under salt stress. • MT increased the net photosynthetic rate and electron transport of rice under salt stress. • MT increased the xanthophyll cycle and activities of key photosynthetic enzymes, decreased the accumulation of ROS. [ABSTRACT FROM AUTHOR]

Phloem loading is the first step in sucrose transport from source leaves to sink organs. The phloem loading strategy in rice remains unclear. To determine the potential phloem loading mechanism in rice, yeast invertase (INV) was overexpressed by a 35S promoter specifically in the cell wall to block sugar transmembrane loading in rice. The transgenic lines exhibited obvious phloem loading suppression characteristics accompanied by the accumulation of sucrose and starch, restricted vegetative growth and decreased grain yields. The decreased sucrose exudation rate with p-chloromercuribenzenesulfonic acid (PCMBS) treatment also indicated that rice actively transported sucrose into the phloem. OsSUT1 (SUCROSE TRANSPORTER 1) showed the highest mRNA levels of the plasma membrane-localized OsSUT s in source leaves. Cross sections of the OsSUT::GUS transgenic plants showed that the expression of OsSUT1 and OsSUT5 occurred in the phloem companion cells. Rice ossut1 mutants showed reduced growth and grain yield, supporting the hypothesis of OsSUT1 acting in phloem loading. Based on these results, we conclude that apoplastic phloem loading plays a major role in the export of sugar from rice leaves. [ABSTRACT FROM AUTHOR]

• Exogenous melatonin improves salt tolerance in rice seedlings. • Melatonin increases Na+ efflux and K+ influx in rice roots under salt stress. • Melatonin enhances the Na+/K+ homeostasis in rice under salt stress by increasing ATP content and H+-pump activity. • Melatonin increasing the root Na+/K+ transporters sensitivity to ROS/RNS. Salinity stress is one of the most serious factors limiting the productivity of crops. Rice at the seedling stage is extremely sensitive to salt. Studies have shown that melatonin can improve plant resistance to a variety of abiotic stresses, including salt stress. In this study, the mechanism of melatonin in regulating Na+/K+ homeostasis in rice seedlings was explored. The results showed that melatonin pretreatment increased rice dry weight and salt tolerance indices under salt stress. This is because melatonin inhibited the increase of Na+ content and the decrease of K+ content induced by salt stress and increased the ratio of K+/Na+. Melatonin increased the selective absorption indices of rice under salt stress, which indicated that melatonin pretreatment improved the ability of rice to absorb K+ and exclude Na+. The results of root Na+/K+ flux also confirmed this point. Rice pretreated with melatonin showed stronger roots Na+ efflux and K+ influx after salt stress. As signaling molecules, the content of nitric oxide increased in the roots of rice pretreated with melatonin, but the content of hydrogen peroxide decreased. Rice roots Na+/K+ transporters pretreated with melatonin were more sensitive to nitric oxide and hydrogen peroxide, which manifested as the Na+ efflux and K+ influx were stronger after being shocked by nitric oxide and hydrogen peroxide. This was due to melatonin pretreatment increasing roots' ATP content and H+-pump activity. These results indicated that exogenous melatonin could improve root Na+/K+ transporters' response to reactive oxygen species/reactive nitrogen species as well as increase ATP content and H+-pump activity to maintain Na+/K+ homeostasis in rice under salt stress. [ABSTRACT FROM AUTHOR]

SUMMARY: The CUP‐SHAPED COTYLEDON (CUC) genes (CUC1, CUC2 and CUC3) regulate organ boundary formation in Arabidopsis. However, the functions of their homologous genes in rice (Oryza sativa) are still unknown. Here, we have identified an orthologous gene of CUC1 and CUC2 in rice, named OsNAM. Subcellular localization and yeast two‐hybrid assay results have suggested that OsNAM encodes a conserved nuclear NAC (NAM/ATAF1/CUC2) protein with a transcriptional activator. The null mutant osnam‐1 presented a fused leaf structure, small panicles, reduced branches and aberrant floral organ identities when compared with those of the wild type. Beta‐glucuronidase staining and GFP reporter lines indicated that OsNAM was expressed in young tissues and that its boundary enrichment expression was regulated by OsmiR164. Loss‐of‐function mutants for OsCUC3 resulted in no obvious defects throughout rice development. The osnam oscuc3 double mutant, however, resulted in severe leaf fusion of the first two leaves, while the osnam single mutant showed a similar phenotype from the seventh leaf. These results indicated that OsNAM and OsCUC3 act redundantly for boundary specification during post‐embryonic development. Overall, we describe the biological functions of OsNAM and OsCUC3 in rice development and the expression characteristics of OsNAM. This work reveals the important role of CUC genes in rice. [ABSTRACT FROM AUTHOR]

The responses of rice quality including milling, appearance, and eating quality between superior (SG) and inferior grains (IG) to temperature during grain filling stage (T GF) remained poorly understood, especially for eating quality. Therefore, the regulation of T GF (17.6−30.4 °C) on quality of three indica hybrid varieties (IHs) was investigated by setting multiple sowing dates and the mechanism underlying taste difference was explored by monitoring chemical compositions, rapid visco analyser (RVA) profiles, and texture properties. Results suggested that T GF ranging from 23.3 to 25.2 °C could comprehensively improve the milling, appearance and eating quality of IHs, and the optimal T GF of SG was 2.3–4.2 °C lower than that of IG. Compared with chemical compositions and RVA profiles, texture properties were better for evaluating the eating quality of IHs. When T GF was higher than 24.0 °C, the taste value of IG was higher than that of SG mainly due to higher elasticity. The findings indicate that T GF had differential regulatory effects on SG and IG, which could provide a useful reference for cultivation of high-quality rice varieties under global climate change. Besides, the determination of texture properties was a reliable method for taste evaluating of IHs in the breeding process. [Display omitted] • T GF had a significant quadratic function relationship with quality of IHs. • T GF ranging from 23.3 to 25.2 °C could improve the quality of IHs. • The optimal T GF of IG was 2.3–4.2 °C higher than that of SG. • Texture properties can effectively evaluate the eating quality of IHs. • The TV of IG was higher than SG at T GF greater than 24 °C, mainly due to higher elasticity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Static magnetic field (SMF) could improve the frozen quality of rice dumpling. • SMF accelerated freezing rate and shortened phase transition of water. • SMF-assisted freezing restricted the transition of bound water to free water. • SMF-assisted freezing showed less damage on rice starch granules. • SMF-assisted freezing improved the physicochemical properties of rice flour. This study aimed to investigate the effect of static magnetic field (SMF, 0–10 mT) on the quality of rice dumplings subjected to 7, 14, 21, and 28 freeze–thaw cycles. The underlying mechanism was explored by monitoring changes in water phase transition, water distribution, and structural and physicochemical properties of rice flour. Results suggested that SMF enables the formation of small ice crystals by accelerating freezing rate, shortening phase transition time, and increasing bound water content, which attributes to reducing the mechanical damage on starch granules and thus improves the quality of frozen rice dumpling. After 7–28 freeze–thaw cycles, SMF treatment increased the whiteness by 0.08–1.58, reduced the cracking ratio by 1.67 %–8.34 %, decreased the water loss ratio by 0–0.75 %, and significantly improved the texture of cooked rice dumplings. This study confirmed the feasibility of SMF in improving the quality of rice dumpling, which contributes to expanding the applications of magnetic freezer in the preservation of starch-based foods. [ABSTRACT FROM AUTHOR]

High throughput plant phenomics enables precise quantification of structural information for the complex crop canopy. Leaf to panicle ratio (LPR) in terms of light interception is a physiological trait we formerly developed to clarify the light distribution pattern within the canopy of japonica rice. Here, using the methodology of deep learning neural network (Transformer Feature Pyramid Network), we proposed a general method for LPR calculation for both japonica and indica rice, and tested it in the study on variation of canopy structure across nitrogen (N) fertilization modes. Field experiments over three years (2020–2022) with three nitrogen levels and two basal to topdressing ratios were conducted for two cultivars of each japonica and indica rice. Results showed contrasting dynamic variation of LPR between the two species, ascending for indica rice but descending for japonica rice along with the grain-filling progression. Indica rice had larger temporal variation in LPR than the japonica. N topdressing significantly increased the LPR of indica rice cultivars at same N level, whereas that of japonica was dependent on N level and genotype. Morphological measurement revealed that the differential response of LPR to N was associated with the height difference between the flag leaf and panicle, panicle curvature, leaf area index and panicle area index. Correlation analysis revealed that the relation between LPR and grain yield was significantly positive for indica rice but negative for japonica rice. Our findings suggest that LPR can effectively reflect the characteristics of canopy structure as affected by cultivars and fertilization modes, thus being a valuable physiological indicator for crop science. • LPR (leaf to panicle ratio) was used to compare the canopy structure between japonica and indica rice. • The two subspecies were contrasting in the dynamics of canopy structure. • LPR of indica rice was more sensitive to nitrogen topdressing. • LPR and yield was positively related for indica but negatively for japonica. [ABSTRACT FROM AUTHOR]

Plant phenomics is a new avenue for linking plant genomics and environmental studies, thereby improving plant breeding and management. Remote sensing techniques have improved high-throughput plant phenotyping. However, the accuracy, efficiency, and applicability of three-dimensional (3D) phenotyping are still challenging, especially in field environments. Light detection and ranging (lidar) provides a powerful new tool for 3D phenotyping with the rapid development of facilities and algorithms. Numerous efforts have been devoted to studying static and dynamic changes of structural and functional phenotypes using lidar in agriculture. These progresses also improve 3D plant modeling across different spatial–temporal scales and disciplines, providing easier and less expensive association with genes and analysis of environmental practices and affords new insights into breeding and management. Beyond agriculture phenotyping, lidar shows great potential in forestry, horticultural, and grass phenotyping. Although lidar has resulted in remarkable improvements in plant phenotyping and modeling, the synthetization of lidar-based phenotyping for breeding and management has not been fully explored. We identify three main challenges in lidar-based phenotyping development: 1) developing low cost, high spatial–temporal, and hyperspectral lidar facilities, 2) moving into multi-dimensional phenotyping with an endeavor to generate new algorithms and models, and 3) embracing open source and big data. [ABSTRACT FROM AUTHOR]

The redistribution of nonstructural carbohydrates (NSCs) in rice (Oryza sativa) sheaths contributes greatly to grain filling. Sucrose nonfermenting-1-related protein kinase 1 (SnRK1) regulates sheath-to-panicle transport of NSCs during rice grain filling; however, it is unknown whether elevated activity of SnRK1 in sheaths improves NSC transport and grain filling. Expression of OsSnRK1a is mainly responsible for regulating SnRK1 activity in rice sheaths. Analysis of transgenic rice plants containing the OsSnRK1a promoter::GUS construct indicated that OsSnRK1a is widely expressed in rice. Notably, OsSnRK1a is highly expressed in mesophyll cells of sheaths. Therefore, a green tissue promoter specifically expressed in sheaths and leaf parenchyma cells and phloem tissue was used to over-express OsSnRK1a in japonica rice. The transgenic lines exhibited increased SnRK1a expression and SnRK1 activity in sheaths. The NSC and starch in the transgenic lines and WT all showed accumulation before heading and during the early-filling stage, and declining at the peak filling stage. But the starch and NSC content in transgenic lines was lower than that of WT. Moreover, the transgenic lines showed lower sucrose contents and higher sucrose efflux rates. The accelerated sheath NSC transport improved grain filling, and stimulated panicle development in transgenic lines. SnRK1a expression and SnRK1 activity were also increased in the leaves of transgenic lines, which improved leaf photosynthetic activity and contributed to optimal grain filling and panicle development. These results verify the promotion of high SnRK1 activity in sheath NSC transport, and also provide a new approach to improving sheath NSC transport and rice yield. • OsSnRK1a is highly expressed in mesophyll cells of sheaths. • The PP promoter was used increased SnRK1a expression and SnRK1 activity in sheaths of transgenic lines. • Elevated SnRK1 activity in sheaths accelerated NSC transport in transgenic lines, thereby improving grain filling and final yield. • SnRK1 activity and the photosynthetic rate were also increased in leaves of the transgenic lines. [ABSTRACT FROM AUTHOR]

Rice glutelin is sensitive to temperature and nitrogen, however, the regulatory mechanism of glutelin response to temperature and nitrogen is unclear. In this study, we conducted the open field warming experiment by the Free-air temperature enhancement facility and application of nitrogen during grain filling. In three-year field warming experiments, glutelin relative content was significantly increased under elevated temperature and application of nitrogen. Temperature and nitrogen and their interaction increased the glutelin accumulation rate in the early and middle grain filling stages (10-25d after flowering), but decreased the glutelin accumulation rate in the middle and late grain filling stages (25-45d after flowering). Elevated temperature promoted pro-glutelin levels whereas application of nitrogen under warming increased the amount of α-glutelin. At the transcriptional level, the expression levels of the glutelin-encoding genes and protein disulphide isomerase-like enzyme (PDIL1-1), glutelin precursor accumulation 4 (GPA4), glutelin precursor mutant 6 (GPA2), glutelin precursor accumulation 3 (GPA3) and vacuolar processing enzyme (OsVPE1) of glutelin folding, transport and accumulation-related genes were up-regulated by nitrogen under natural temperature as early as 5d after flowering. However, elevated temperature up-regulated glutelin-encoding genes before 20d after flowering, and the expression of endoplasmic reticulum chaperone (OsBip1), OsPDIL1-1 , small GTPase gene (GPA1), GPA2-GPA4 and OsVPE1 were significantly increased post 20d after flowering under warming. In addition, the increase in glutelin content worsened grain quality, particularly chalkiness and eating quality. Overall, the results were helpful to understand glutelin accumulation and provide a theoretical basis for further study the relationship between rice quality and glutelin under global warming. • Elevated temperature and additional nitrogen and their interaction significantly increased the glutelin relative content. • Temperature and nitrogen and their interaction increased the glutelin accumulation rate in the early and mid-filling periods. • Elevated temperature promoted the level of pro-glutelin whereas further additional nitrogen improved the level of α-glutelin. • Glutelin synthesis and maturity were regulated by elevated temperature at 5-20d and 20-30d after flowering, respectively. [ABSTRACT FROM AUTHOR]

Highlights • Increased temperature affects starch anabolism and further affected quality traits. • Under elevated temperature, nitrogen decreased the starch particle-size induced chalky rice. • Nitrogen regulates starch structure to further affect quality under elevated temperature. • Adjusting nitrogen fertilizer use likely mitigates quality deterioration under climate warming. Abstract Relevant evidence of rice quality responses to increased temperatures under field condition has been obtained in our previous study. Understanding the intrinsic mechanism of increased temperatures and fertilizer treatment in regulating rice quality formation will be contributed to the development of mitigation measures suitable for actual field operations and to cope with climate warming. This study investigated the potential role of nitrogen fertilizer in regulating the rice quality under field warming through identifying starch-related property indicators. Results showed application of nitrogen fertilizer at heading stage effectively delayed the significantly increased accumulation of total starch, amylose and amylopectin, and reduced the starch particle size, chain length distribution, and crystal structure induced by high temperature, which further compensated the deterioration of rice quality caused by elevated temperature. [ABSTRACT FROM AUTHOR]

Abstract Due to the sensitivity of chalk formation to high temperatures, the global warming will further threaten the improvement of high chalky grain rate in the southern japonica region of China. There have been many studies reported on the role of starch in the formation of chalkiness, but the relationship between nitrogen metabolites and chalkiness has not been given sufficient attention. In this study, we conducted the open field warming experiment and investigated the effects of temperature increase on grain protein metabolism. Results showed under the warming range of predicted global temperature increase (1.9 °C–4.0 °C), field warming apparently accelerated the development of grain endosperm, and the number of protein bodies were increased in both rice varieties, Furthermore, we clarified that the increased temperature regulated the key regulatory factors in protein synthesis and metabolism pathway, and the synthesis, transport, folding, assembly process of grain protein were further affected, and that further lead the component changes of grain storage protein. In conclusion, chalky traits are closely related to the grain storage materials and in this study, increased temperature induced the changes in the accumulation balance of storage proteins, amino acids and starches, which coordinately controls the formation of grain chalkiness. Highlights • We simulated climate warming with the field-warming system in actual rice field. • Endosperm and protein bodies were apparently increased under elevated temperatures. • Elevated temperature regulated regulatory factors in protein anabolism pathway. • Elevated temperatures affect balance of storage material and induce the chalkiness. • Proteins may play a certain role in chalkiness formation under elevated temperature. [ABSTRACT FROM AUTHOR]