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Reprograming of chromatin structures and changes in gene expression are critical for plant male gamete development, and epigenetic marks play an important role in these processes. Histone variant H3.3 is abundant in euchromatin and is largely associated with transcriptional activation. The precise function of H3.3 in gamete development remains unclear in plants. Here, we report that H3.3 is abundantly expressed in Arabidopsis anthers and its knockout mutant h3.3–1 is sterile due to male sterility. Transcriptome analysis of young inflorescence has identified 2348 genes downregulated in h3.3–1 mutant, among which 1087 target genes are directly bound by H3.3, especially at their 3ʹ ends. As a group, this set of H3.3 targets is enriched in the reproduction-associated processes including male gamete generation, pollen sperm cell differentiation and pollen tube growth. The function of H3.3 in male gamete development is dependent on the Anti-Silencing Factor 1A/1B (ASF1A/1B)-Histone regulator A (HIRA)-mediated pathway. Our results suggest that ASF1A/1B-HIRA-mediated H3.3 deposition at its direct targets for transcription activation forms the regulatory networks responsible for male gamete development. [ABSTRACT FROM AUTHOR]

A highly sensitive pressure-sensitive sensor based on MXene was developed using the electrostatic self-assembly method, with carbide sponges as the elastic substrate and a rational design. Specifically, CTAB was used to treat the carbide triamine sponge and conduct the electrostatic self-assembly with MXene to achieve a tightly combined conductive filler and substrate. The resulting pressure sensor showed excellent performance, with a high sensitivity of 15.05 kPa−1 under a range of 0–20 kPa, a response time of 0.1 s, and high durability under 2000 loading–unloading cycles. The minimum detection limit of the sensor was as low as 0.3 Pa, demonstrating excellent monitoring performance. Additionally, finite-element simulation analysis showed that MXene@CTAB@CMF had even better sensing performance at the same stress level. Moreover, the pressure sensor exhibited good sensing performance for various physiological signals and daily work monitoring of the human body, indicating its potential application value. [ABSTRACT FROM AUTHOR]

Plants cope with various recurring stress conditions that often induce DNA damage, ultimately affecting plant genome integrity, growth, and productivity. The CROWDED NUCLEI (CRWN) family comprises lamin-like proteins with multiple functions, such as regulating gene expression, genome organization, and DNA damage repair in Arabidopsis (Arabidopsis thaliana). However, the mechanisms and consequences of CRWNs in DNA damage repair are largely unknown. Here, we reveal that CRWNs maintain genome stability by forming repairing nuclear bodies at DNA double-strand breaks. We demonstrate that CRWN1 and CRWN2 physically associate with the DNA damage repair proteins RAD51D and SUPPRESSOR OF NPR1-1 Inducible 1 (SNI1) and act in the same genetic pathway to mediate this process. Moreover, CRWN1 and CRWN2 partially localize at γ-H2AX foci upon DNA damage. Notably, CRWN1 and CRWN2 undergo liquid–liquid phase separation to form highly dynamic droplet-like structures with RAD51D and SNI1 to promote the DNA damage response (DDR). Collectively, our data shed light on the function of plant lamin-like proteins in the DDR and maintenance of genome stability. CROWDED NUCLEI proteins associate with γ-H2AX foci and interact with SUPPRESSOR OF NPR1-1 INDUCIBLE 1 and RAD51D to ensure effective DNA damage repair and maintenance of genome stability. [ABSTRACT FROM AUTHOR]

Extreme environmental changes threaten plant survival and worldwide food production. In response to osmotic stress, the plant hormone abscisic acid (ABA) activates stress responses and restricts plant growth. However, the epigenetic regulation of ABA signaling and crosstalk between ABA and auxin are not well known. Here, we report that the histone variant H2A.Z -knockdown mutant in Arabidopsis Col-0, h2a.z-kd , has altered ABA signaling and stress responses. RNA-sequencing data showed that a majority of stress-related genes are activated in h2a.z-kd. In addition, we found that ABA directly promotes the deposition of H2A.Z on SMALL AUXIN UP RNA s (SAUR s), and that this is involved in ABA-repression of SAUR expression. Moreover, we found that ABA represses the transcription of H2A.Z genes through suppressing the ARF7/19–HB22/25 module. Our results shed light on a dynamic and reciprocal regulation hub through H2A.Z deposition on SAUR s and ARF7/19–HB22/25-mediated H2A.Z transcription to integrate ABA/auxin signaling and regulate stress responses in Arabidopsis. [ABSTRACT FROM AUTHOR]

Summary: Auxin is a critical phytohormone that is involved in the regulation of most plant growth and developmental responses. In particular, epigenetic mechanisms, like histone modifications and DNA methylation, were reported to affect auxin biosynthesis and transport. However, the involvement of other epigenetic factors, such as histone variant H2A.Z, in the auxin‐related developmental regulation remains unclear.We report that the histone variant H2A.Z knockdown mutant in Arabidopsis Col‐0 ecotype, h2a.z‐kd, has more lateral roots and weak gravitational responses related to auxin‐regulated growth performances. Further study revealed that auxin promotes the eviction of H2A.Z from the auxin‐responsive genes SMALL AUXIN‐UP RNAs (SAURs) to activate their transcriptions.We found that IAA promotes the transcription of H2A.Z genes through HOMEOBOX PROTEIN 22/25 (AtHB22/25) transcription factors which work as downstream targets of ARF7/19 in auxin signaling. Double mutant of hb22 hb25 showed similar lateral root and gravitropism phenotypes to h2a.z‐kd.Our results shed light on a reciprocal regulation hub through INOSITOL AUXOTROPHY 80‐mediated H2A.Z eviction and ARF7/19‐HB22/25‐mediated H2A.Z transcription to modulate the activation of SAURs and plant growth in Arabidopsis. [ABSTRACT FROM AUTHOR]

B-box transcription factors (BBXs) are important regulators of flowering, photomorphogenesis, shade-avoidance, abiotic and biotic stresses and plant hormonal pathways. In Arabidopsis, 32 BBX proteins have been identified and classified into five groups based on their structural domains. Little is known about the fifth group members (BBX26–BBX32) and the detailed molecular mechanisms relevant to their functions. Here we identified B-box transcription factor 28 (BBX28) that interacts with Constans (CO), a transcriptional activator of Flowering Locus T (FT). Overexpressing BBX28 leads to late flowering with dramatically decreased FT transcription, and bbx28 deficient mutant displays a weak early flowering phenotype under long days (LD), indicating that BBX28 plays a negative and redundant role in flowering under LD. Additionally, the interaction between BBX28 and CO decreases the recruitment of CO to FT locus without affecting the transcriptional activation activity of CO. Moreover, the N-terminal cysteines, especially those within the B-box domain, are indispensable for the heterodimerization between BBX28 and CO and activation of CO on FT transcription. Genetic evidences show that the later flowering caused by BBX28 overexpression is compromised by CO ectopic expression. Collectively, these results supported that BBX28 functions with CO and FT to negatively regulate Arabidopsis flowering, in which the N-terminal conserved cysteines of BBX28 might play a central role. [ABSTRACT FROM AUTHOR]

Highlights • Various land use patterns had a significant impact on nutrients loss via surface runoff. • Irrigated rice paddies had a higher level of self-sustainability of grain production compared with rain-fed uplands. • Implications for integrating agricultural and environmental management strategies. Abstract Agricultural land use on slope areas is susceptible to nutrition loss via surface runoff, which would result in negative impacts on downstream waters. However, the linkage between nutrition loss and off-site crop production has been rarely reported. A study was conducted in a small independent agroforestry watershed in subtropical hilly terrain of China. Nutrition loss via surface runoff was measured from cropland, tea garden, citrus orchard, and natural woodland on a slope area. Grain production of rain-fed uplands and irrigated rice paddies were also investigated. Results exhibited that the runoff and associated nutrient loss were substantially affected by land use patterns. In general, the cropland generated the highest runoff and associated nutrient loss, followed by tea garden, citrus orchard, and woodland. Despite of land use patterns, the descending order of nutrient elements losses was: Ca2+ > K+ > SO 4 -S > TN (total nitrogen) > Mg2+ > TP (total phosphorus). Irrigated rice paddies had a higher level of self-sustainability of grain production compared with rain-fed uplands, which should be partially attributed to the nutrients input from irrigated water. The results imply that the runoff harvesting for irrigation, especially the runoff harvesting from agricultural land use patterns, can increase crop production with extra nutrition input by irrigation and reduce nutrition load to downstream waters. [ABSTRACT FROM AUTHOR]

Abstract Water and organic amendments are the two most important factors that control methane (CH 4) emissions from rice fields, the combined effect of which on CH 4 emissions has been rarely studied. Thus, a field experiment in a split-plot design was conducted to investigate the combined effect of straw and water management on CH 4 emissions. Main plots had water treatments: continuous flooding (CF), flooding – midseason drying – flooding (FDF), and flooding for transplanting – rainfed (RF); and subplots had straw treatments: straw incorporated into soil (SI), straw mulching (SM), and without straw. Results showed that the presence of water layer led to substantial increase in CH 4 emissions which were enhanced by straw application. Cumulative CH 4 emissions were influenced by water, straw, and their interactions significantly (P < 0.05). The cumulative CH 4 emissions were 505.3, 241.2, and 56.5 kg ha−1 for CF, FDF, and RF, respectively. By contrast, SI under CF, FDF, and RF increased CH 4 emissions by 265.4, 271.4, and 175.6 kg ha−1, respectively. And SM under CF, FDF, and RF increased CH 4 emissions by 213.3, 112.8, and 14.6 kg ha−1, respectively. The results indicated that SM resulted in less CH 4 emissions compared with SI, especially in plots frequently with absence of water layer. Besides, SM had a potential to increase rice yield in rice paddies that had a lack of water. Therefore, in-season straw application should be avoided in lowland rice paddies, and straw mulching is practical in rice paddies lack of water. Highlights • Cumulative CH 4 emissions were influenced by water, straw, and their interactions. • Straw mulching resulted in less CH 4 emissions compared with straw incorporation. • In-season straw application should be avoided especially in lowland rice paddies. • Straw mulching is practical in rice paddies that have a lack of water. [ABSTRACT FROM AUTHOR]

A two-year field investigation was conducted in a typical double rice region in South China. The treatments included conventional dose of nitrogen, phosphorus, and potassium fertilizers (NPKc); reduced chemical fertilizer combined with straw retention (NPKr+S); and no fertilizer as a control (CK). The global warming potential (GWP) was evaluated with nitrous oxide (N2O) and methane (CH4) emissions. The results showed that fertilization enhanced not only CH4 but also N2O emissions. For CK, NPKc, and NPKr+S, respectively, annual N2O emissions were 0.09, 0.47, and 0.33 kg ha−1; and annual CH4 emissions were 562.4, 657.9, and 882.2 kg ha−1. Consequently, the GWPs were 19,146, 22,507, and 30,094 kg CO2-eqv ha−1 year−1 for CK, NPKc, and NPKr+S, respectively. As rice grain yields were comparable between NPKc (9332 kg ha−1 year−1) and NPKr+S (9261 kg ha−1 year−1), the greenhouse gas intensity (GHGI) was significantly lower in NPKc compared with that in NPKr+S which induced more GWP. Overall, this study showed the potential of straw retention to reduce chemical fertilizer use. But it increased the GWP by 33.7% and GHGI by 34.7% in double rice systems under continuous flooding regime. [ABSTRACT FROM AUTHOR]

As part of a long-term sloped land use experiment established in 1995 at Taoyuan Agro-ecosystem Research Station (111°26′ E, 28°55′ N) in China, soil samples were collected from three land use types, including cropland (CL), natural forest, and tea plantation. Quantitative polymerase chain reaction and terminal restriction fragment length polymorphism were used to determine the abundance and community composition of amoA-containing bacteria (AOB) and archaea (AOA). The results indicate that land use type induced significant changes in soil potential nitrification rate and community composition, diversity, and abundance of AOB and AOA. Both AOB and AOA community compositions were generally similar between upper and lower slope positions (UP and LP), except within CL. The LP soils had significantly ( p < 0.05) higher diversity and abundance of both AOB and AOA than in the UP. Potential nitrification rate was significantly correlated ( p < 0.05) with diversity and abundance of AOA, but not with AOB. Among land use types, the NO and amoA-containing AOA runoff loss was greatest in CL. Nitrate-N runoff loss was significantly correlated ( p < 0.05) with the loss of AOA amoA copies in the runoff water. Furthermore, relationships between NO-N runoff loss and abundance of AOA but not of AOB at both slope positions were significantly correlated ( p < 0.05). These findings suggest that AOA are more important than AOB in nitrification and NO-N runoff loss in acidic soils across sloped land use types. [ABSTRACT FROM AUTHOR]

□ Fertilization plays an important role in soil fertility and rice yield. A long-term (1990–2006) field experiment was conducted at a typical subtropical hilly agriculture region in south central China. The objectives of this study are to investigate the effects of long-term fertilizations on i) accumulations and distributions of soil carbon (C), nitrogen (N) and phosphorus (P) in different sizes of water-stable aggregates (WSA); ii) dynamic change of soil C, N, and P over years; and iii) the rice yield. Application of organic materials (OM), especially in combination with chemical fertilizers, increased soil organic C (SOC), soil total N (NT), and soil total P (PT) concentrations in all sizes of WSA, and they more concentrated in WSA (>1 mm). However, single chemical fertilizers had little impact on SOC and NT. There were significantly positive correlations between SOC and NTin each size of WSA, (r≥0.977, n = 15,P< 0.01). It illuminated that application of organic materials benefited the conservation of soil nitrogen. However, application of organic materials had less impact on PT. Variation of C/P was larger than C/N. PTwas mainly affected by input of phosphorus. Data over years showed that SOC and NTcontinued to rise, whereas PTtended to decline irrespective of treatments. Furthermore, economical chemical fertilizers application combining with green manure and half straw returning (NPKe+ SR) can produce approximate effects on PTas conventional dose of chemical fertilizers (NPKc). Average rice yield of NPKcfor 17 years was 9399 kg ha−1. Compared with NPKc, OM decreased yield by only 4.4%, which indicated that traditional organic fertilization could obtain relatively high yield. NPKe+ SR obtained approximate yield as NPKcdid, which showed that green manure and half amount of straw effectually reduced chemical fertilizers by about one third. [ABSTRACT FROM AUTHOR]

The in situ application of rice straw enhances CH4 emissions by a large margin. The ex situ application of rice straw in uplands, however, may mitigate total global warming potential (GWP) of CH4 and N2O emissions from paddy-upland coexisting systems. To evaluate the efficiency of this practice, two field trials were conducted in rice-rice-fallow and maize-rape cropping systems, respectively. Year-round measurements of CH4 and N2O emissions were conducted to evaluate the system-scaled GWP. The results showed that CH4 accounted for more than 98% of GWP in paddy. Straw removal from paddy decreased 44.7% (302.1 kg ha−1 yr−1) of CH4 emissions and 51.2% (0.31 kg ha−1 yr−1) of N2O emissions, thus decreased 44.8% (7693 kg CO2-eqv ha−1 yr−1) of annual GWP. N2O accounted for almost 100% of GWP in upland. Straw application in upland had insignificant effects on CH4 and N2O emissions, which increased GWP only by 91 kg CO2-eqv ha−1 yr−1. So, the transfer of straw from paddy to upland could decrease GWP by 7602 kg CO2-eqv ha−1 yr−1. Moreover, straw retention during late rice season contributed to 88.2% of annual GWP increment. It is recommended to transfer early rice straw to upland considering GWP mitigation, nutrient recycling and labor cost. [ABSTRACT FROM AUTHOR]