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Dihydrogibberellin (DIH) is an eco‐friendly and low‐toxic regulator with immense potential for application in the current rice industry, specifically for increasing yield and lodging resistance. However, limited research has been conducted to explore the impact of DIH on the yield and lodging resistance of direct‐seeded rice (DSR, Oryza sativa L.). Therefore, a 2‐year field experiment was conducted to evaluate the effects of spraying different concentrations of 5% DIH emulsifiable concentrate on DSR during the tillering (1) and jointing (2) stages. Three concentrations of DIH were used: 27 (DIH27), 54 (DIH54), and 108 g ha−1 (DIH108). The commonly used paclobutrazol concentration in rice production (112.5 g ha−1) was compared and a clear water treatment was used as control (CK). The results of the experiment showed that the DIH treatments increased the DSR yield by 1.22%–22.64% and reduced lodging index by 8.9%–54.2% compared to the CK treatment. Additionally, the DIH treatments resulted in significant reductions in the length of the 1–3 basal internodes and plant height, as well as increases in the diameter and culm wall thickness of internodes. Moreover, the DIH treatments also led to higher dry matter percentages in stalks and leaf sheaths, as well as increased lignin and cellulose content. Furthermore, the best effect of DIH application was observed at the jointing stage in terms of increasing yield and lodging resistance. Therefore, this research demonstrates that the application of DIH to DSR at the jointing stage can be an effective strategy for increasing yield and improving lodging resistance. Core Ideas: Spraying dihydrogibberellin effectively improved the lodging resistance of direct‐seeded rice.Spraying dihydrogibberellin at jointing stage can significantly boost the lodging resistance of direct‐seeded rice.The lodging and rice grain yield effects of dihydrogibberellin and paclobutrazol are compared. [ABSTRACT FROM AUTHOR]

Water uptake is crucial for crop growth and development and drought stress tolerance. The water channel aquaporins (AQP) play important roles in plant water uptake. Here, we discovered that a jasmonic acid analog, coronatine (COR), enhanced maize (Zea mays) root water uptake capacity under artificial water deficiency conditions. COR treatment induced the expression of the AQP gene Plasma membrane intrinsic protein 2;5 (ZmPIP2;5). In vivo and in vitro experiments indicated that COR also directly acts on ZmPIP2;5 to improve water uptake in maize and Xenopus oocytes. The leaf water potential and hydraulic conductivity of roots growing under hyperosmotic conditions were higher in ZmPIP2;5‐overexpression lines and lower in the zmpip2;5 knockout mutant, compared to wild‐type plants. Based on a comparison between ZmPIP2;5 and other PIP2s, we predicted that COR may bind to the functional site in loop E of ZmPIP2;5. We confirmed this prediction by surface plasmon resonance technology and a microscale thermophoresis assay, and showed that deleting the binding motif greatly reduced COR binding. We identified the N241 residue as the COR‐specific binding site, which may activate the channel of the AQP tetramer and increase water transport activity, which may facilitate water uptake under hyperosmotic stress. [ABSTRACT FROM AUTHOR]

We developed a facile, efficient method for synthesizing highly substituted 2‐aminopyridines from unstable vinyl carbodiimides generated in situ in a one‐pot transformation. A series of novel highly substituted 3‐functionalized 2‐aminopyridines were produced in good yields. Reaction mechanism studies, which included control experiments and density‐functional theory (DFT) calculations, demonstrated that Rh and potassium carbonate played key roles in the cyclization step. [ABSTRACT FROM AUTHOR]

Miscanthus × giganteus has attracted much attention and occupied a significant niche as a bioenergy crop to meet the world's energy demand and in the fight against climate change. In this study, a field experiment was conducted to evaluate the yield and biomass characteristics of M. × giganteus over a period of three years from 2013 to 2015 in Beijing, China. M. × giganteus plants showed higher tiller density and litter leaf weight in the third year, whereas no significant difference in plant height was observed among the years. In contrast, a larger number of nodes per plant were recorded in the first year. Biomass yield potential was the highest in the third year (42.3 t ha−1). In addition, plant height (r =.594, p =.042), tiller density (r =.854, p <.01), and number of nodes per plant (r = ‐.589, p =.044) were significantly correlated with biomass yield. Contents of cellulose and lignin were higher in stems, while that of hemicellulose and ash were higher in leaves. M. × giganteus biomass may be used for cellulosic ethanol conversion due to high cellulose and hemicellulose contents and low lignin content and for direct combustion and co‐combustion due to high calorific value (18.5 MJ kg−1). To conclude, our findings indicate that M. × giganteus can be cultivated in northern China as an excellent herbaceous bioenergy crop. Rational utilization of the agronomic characteristics would be helpful to screening and breeding bioenergy grass for promoting bioenergy production in China. Core ideas: Miscanthus × giganteus is suitable for cultivation in northern China.Agronomic traits were significantly correlated with biomass yield.Biomass yield of M. × giganteus increased over a period of three years.Biomass quality exhibited better suitability for ethanol production.High calorific value may be used for direct combustion and co‐combustion. [ABSTRACT FROM AUTHOR]

BACKGROUND: Picolinate/picolinic acid compounds are an important class of synthetic auxin herbicides. To explore the herbicidal activity of 6‐pyrazolyl picolinate compounds, a series of 3‐chloro‐6‐pyrazolyl‐picolinate derivatives was designed and synthesized. RESULTS: Twenty‐five 3‐chloro‐6‐pyrazolyl‐picolinate derivatives synthesized were tested for herbicidal activity and the IC50 value of compound c5 to the growth of Arabidopsis thaliana root was 27 times lower than that of the commercial herbicide clopyralid. Compound c5 displayed better post‐emergence herbicidal activity and broader (Picloram, Clopyralid, Aminopyralid) herbicidal spectrum at a dosage of 400 g ha−1 in comparison with clopyralid; it also was safe to wheat and maize at this dosage. Arabidopsis thaliana phenotypes and expression of auxin‐response genes demonstrated that compound c5 might be a novel auxin‐type herbicide. Molecular docking analyses revealed that compound c5 had stronger binding ability to receptor AFB5 (auxin signaling F‐box protein 5) than clopyralid. CONCLUSION: These 6‐pyrazolyl picolinate compounds could be used as potential lead structures for the discovery of a novel synthetic auxin herbicide. © 2021 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND: The use of exo‐16,17‐dihydro‐gibberellin A5‐13‐acetate (DHGA5) in agriculture has been limited by its low synthetic yield. This study was aimed at optimizing the synthetic route of DHGA5, designing and synthesizing new derivatives with strong plant growth inhibitory activities. RESULTS: Previous synthetic methods were replaced with a shorter, milder and faster reaction route with higher yield (76.3%) of DHGA5. Based on this novel route, a series of new derivatives were designed and synthesized using DHGA5 as a lead compound and characterized and evaluated for biological activities in Arabidopsis thaliana. Among the 15 tested derivatives, compound 14j showed a lower medium inhibition concentration (IC50, 73 μm) in Arabidopsis than that of DHGA5 (91 μm). Gibberellin deficient mutant assay further revealed that 14j had very different activities compared to DHGA5 as it specifically inhibits gibberellin biosynthetic pathways. In addition, 14j does not influence the interaction between gibberellin receptors (GID1) and the master growth repressor (RGA) based on yeast two‐hybrid assay. CONCLUSION: The optimized synthetic route provides a promising method for large‐scale preparation of DHGA5. Our biological assays indicate that 14j likely acts on gibberellin signaling elements other than GID1. These results indicate that novel plant growth regulators can be developed. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Drought is a key limiting factor for cotton ( Gossypium spp.) production, as more than half of the global cotton supply is grown in regions with high water shortage. However, the underlying mechanism of the response of cotton to drought stress remains elusive., By combining genome-wide transcriptome profiling and a loss-of-function screen using virus-induced gene silencing, we identified Gossypium hirsutum Gh WRKY59 as an important transcription factor that regulates the drought stress response in cotton., Biochemical and genetic analyses revealed a drought stress-activated mitogen-activated protein ( MAP) kinase cascade consisting of Gh MAP3K15-Mitogen-activated Protein Kinase Kinase 4 (GhMKK4)-Mitogen-activated Protein Kinase 6 (GhMPK6) that directly phosphorylates Gh WRKY59 at residue serine 221. Interestingly, Gh WRKY59 is required for dehydration-induced expression of Gh MAPK3K15, constituting a positive feedback loop of Gh WRKY59-regulated MAP kinase activation in response to drought stress. Moreover, Gh WRKY59 directly binds to the W-boxes of DEHYDRATION-RESPONSIVE ELEMENT-BINDING PROTEIN 2 ( Gh DREB2), which encodes a dehydration-inducible transcription factor regulating the plant hormone abscisic acid ( ABA)-independent drought response., Our study identified a complete MAP kinase cascade that phosphorylates and activates a key WRKY transcription factor, and elucidated a regulatory module, consisting of Gh MAP3K15-Gh MKK4-Gh MPK6-Gh WRKY59 -Gh DREB2, that is involved in controlling the cotton drought response. [ABSTRACT FROM AUTHOR]

LOS 5/ ABA 3 gene encoding molybdenum cofactor sulphurase is involved in aldehyde oxidase ( AO) activity in Arabidopsis, which indirectly regulates ABA biosynthesis and increased stress tolerance. Here, we used a constitutive super promoter to drive LOS 5/ ABA 3 overexpression in soybean ( Glycine max L.) to enhance drought tolerance in growth chamber and field conditions. Expression of LOS 5/ ABA 3 was up-regulated by drought stress, which led to increasing AO activity and then a notable increase in ABA accumulation. Transgenic soybean under drought stress had reduced water loss by decreased stomatal aperture size and transpiration rate, which alleviated leaf wilting and maintained higher relative water content. Exposed to drought stress, transgenic soybean exhibited reduced cell membrane damage by reducing electrolyte leakage and production of malondialdehyde and promoting proline accumulation and antioxidant enzyme activities. Also, overexpression of LOS 5/ ABA 3 enhanced expression of stress-up-regulated genes. Furthermore, the seed yield of transgenic plants is at least 21% higher than that of wide-type plants under drought stress conditions in the field. These data suggest that overexpression of LOS 5/ ABA 3 could improve drought tolerance in transgenic soybean via enhanced ABA accumulation, which could activate expression of stress-up-regulated genes and cause a series of physiological and biochemical resistant responses. [ABSTRACT FROM AUTHOR]

Depletion of the ozone layer leads to increasing UV-B radiation on the earth's surface, which may affect weeds and their responses to herbicides. However, the effect of increased UV-B radiation on weeds and the interaction of weeds and herbicides are still obscure. The objective of this study was to compare glyphosate efficacy on velvetleaf that was grown under with and without increased UV-B radiation. Leaf area, dry weight and net photosynthesis of velvetleaf seedlings were adversely affected by increased UV-B radiation. Leaf cuticle wax significantly increased by 28% under increased UV-B radiation. Glyphosate efficacy on velvetleaf, evaluated by shoot dry weight, was significantly decreased by increased UV-B radiation. Exposure to increased UV-B radiation significantly decreased 14C-glyphosate absorption from 49% to 43%, and also resulted in less 14C-glyphosate translocation out of treated leaves and less glyphosate accumulation in newly expanded leaves. The decrease in glyphosate efficacy was due to changes in absorption and distribution, which were attributed to increased cuticle wax and decreased photosynthesis caused by increased UV-B radiation. These results suggest that the responses of weeds to herbicides may be affected by increased UV-B radiation, to the extent that higher rates may be required to achieve the desired effects. [ABSTRACT FROM AUTHOR]

With the aim to determine whether coronatine (COR) alleviates drought stress on wheat, two winter wheat ( Triticum aestivum L.) cultivars, ChangWu134 (drought-tolerant) and Shan253 (drought-sensitive) were studied under hydroponic conditions. Seedlings at the three-leaf stage were cultured in a Hoagland solution containing COR at 0.1 μM for 24 h, and then exposed to 20% polyethylene glycol 6000 (PEG-6000). Under simulated drought (SD), COR increased the dry weight of shoots and roots of the two cultivars significantly; the root/shoot ratio also increased by 30% for Shan253 and 40% for ChangWu134. Both cultivars treated with COR under SD (0.1COR+PEG) maintained significantly higher relative water content, photosynthesis, transpiration, intercellular concentration of CO2 and stomatal conductance in leaves than those not treated with PEG. Under drought, COR significantly decreased the relative conductivity and malondialdehyde production, and the loss of 1,1-diphenyl-2-picrylhydrazyl scavenging activity in leaves was significantly alleviated in COR-treated plants. The activity of peroxidase, catalase, glutathione reductase and ascorbate peroxidase were adversely affected by drought. Leaves of plants treated with COR under drought produced less abscisic acid (ABA) than those not treated. Thus, COR might alleviate drought effects on wheat by reducing active oxygen species production, activating antioxidant enzymes and changing the ABA level. [ABSTRACT FROM AUTHOR]

Weed tolerance of UV-B radiation varies with species, and the radiation could affect weed ecology and management. Variations in growth, photosynthesis and defense system among four important agronomic weeds, Abutilon theophrasti Medik, Amaranthus retroflexus L., Digitaria sanguinalis (L.) Scop and Chloris virgata Swartz, under increased UV-B radiation (ambient and increased radiation at 2.7, 5.4 and 10.8 kJ-m−2-d−1) were studied in the greenhouse experiment. After 2 weeks of radiation, the shoots’dry mass decreased with increasing UV-B radiation except for D. sanguinalis. The reduction in biomass was the result of changes in morphology and physiology. Higher levels of UV-B treatment decreased the leaf area, plant height, net photosynthetic rate and chlorophyll contents, while it increased the contents of wax and UV-B absorbing compound in all species, except for A. retroflexus, which did not increase significantly. The activity of superoxide dismutase, catalase, ascorbate peroxide and the content of ascorbic acid changed differently among the weed species as UV-B radiation increased. D. sanguinalis was the most tolerant and A. retroflexus the most sensitive to increased UV-B radiation. The results also show that the two grass species (D. sanguinalis and C. virgata) were more tolerant to UV-B radiation than the two broad-leafed species (A. theophrasti and A. retroflexus). The UV-B absorbing compound and leaf wax played important roles against UV-B damages in the two grass weeds. The overall results suggest that weed community, competition and management will be altered by continuous ozone depletion. (Handling editor: Li-Xin Zhang) [ABSTRACT FROM AUTHOR]