TaCDPK1-5A positively regulates drought response through modulating osmotic stress responsive-associated processes in wheat (Triticum aestivum).

KEY MESSAGE: Wheat TaCDPK1-5A plays critical roles in mediating drought tolerance through regulating osmotic stress-associated physiological processes. Calcium (Ca2+) acts as an essential second messenger in plant signaling pathways and impacts plant abiotic stress responses. This study reported the function of TaCDPK1-5A, a calcium-dependent protein kinase (CDPK) gene in T. aestivum, in mediating drought tolerance. TaCDPK1-5A sensitively responded to drought and exogenous abscisic acid (ABA) signaling, displaying induced transcripts in plants under drought and ABA treatments. Yeast two-hybrid and co-immunoprecipitation assays revealed that TaCDPK1-5A interacts with the mitogen-activated protein kinase TaMAPK4-7D whereas the latter with ABF transcription factor TaABF1-3A, suggesting that TaCDPK1-5A constitutes a signaling module with above partners to transduce signals initiated by drought/ABA stressors. Overexpression of TaCDPK1-5A, TaMAPK4-7D and TaABF1-3A enhanced plant drought adaptation by modulating the osmotic stress-related physiological indices, including increased osmolyte contents, enlarged root morphology, and promoted stomata closure. Yeast one-hybrid assays indicated the binding ability of TaABF1-3A with promoters of TaP5CS1-1B, TaPIN3-5A, and TaSLAC1-3-2A, the genes encoding P5CS enzyme, PIN-FORMED protein, and slow anion channel, respectively. ChIP-PCR and transcriptional activation assays confirmed that TaABF1-3A regulates these genes at transcriptional level. Moreover, transgene analysis indicated that these stress-responsive genes positively regulated proline biosynthesis (TaP5CS1-1B), root morphology (TaPIN3-5A), and stomata closing (TaSLAC1-3-2A) upon drought signaling. Positive correlations were observed between yield and the transcripts of TaCDPK1-5A signaling partners in wheat cultivars under drought condition, with haplotype TaCDPK1-5A-Hap1 contributing to improved drought tolerance. Our study concluded that TaCDPK1-5A positively regulates drought adaptation and is a valuable target for molecular breeding the drought-tolerant cultivars in T. aestivum.

A WUSCHEL-related homeobox transcription factor, SlWOX4, negatively regulates drought tolerance in tomato.

KEY MESSAGE: CRISPR/Cas9-mediated knockout of SlWOX4 gene in tomato enhances tolerance to drought stress. Drought stress is one of the major abiotic factors that seriously affects plant growth and crop yield. WUSCHEL-related homeobox (WOX) transcription factors are involved in plant growth, development and stress response. However, little is known about the role of WOX genes in drought tolerance in tomato. Here, SlWOX4, a member of the WOX family in tomato, was functionally characterized in mediating drought tolerance. SlWOX4 was homologous to Nicotiana tabacum NtWOX4 with a conserved HD domain, and was localized in the nucleus. SlWOX4 was significantly down-regulated by drought and abscisic acid (ABA) treatments. The loss-of-function mutations of SlWOX4 produced using the CRISPR-Cas9 system in tomato improved drought tolerance by reducing water loss rate and enhancing stomatal closure. In addition, the wox4 lines exhibited reduced accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA), increased antioxidant enzyme activity, proline contents and ABA contents under drought stress. Moreover, gene editing of SlWOX4 in tomato enhanced drought tolerance by regulating the expression of genes encoding antioxidants and ABA signaling molecules. In summary, SlWOX4 gene might negatively regulate drought stress tolerance in tomato and has great potential as a drought-resistant crop-breeding target genes.

Elucidation of AsANS controlling pigment biosynthesis in Angelica sinensis through hormonal and transcriptomic analysis.

Angelica sinensis, a traditional Chinese medicinal plant, has been primarily reported due to its nutritional value. Pigmentation in this plant is an important appearance trait that directly affects its commercial value. To understand the mechanism controlling purpleness in A. sinensis, hormonal and transcriptomic analyses were performed in three different tissues (leave, root and stem), using two cultivars with contrasting colors. The two-dimensional data set provides dynamic hormonal and gene expression networks underpinning purpleness in A. sinensis. We found abscisic acid as a crucial hormone modulating anthocyanin biosynthesis in A. sinensis. We further identified and validated 7 key genes involved in the anthocyanin biosynthesis pathway and found a specific module containing ANS as a hub gene in WGCNA. Overexpression of a candidate pigment regulatory gene, AsANS (AS08G02092), in transgenic calli of A. sinensis resulted in increased anthocyanin production and caused purpleness. Together, these analyses provide an important understanding of the molecular networks underlying A. sinensis anthocyanin production and its correlation with plant hormones, which can provide an important source for breeding.

Stabilization of dimeric PYR/PYL/RCAR family members relieves abscisic acid-induced inhibition of seed germination.

Abscisic acid (ABA) is the primary preventing factor of seed germination, which is crucial to plant survival and propagation. ABA-induced seed germination inhibition is mainly mediated by the dimeric PYR/PYL/RCAR (PYLs) family members. However, little is known about the relevance between dimeric stability of PYLs and seed germination. Here, we reveal that stabilization of PYL dimer can relieve ABA-induced inhibition of seed germination using chemical genetic approaches. Di-nitrobensulfamide (DBSA), a computationally designed chemical probe, yields around ten-fold improvement in receptor affinity relative to ABA. DBSA reverses ABA-induced inhibition of seed germination mainly through dimeric receptors and recovers the expression of ABA-responsive genes. DBSA maintains PYR1 in dimeric state during protein oligomeric state experiment. X-ray crystallography shows that DBSA targets a pocket in PYL dimer interface and may stabilize PYL dimer by forming hydrogen networks. Our results illustrate the potential of PYL dimer stabilization in preventing ABA-induced seed germination inhibition.

Bilberry metabolomic and proteomic profiling during fruit ripening reveals key dynamics affecting fruit quality.

Bilberry (Vaccinium myrtillus L.) is a wild berry species that is prevalent in northern Europe. It is renowned and well-documented for its nutritional and bioactive properties, especially due to its anthocyanin content. However, an overview of biological systems governing changes in other crucial quality traits, such as size, firmness, and flavours, has received less attention. In the present study, we investigated detailed metabolomic and proteomic profiles at four different ripening stages of bilberry to provide a comprehensive understanding of overall quality during fruit ripening. By integrating omics datasets, we revealed a novel global regulatory network of plant hormones and physiological processes occurring during bilberry ripening. Key physiological processes, such as energy and primary metabolism, strongly correlate with elevated levels of gibberellic acids, jasmonic acid, and salicylic acid in unripe fruits. In contrast, as the fruit ripened, processes including flavour formation, cell wall modification, seed storage, and secondary metabolism became more prominent, and these were associated with increased abscisic acid levels. An indication of the increase in ethylene biosynthesis was detected during bilberry development, raising questions about the classification of non-climacteric and climacteric fruits. Our findings extend the current knowledge on the physiological and biochemical processes occurring during fruit ripening, which can serve as a baseline for studies on both wild and commercially grown berry species. Furthermore, our data may facilitate the optimization of storage conditions and breeding programs, as well as the future exploration of beneficial compounds in berries for new applications in food, cosmetics, and medicines.

bZIP Transcription Factor PavbZIP6 Regulates Anthocyanin Accumulation by Increasing Abscisic Acid in Sweet Cherry.

Basic leucine zipper (bZIP) transcription factors (TFs) play a crucial role in anthocyanin accumulation in plants. In addition to bZIP TFs, abscisic acid (ABA) increases anthocyanin biosynthesis. Therefore, this study aimed to investigate whether bZIP TFs are involved in ABA-induced anthocyanin accumulation in sweet cherry and elucidate the underlying molecular mechanisms. Specifically, the BLAST method was used to identify bZIP genes in sweet cherry. Additionally, we examined the expression of ABA- and anthocyanin-related genes in sweet cherry following the overexpression or knockdown of a bZIP candidate gene. In total, we identified 54 bZIP-encoding genes in the sweet cherry genome. Basic leucine zipper 6 (bZIP6) showed significantly increased expression, along with increased anthocyanin accumulation in sweet cherry. Additionally, yeast one-hybrid and dual-luciferase assays indicated that PavbZIP6 enhanced the expression of anthocyanin biosynthetic genes (PavDFR, PavANS, and PavUFGT), thereby increasing anthocyanin accumulation. Moreover, PavbZIP6 interacted directly with the PavBBX6 promoter, thereby regulating PavNCED1 to promote abscisic acid (ABA) synthesis and enhance anthocyanin accumulation in sweet cherry fruit. Conclusively, this study reveals a novel mechanism by which PavbZIP6 mediates anthocyanin biosynthesis in response to ABA and contributes to our understanding of the mechanism of bZIP genes in the regulation of anthocyanin biosynthesis in sweet cherry.

Leaf starch degradation by ß-amylase ZmBAM8 influences drought tolerance in maize.

As a typical C4 plant and important crop worldwide, maize is susceptible to drought. In maize, transitory starch (TS) turnover occurs in the vascular bundle sheath of leaves, differing from that in Arabidopsis (a C3 plant). This process, particularly its role in drought tolerance and the key starch-hydrolyzing enzymes involved, is not fully understood. We discovered that the expression of the ß-amylase (BAM) gene ZmBAM8 is highly upregulated in the drought-tolerant inbred line Chang7-2t. Inspired by this finding, we systematically investigated TS degradation in maize lines, including Chang7-2t, Chang7-2, B104, and ZmBAM8 overexpression (OE) and knockout (KO) lines. We found that ZmBAM8 was significantly induced in the vascular bundle sheath by drought, osmotic stress, and abscisic acid. The stress-induced gene expression and chloroplast localization of ZmBAM8 align with the tissue and subcellular sites where TS turnover occurs. The recombinant ZmBAM8 was capable of effectively hydrolyzing leaf starch. Under drought conditions, the leaf starch in ZmBAM8-OE plants substantially decreased under light, while that in ZmBAM8-KO plants did not decrease. Compared with ZmBAM8-KO plants, ZmBAM8-OE plants exhibited increased drought tolerance. Our study provides insights into the significance of leaf starch degradation in C4 crops and contributes to the development of drought-resistant maize.

Exogenous putrescine application imparts salt stress-induced oxidative stress tolerance via regulating antioxidant activity, potassium uptake, and abscisic acid to gibberellin ratio in Zinnia flowers.

This research was conducted to investigate the efficacy of putrescine (PUT) treatment (0, 1, 2, and 4 mM) on improving morphophysiological and biochemical characteristics of Zinnia elegans "State Fair" flowers under salt stress (0, 50, and 100 mM NaCl). The experiment was designed in a factorial setting under completely randomized design with 4 replications. The results showed that by increasing the salt stress intensity, the stress index (SSI) increased while morphological traits such as plant height decreased. PUT treatments effectively recovered the decrease in plant height and flower quality compared to the not-treated plants. Treatment by PUT 2 mM under 50 and 100 mM salt stress levels reduced the SSI by 28 and 35%, respectively, and increased plant height by 20 and 27% compared to untreated plants (PUT 0 mM). 2 mM PUT treatment also had the greatest effect on increasing fresh and dry biomass, number and surface area of leaves, flower diameter, internodal length, leaf relative water content, protein contents, total chlorophyll contents, carotenoids, leaf potassium (K+) content, and K+/Na+ ratio in treated plants compared to untreated control plants. The treatment of 2 mM PUT decreased the electrolyte leakage, leaf sodium (Na+) content, H2O2, malondialdehyde, and proline content. Furthermore, PUT treatments increased the activity of defense-related enzymes including catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), and phenylalanine ammonium lyase (PAL), and reduced the abscisic acid (ABA) content while increased the level of gibberellin (GA) content compared to untreated samples under all different levels of salinity stress. In this research, enhancing the plant's antioxidant system, increasing K+ absorption, K+/Na+ ratio, and reducing the ABA/GA ratio are likely the most important mechanisms of PUT treatment, which improved growth, and maintained the visual quality of zinnia flowers under salt stress conditions.

Analysis of expression characteristics and identification of interaction proteins of transcription factor BnaABI5 in Brassica napus.

Rapeseed is one important oil crop in China. However, its planting benefit is frequently affected by environmental stresses such as drought in the northwest region of China. The abscisic acid(ABA) signaling pathway plays an important role in plant abiotic stress response and tolerance, and ABFs/AREBs(ABA-responsive element binding factors/ABA-responsive element binding proteins) are the core transcription factors that regulate the expression of ABA-responsive genes. To dissect the key transcription factors mediated abiotic stress, we mainly characterized abscisic acid insensitive 5(BnaABI5) in rapeseed, including its subcellular localization, expression pattern in response to various stress and tissue-specific expression analysis, transcriptional activity analysis as well as interaction screening with BnaMPKs(mitogen-activated protein kinases). Our results showed that the BnaABI5-GFP fusion protein was localized in the nucleus, and its transcript level is induced by drought stress and was mainly expressed in the roots of rapeseed. Furthermore, BnaABI5 showed transcriptional activation activity through a yeast transactivation assay and it also activated the promoter activity of EM6 target gene in the transient expression system in tobacco leaves. Moreover, BnaABI5 interacted with BnaMPK6 and BnaMPK13 through BiFC and Y2H analysis. This study preliminarily explored the expression characteristics of transcription factor BnaABI5 and its interaction with BnaMPKs, which might help us for further understanding the function of BnaABI5.

Withania somnifera osmotin (WsOsm) confers stress tolerance in tobacco and establishes novel interactions with the defensin protein (WsDF).

Pathogenesis-related proteins (PR), including osmotins, play a vital role in plant defense, being activated in response to diverse biotic and abiotic stresses. Despite their significance, the mechanistic insights into the role of osmotins in plant defense have not been extensively explored. The present study explores the cloning and characterization of the osmotin gene (WsOsm) from Withania somnifera, aiming to illuminate its role in plant defense mechanisms. Quantitative real-time PCR analysis revealed significant induction of WsOsm in response to various phytohormones e.g. abscisic acid, salicylic acid, methyl jasmonate, brassinosteroids, and ethrel, as well as biotic and abiotic stresses like heat, cold, salt, and drought. To further elucidate WsOsm's functional role, we overexpressed the gene in Nicotiana tabacum, resulting in heightened resistance against the Alternaria solani pathogen. Additionally, we observed enhancements in shoot length, root length, and root biomass in the transgenic tobacco plants compared to wild plants. Notably, the WsOsm- overexpressing seedlings demonstrated improved salt and drought stress tolerance, particularly at the seedling stage. Confocal histological analysis of H2O2 and biochemical studies of antioxidant enzyme activities revealed higher levels in the WsOsm overexpressing lines, indicating enhanced antioxidant defense. Furthermore, a pull-down assay and mass spectrometry analysis revealed a potential interaction between WsOsm and defensin, a known antifungal PR protein (WsDF). This suggests a novel role of WsOsm in mediating plant defense responses by interacting with other PR proteins. Overall, these findings pave the way for potential future applications of WsOsm in developing stress-tolerant crops and improving plant defense strategies against pathogens.

Exogenous melatonin enhances the continuous cropping tolerance of Tartary buckwheat (Fagopyrum tataricum) by regulating the antioxidant defense system.

The yield of Tartary buckwheat is significantly affected by continuous cropping. Melatonin plays a crucial role in plant defense mechanisms against abiotic stresses. However, the relationship between melatonin and continuous cropping tolerance remains unclear. This study aimed to analyze the physiological mechanism of melatonin in enhancing the continuous cropping tolerance (abiotic stress) of Tartary buckwheat. A field experiment was conducted on Tartary buckwheat cultivar Jinqiao 2 under continuous cropping with five melatonin application rates, 0 (Control), 10, 50, 100, and 200 µmol L-1, applied during the early budding stage. The chlorophyll content, antioxidant enzyme activity, osmolyte and auxin (IAA) contents, root activity, rhizosphere soil nutrient content, and agronomic traits of Tartary buckwheat initially increased and then decreased with an increase in the concentration of exogenous melatonin application, with the best effects observed at 100 µmol L-1. Compared with the Control treatment, the 100 µmol L-1 treatment decreased the contents of malondialdehyde, superoxide anion free radical, and abscisic acid (ABA) by an average of 28.79%, 27.08%, and 31.64%, respectively. Exogenous melatonin treatment significantly increased the yield of Tartary buckwheat under continuous cropping. Plants treated with 10, 50, 100, and 200 µM respectively had 1.88, 2.01, 2.20, and 1.78 times higher yield than those of the Control treatment. In summary, melatonin treatment, particularly 100 µmol L-1, enhanced the continuous cropping tolerance of Tartary buckwheat by increasing antioxidant capacity and osmotica content, coordinating endogenous ABA and IAA content levels, and delaying senescence, ultimately increasing yield.

Foliar spraying exogenous ABA resists chilling stress on adzuki beans (Vigna angularis).

Adzuki bean, an important legume crop, exhibits poor tolerance to low temperatures. To investigate the effect of exogenous abscisic acid (ABA) on the physiological metabolism and yield resistance of adzuki bean under low-temperature stress, we conducted a potted experiment using Longxiaodou 4 (LXD 4) and Tianjinhong (TJH) as test materials and pre-sprayed with exogenous ABA at flowering stage continuously for 5 days with an average of 12°C and an average of 15°C, respectively. We found that, compared with spraying water, foliar spraying exogenous ABA increased the activities of antioxidants and the content of non-enzymatic antioxidants, effectively inhibited the increase of malondialdehyde (MDA), hydrogen peroxide (H2O2) content, O2-· production rate. Exogenous ABA induced the activation of endogenous protective mechanisms by increasing antioxidant enzymes activities such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), as well as elevated levels of non-enzymatic antioxidants including ascorbic acid (ASA) and glutathione (GSH). Moreover, the yield loss of 5.81%-39.84% caused by chilling stress was alleviated by spraying ABA. In conclusion, foliar spraying exogenous ABA can reduce the negative effects of low-temperature stress on the yield of Adzuki beans, which is essential to ensure stable production of Adzuki beans under low-temperature conditions.

Integrated transcriptome and endogenous hormone analyses reveal the factors affecting the yield of Camellia oleifera.

Camellia oleifera is an important woody oil tree in China, in which the flowers and fruits appear during the same period. The endogenous hormone changes and transcription expression levels in different parts of the flower tissue (sepals, petals, stamens, and pistils), flower buds, leaves, and seeds of Changlin 23 high-yield (H), Changlin low-yield (L), and control (CK) C. oleifera groups were studied. The abscisic acid (ABA) content in the petals and stamens in the L group was significantly higher than that in the H and CK groups, which may be related to flower and fruit drops. The high N6-isopentenyladenine (iP) and indole acetic acid (IAA) contents in the flower buds may be associated with a high yield. Comparative transcriptome analysis showed that the protein phosphatase 2C (PP2C), jasmonate-zim-domain protein (JAZ), and WRKY-related differentially expressed genes (DEGs) may play an important role in determining leaf color. Gene set enrichment analysis (GSEA) comparison showed that jasmonic acid (JA) and cytokinin play an important role in determining the pistil of the H group. In this study, endogenous hormone and transcriptome analyses were carried out to identify the factors influencing the large yield difference in C. oleifera in the same year, which provides a theoretical basis for C. oleifera in the future.

Suppression of SlHDT1 expression increases fruit yield and decreases drought and salt tolerance in tomato.

Histone deacetylation, one of most important types of post-translational modification, plays multiple indispensable roles in plant growth and development and abiotic stress responses. However, little information about the roles of histone deacetylase in regulating inflorescence architecture, fruit yield, and stress responses is available in tomato. Functional characterization revealed that SlHDT1 participated in the control of inflorescence architecture and fruit yield by regulating auxin signalling, and influenced tolerance to drought and salt stresses by governing abscisic acid (ABA) signalling. More inflorescence branches and higher fruit yield, which were influenced by auxin signalling, were observed in SlHDT1-RNAi transgenic plants. Moreover, tolerance to drought and salt stresses was decreased in SlHDT1-RNAi transgenic lines compared with the wild type (WT). Changes in parameters related to the stress response, including decreases in survival rate, chlorophyll content, relative water content (RWC), proline content, catalase (CAT) activity and ABA content and an increase in malonaldehyde (MDA) content, were observed in SlHDT1-RNAi transgenic lines. In addition, the RNA-seq analysis revealed varying degrees of downregulation for genes such as the stress-related genes SlABCC10 and SlGAME6 and the pathogenesis-related protein P450 gene SlCYP71A1, and upregulation of the pathogenesis-related protein P450 genes SlCYP94B1, SlCYP734A7 and SlCYP94A2 in SlHDT1-RNAi transgenic plants, indicating that SlHDT1 plays an important role in the response to biotic and abiotic stresses by mediating stress-related gene expression. In summary, the data suggest that SlHDT1 plays essential roles in the regulation of inflorescence architecture and fruit yield and in the response to drought and salt stresses.

Abscisic acid improves drought resilience, growth, physio-biochemical and quality attributes in wheat (Triticum aestivum L.) at critical growth stages.

Wheat is an important staple crop not only in Pakistan but all over the globe. Although the area dedicated to wheat cultivation expands annually, the quantity of wheat harvested is declining due to various biotic and abiotic factors. Global wheat production and output have suffered as a result of the drought, which is largely driven by a lack of water and environmental factors. Organic fertilizers have been shown to reduce the severity of drought. The current research was conducted in semi-arid climates to mitigate the negative effects of drought on wheat during its critical tillering (DTS), flowering (DFS), and grain filling (DGFS) stages through the application of three different abscisic acid treatments: ABA0 (0 mgL-1) control, ABA1 (100 mgL-1) and ABA2 (200 mgL-1). Wheat growth and yield characteristics were severely harmed by drought stress across all critical development stages, with the DGFS stage being particularly vulnerable and leading to a considerable loss in yield. Plant height was increased by 24.25%, the number of fertile tillers by 25.66%, spike length by 17.24%, the number of spikelets per spike by 16.68%, grain count per spike by 11.98%, thousand-grain weight by 14.34%, grain yield by 26.93% and biological yield by 14.55% when abscisic acid (ABA) was applied instead of the control treatment. Moreover, ABA2 increased the more physiological indices (water use efficiency (36.12%), stomatal conductance (44.23%), chlorophyll a (24.5%), chlorophyll b (29.8%), transpiration rate (23.03%), photosynthetic rate (24.84%), electrolyte leakage (- 38.76%) hydrogen peroxide (- 18.09%) superoxide dismutase (15.3%), catalase (20.8%), peroxidase (- 18.09%), and malondialdehyde (- 13.7%)) of drought-stressed wheat as compared to other treatments. In the case of N, P, and K contents in grain were maximally improved with the application of ABA2. Through the use of principal component analysis, we were able to correlate our results across scales and provide an explanation for the observed effects of ABA on wheat growth and production under arid conditions. Overall, ABA application at a rate of 200 mgL-1 is an effective technique to boost wheat grain output by mitigating the negative effects of drought stress.

Transcriptomic and Hormonal Changes in Wheat Roots Enhance Growth under Moderate Soil Drying.

Understanding the mechanisms that regulate plant root growth under soil drying is an important challenge in root biology. We observed that moderate soil drying promotes wheat root growth. To understand whether metabolic and hormonic changes are involved in this regulation, we performed transcriptome sequencing on wheat roots under well-watered and moderate soil drying conditions. The genes upregulated in wheat roots under soil drying were mainly involved in starch and sucrose metabolism and benzoxazinoid biosynthesis. Various plant hormone-related genes were differentially expressed during soil drying. Quantification of the plant hormones under these conditions showed that the concentrations of abscisic acid (ABA), cis-zeatin (CZ), and indole-3-acetic acid (IAA) significantly increased during soil drying, whereas the concentrations of salicylic (SA), jasmonic (JA), and glycosylated salicylic (SAG) acids significantly decreased. Correlation analysis of total root length and phytohormones indicated that CZ, ABA, and IAA are positively associated with wheat root length. These results suggest that changes in metabolic pathways and plant hormones caused by moderate soil drying help wheat roots grow into deeper soil layers.

Insights from Structure-Based Simulations into the Persulfidation of Uridine Diphosphate-Glycosyltransferase71c5 Facilitating the Reversible Inactivation of Abscisic Acid.

The action of abscisic acid (ABA) is closely related to its level in plant tissues. Uridine diphosphate-glycosyltransferase71c5 (UGT71C5) was characterized as a major UGT enzyme to catalyze the formation of the ABA-glucose ester (ABA-GE), a reversible inactive form of free ABA in Arabidopsis thaliana (thale cress). UGTs function in a mode where the catalytic base deprotonates an acceptor to allow a nucleophilic attack at the anomeric center of the donor, achieving the transfer of a glucose moiety. The proteomic data revealed that UGT71C5 can be persulfidated. Herein, an experimental method was employed to detect the persulfidation site of UGT71C5, and the computational methods were further used to identify the yet unknown molecular basis of ABA glycosylation as well as the regulatory role of persulfidation in this process. Our results suggest that the linker and the U-shaped loop are regulatory structural elements: the linker is associated with the binding of uridine diphosphate glucose (UPG) and the U-shaped loop is involved in binding both UPG and ABA.It was also found that it is through tuning the dynamics of the U-shaped loop that is accompanied by the movement of tyrosine (Y388) that the persulfidation of cysteine (C311) leads to the catalytic residue histidine (H16) being in place, preparing for the deprotonation of ABA, and then reorientates UPG and deprotonated ABA closer to the 'Michaelis' complex, facilitating the transfer of a glucose moiety. Ultimately, the persulfidation of UGT71C5 is in favor of ABA glycosylation. Our results provide insights into the molecular details of UGT71C5 recognizing substrates and insights concerning persulfidation as a possible mechanism for hydrogen sulfide (H2S) to modulate the content of ABA, which helps us understand how modulating ABA level strengthens plant tolerance.

OsMBF1a Facilitates Seed Germination by Regulating Biosynthesis of Gibberellic Acid and Abscisic Acid in Rice.

Seed germination is a pivotal stage in the plant life cycle, orchestrated by a myriad of internal and external factors, notably plant hormones. The underlying molecular mechanisms governing rice seed germination remain largely unelucidated. Herein, we uncover OsMBF1a as a crucial regulatory factor that employs a dual strategy to promote seed germination: positively activating genes involved in gibberellin (GA) biosynthesis pathways, while negatively regulating key genes responsible for abscisic acid (ABA) synthesis. Furthermore, OsMBF1a modulates the endogenous levels of ABA and GA in rice seeds, reinforcing its central role in the germination process. The expression of ZmMBF1a and ZmMBF1b, the homologous genes in maize, in rice seeds similarly affects germination, indicating the conserved functionality of MBF1 family genes in regulating seed germination. This study provides novel insights into the molecular mechanisms underlying rice seed germination and underscores the significance of MBF1 family genes in plant growth and development.

Transcriptomic and coexpression network analyses revealed the regulatory mechanism of Cydia pomonella infestation on the synthesis of phytohormones in walnut husks.

The codling moth (Cydia pomonella) has a major effect on the quality and yield of walnut fruit. Plant defences respond to insect infestation by activating hormonal signalling and the flavonoid biosynthetic pathway. However, little is known about the role of walnut husk hormones and flavonoid biosynthesis in response to C. pomonella infestation. The phytohormone content assay revealed that the contents of salicylic acid (SA), abscisic acid (ABA), jasmonic acid (JA), jasmonic acid-isoleucine conjugate (JA-ILE), jasmonic acid-valine (JA-Val) and methyl jasmonate (MeJA) increased after feeding at different time points (0, 12, 24, 36, 48, and 72 h) of walnut husk. RNA-seq analysis of walnut husks following C. pomonella feeding revealed a temporal pattern in differentially expressed genes (DEGs), with the number increasing from 3,988 at 12 h to 5,929 at 72 h postfeeding compared with the control at 0 h postfeeding. Walnut husks exhibited significant upregulation of genes involved in various defence pathways, including flavonoid biosynthesis (PAL, CYP73A, 4CL, CHS, CHI, F3H, ANS, and LAR), SA (PAL), ABA (ZEP and ABA2), and JA (AOS, AOC, OPR, JAZ, and MYC2) pathways. Three gene coexpression networks that had a significant positive association with these hormonal changes were constructed based on the basis of weighted gene coexpression network analysis (WGCNA). We identified several hub transcription factors, including the turquoise module (AIL6, MYB4, PRE6, WRKY71, WRKY31, ERF003, and WRKY75), the green module (bHLH79, PCL1, APRR5, ABI5, and ILR3), and the magenta module (ERF27, bHLH35, bHLH18, TIFY5A, WRKY31, and MYB44). Taken together, these findings provide useful genetic resources for exploring the defence response mediated by phytohormones in walnut husks.

Nutrient competition between female cones and young seeds in spring affects the physiological dropping and nut-setting rate in Torreya grandis.

Physiological seed drop is a recognized phenomenon in economic forest, caused by the abscission of developing seeds due to intergroup competition for resources. However, little is known about the resource allocation dynamics in species exhibiting a biennial fruiting cycle, where interactions occur not only among seeds of the same year but also between reproductive structures from consecutive years. In this study, we explored the dynamics of resource allocation in Torreya grandis, a nut crop with a prototypical two-year seed development pattern. We implemented thinning treatments of 0%, 30%, and 60% on female cones and/or immature seeds during the spring, targeting various stages of development both pre- and post-pollination. Our findings reveal a pronounced resource competition in Torreya, evidenced by a natural seed-setting rate of merely 9.4%. Contrary to expectations, seed thinning did not lead to an obvious increase in nut-setting rates, whereas a substantial increase to 20.5% was observed when female cones were thinned by 60% at 20 days before pollination. The cone thinning treatment appears to have influenced seed development through positive cytokinin and negative abscisic acid effects. This indicates that intergroup competition between female cones and nuts is a more significant factor in seed drop than inner nut competition, and there seems to be an interaction between the two groups. We demonstrate that, in Torreya with biennial seed development, it is the competition between female cones and immature seeds that is important. This insight expands our comprehension of the physiological mechanisms governing seed drop in biennial fruiting species and managing the reproductive organ load to optimize nutrient allocation.