Wheat TaTIFY3B and TaTIFY10A play roles in seed germination and abiotic stress responses in transgenic Arabidopsis and rice.

BACKGROUND: Seed germination is a key process in the plant life cycle that affects the vegetative and reproductive stages of plants. Although the JAZ gene family has been characterized in many plants, the relationship between the JAZ gene and seed germination is still unclear. RESULTS: We identified two members of the JAZ family from wheat, TaTIFY3B and TaTIFY10A. TaTIFY3B and TaTIFY10A were localized in both the cell membrane and nucleus. Spatio-temporal expression analysis of TaTIFY3B and TaTIFY10A in wheat revealed that these genes are essential for the preharvest sprouting (PHS) stage of seed development, with expression levels significantly decreasing during the ripening period. Transgenic rice plants overexpressing wheat TaTIFY3B and TaTIFY10A improved seed germination rates. Transgenic Arabidopsis plants overexpressing wheat TaTIFY10A improved seed germination rates and promoted flowering. In addition, abscisic acid (ABA) and jasmonic acid (JA) were found to induce TaTIFY3B and TaTIFY10A expression. Under different ABA concentrations, the seed germination rates of transgenic rice and Arabidopsis overexpressing TaTIFY3B and TaTIFY10A are superior to wild-type (WT) and mutant plants, and the root lengths of Arabidopsis overexpressing TaTIFY3B and TaTIFY10A also change. Under different JA concentrations, there is no difference in the seed germination rate of rice overexpressing TaTIFY3B and TaTIFY10A compared to WT and mutant plants, but there is a significant difference in the seed germination rate and root length of overexpressing Arabidopsis compared to WT and mutant plants. Under different concentrations of salt and drought treatments, the seed germination rate and root length of overexpressing Arabidopsis of TaTIFY3B and TaTIFY10A are affected. CONCLUSIONS: This study offers a novel perspective for understanding the molecular basis of pre-harvest sprouting and provides potential candidate genes for controlling wheat seed germination.

Genome-wide identification and expression analysis of two-component system genes in switchgrass (Panicum virgatum L.).

The two-component system (TCS) consists of histidine kinase (HK), histidine phosphate transfer protein (HP), and response regulatory factor (RR). It is one of the most crucial components of signal transduction in plants, playing a significant role in regulating plant growth, development, and responses to various abiotic stresses. Although TCS genes have been extensively identified in a variety of plants, the genome-wide recognition and examination of TCS in switchgrass remain unreported. Accordingly, this study identified a total of 87 TCS members in the genome of switchgrass, comprising 20 HK(L)s, 10 HPs, and 57 RRs. Detailed analyses were also conducted on their gene structures, conserved domains, and phylogenetic relationships. Moreover, this study analysed the gene expression profiles across diverse organs and investigated their response patterns to adverse environmental stresses. Results revealed that 87 TCS genes were distributed across 18 chromosomes, with uneven distribution. Expansion of these genes in switchgrass was achieved through both fragment and tandem duplication. PvTCS members are relatively conservative in the evolutionary process, but the gene structure varies significantly. Various cis-acting elements, varying in types and amounts, are present in the promoter region of PvTCSs, all related to plant growth, development, and abiotic stress, due to the TCS gene structure. Protein-protein interaction and microRNA prediction suggest complex interactions and transcriptional regulation among TCS members. Additionally, most TCS members are expressed in roots and stems, with some genes showing organ-specific expression at different stages of leaf and inflorescence development. Under conditions of abiotic stress such as drought, low temperature, high temperature, and salt stress, as well as exogenous abscisic acid (ABA), the expression of most TCS genes is either stimulated or inhibited. Our systematic analysis could offer insight into the characterization of the TCS genes, and further the growth of functional studies in switchgrass.

Genome-wide analysis of the switchgrass YABBY family and functional characterization of PvYABBY14 in response to ABA and GA stress in Arabidopsis.

BACKGROUND: The small YABBY plant-specific transcription factor has a prominent role in regulating plant growth progress and responding to abiotic stress. RESULTS: Here, a total of 16 PvYABBYs from switchgrass (Panicum virgatum L.) were identified and classified into four distinct subgroups. Proteins within the same subgroup exhibited similar conserved motifs and gene structures. Synteny analyses indicated that segmental duplication contributed to the expansion of the YABBY gene family in switchgrass and that complex duplication events occurred in rice, maize, soybean, and sorghum. Promoter regions of PvYABBY genes contained numerous cis-elements related to stress responsiveness and plant hormones. Expression profile analysis indicated higher expression levels of many PvYABBY genes during inflorescence development and seed maturation, with lower expression levels during root growth. Real-time quantitative PCR analysis demonstrated the sensitivity of multiple YABBY genes to PEG, NaCl, ABA, and GA treatments. The overexpression of PvYABBY14 in Arabidopsis resulted in increased root length after treatment with GA and ABA compared to wild-type plants. CONCLUSIONS: Taken together, our study provides the first genome-wide overview of the YABBY transcription factor family, laying the groundwork for understanding the molecular basis and regulatory mechanisms of PvYABBY14 in response to ABA and GA responses in switchgrass.

Large-scale identification of novel transcriptional regulators of the aliphatic glucosinolate pathway in Arabidopsis.

Aliphatic glucosinolates are a large group of plant secondary metabolites characteristic of Brassicaceae, including the model plant Arabidopsis. The diverse and complex degradation products of aliphatic glucosinolates contribute to plant responses to herbivory, pathogen attack, and environmental stresses. Most of the biosynthesis genes in the aliphatic glucosinolate pathway have been cloned in Arabidopsis, and the research focus has recently shifted to the regulatory mechanisms controlling aliphatic glucosinolate accumulation. Up till now, more than 40 transcriptional regulators have been identified as regulating the aliphatic glucosinolate pathway, but many more novel regulators likely remain to be discovered based on research evidence over the past decade. In the current study, we took a systemic approach to functionally test 155 candidate transcription factors in Arabidopsis identified by yeast one-hybrid assay, and successfully validated at least 30 novel regulators that could significantly influence the accumulation of aliphatic glucosinolates in our experimental set-up. We also showed that the regulators of the aliphatic glucosinolate pathway have balanced positive and negative effects, and glucosinolate metabolism and plant development can be coordinated. Our work is the largest scale effort so far to validate transcriptional regulators of a plant secondary metabolism pathway, and provides new insights into how the highly diverse plant secondary metabolism is regulated at the transcriptional level.

Analysis of morphological traits and regulatory mechanism of a semi-dwarf, albino, and blue grain wheat line.

The plant height and leaf color are important traits in crops since they contribute to the production of grains and biomass. Progress has been made in mapping the genes that regulate plant height and leaf color in wheat (Triticum aestivum L.) and other crops. Wheat line DW-B (dwarfing, white leaves, and blue grains) with semi-dwarfing and albinism at the tillering stage and re-greening at the jointing stage was created using Lango and Indian Blue Grain. Transcriptomic analyses of the three wheat lines at the early jointing stages indicated that the genes of gibberellin (GA) signaling pathway and chlorophyll (Chl) biosynthesis were expressed differently in DW-B and its parents. Furthermore, the response to GA and Chl contents differed between DW-B and its parents. The dwarfing and albinism in DW-B were owing to defects in the GA signaling pathway and abnormal chloroplast development. This study can improve understanding of the regulation of plant height and leaf color. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-023-01379-z.

Study on association of serum uric acid levels with bipolar disorder: systematic review and meta-analysis in Chinese patients.

BACKGROUND: The purine system represented by uric acid may be involved in the pathogenesis of bipolar disorder, This study intends to explore the association of serum uric acid levels with bipolar disorder in Chinese patients through meta-analysis. METHODS: Electronic databases, including PubMed, Embase, Web of Science, and China National Knowledge Infrastructure (CNKI), searching from inception to December 2022. Randomized Controlled Trials that reported serum uric acid levels and bipolar disorder were included. Two investigators independently extracted data and RevMan5.4 and Stata14.2 were used for statistical analyses. RESULTS: Twenty-eight studies with 4482 bipolar disorder, 1568 depression, 785 schizophrenia, and 2876 healthy control subjects were included in this meta-analysis. The results of the meta-analysis showed that serum uric acid levels in the bipolar disorder group were significantly higher than those in depression [SMD 0.53 (0.37, 0.70), p < 0.00001], schizophrenia [SMD 0.27 (0.05, 0.49), p = 0.02] and healthy control group [SMD 0.87 (0.67, 1.06), p < 0.00001]. Subgroup-analysis showed that in Chinese people with bipolar disorder, uric acid levels of the manic episode were higher than the depressed episode [SMD 0.31 (0.22, 0.41), p < 0.00001]. CONCLUSION: Our results indicated a strong association between serum uric acid levels and bipolar disorder in Chinese patients, but further studies about whether uric acid levels can be a biomarker for bipolar disorder still need to investigate.

Effect of Mowing on Wheat Growth at Seeding Stage.

Winter wheat is used as forage at the tillering stage in many countries; however, the regrowth pattern of wheat after mowing remains unclear. In this study, the growth patterns of wheat were revealed through cytological and physiological assessments as well as transcriptome sequencing. The results of agronomic traits and paraffin sections showed that the shoot growth rate increased, but root growth was inhibited after mowing. The submicroscopic structure revealed a decrease in heterochromatin in the tillering node cell and a change in mitochondrial shape in the tillering node and secondary root. Analysis of the transcriptome showed the number of differentially expressed genes (DEGs) involved in biological processes, cellular components, and molecular functions; 2492 upregulated DEGs and 1534 downregulated DEGs were identified. The results of the experimental study showed that mowing induced expression of DEGs in the phenylpropanoid biosynthesis pathway and increased the activity of PAL and 4CL. The upregulated DEGs in the starch and sucrose metabolism pathways and related enzyme activity alterations indicated that the sugar degradation rate increased. The DEGs in the nitrogen metabolism pathway biosynthesis of the amino acids, phenylpropanoid biosynthesis metabolism, and in the TCA pathway also changed after mowing. Hormone content and related gene expression was also altered in the tillering and secondary roots after mowing. When jasmonic acid and ethylene were used to treat the wheat after mowing, the regeneration rate increased, whereas abscisic acid inhibited regrowth. This study revealed the wheat growth patterns after mowing, which could lead to a better understanding of the development of dual-purpose wheat.

Rapid and Nondestructive Evaluation of Wheat Chlorophyll under Drought Stress Using Hyperspectral Imaging.

Chlorophyll drives plant photosynthesis. Under stress conditions, leaf chlorophyll content changes dramatically, which could provide insight into plant photosynthesis and drought resistance. Compared to traditional methods of evaluating chlorophyll content, hyperspectral imaging is more efficient and accurate and benefits from being a nondestructive technique. However, the relationships between chlorophyll content and hyperspectral characteristics of wheat leaves with wide genetic diversity and different treatments have rarely been reported. In this study, using 335 wheat varieties, we analyzed the hyperspectral characteristics of flag leaves and the relationships thereof with SPAD values at the grain-filling stage under control and drought stress. The hyperspectral information of wheat flag leaves significantly differed between control and drought stress conditions in the 550-700 nm region. Hyperspectral reflectance at 549 nm (r = -0.64) and the first derivative at 735 nm (r = 0.68) exhibited the strongest correlations with SPAD values. Hyperspectral reflectance at 536, 596, and 674 nm, and the first derivatives bands at 756 and 778 nm, were useful for estimating SPAD values. The combination of spectrum and image characteristics (L*, a*, and b*) can improve the estimation accuracy of SPAD values (optimal performance of RFR, relative error, 7.35%; root mean square error, 4.439; R2, 0.61). The models established in this study are efficient for evaluating chlorophyll content and provide insight into photosynthesis and drought resistance. This study can provide a reference for high-throughput phenotypic analysis and genetic breeding of wheat and other crops.

Comprehensive Transcriptomic and Metabolic Profiling of Agrobacterium-tumefaciens-Infected Immature Wheat Embryos.

The transformation efficiency (TE) was improved by a series of special chemical and physical methods using immature embryos from the cultivar Fielder, with the PureWheat technique. To analyze the reaction of immature embryos infected, which seemed to provide the necessary by Agrobacterium tumefaciens in PureWheat, a combination of scanning electron microscopy (SEM), complete transcriptome analysis, and metabolome analysis was conducted to understand the progress. The results of the SEM analysis revealed that Agrobacterium tumefaciens were deposited under the damaged cortex of immature embryos as a result of pretreatment and contacted the receptor cells to improve the TE. Transcriptome analysis indicated that the differentially expressed genes were mainly enriched in phenylpropanoid biosynthesis, starch and sucrose metabolism, plant-pathogen interaction, plant hormone signal transduction, and the MAPK (Mitogen-activated protein kinase) signaling pathway. By analyzing the correlation between differentially expressed genes and metabolites, the expression of many genes and the accumulation of metabolites were changed in glucose metabolism and the TCA cycle (Citrate cycle), as well as the amino acid metabolism; this suggests that the infection of wheat embryos with Agrobacterium is an energy-demanding process. The shikimate pathway may act as a hub between glucose metabolism and phenylpropanoid metabolism during Agrobacterium infection. The downregulation of the F5H gene and upregulation of the CCR gene led to the accumulation of lignin precursors through phenylpropanoid metabolism. In addition, several metabolic pathways and oxidases were found to be involved in the infection treatment, including melatonin biosynthesis, benzoxazinoid biosynthesis, betaine biosynthesis, superoxide dismutase, and peroxidase, suggesting that wheat embryos may be under the stress of Agrobacterium and, thus, undergo an oxidative stress response. These findings explore the physiological and molecular changes of immature embryos during the co-culture stage of the PureWheat technique and provide insights for Agrobacterium-mediated transgenic wheat experiments.

A Systematic Review and Meta-Analysis of Metabolic Syndrome Prevalence in Chinese Inpatients with Bipolar Disorder.

The aim of the work was to study the prevalence of metabolic syndrome in Chinese patients with bipolar disorder. We searched Chinese literature related to the study in prevalence of metabolic syndrome in bipolar disorder in Chinese language, among which results such as comments, letters, reviews and case reports were excluded. The prevalence of metabolic syndrome in bipolar disorder was researched and discussed. A total of 1562 subjects were included in 11 studies. The prevalence of MetS in bipolar disorder was 33% (95% CI=0.29-0.37), which was higher significantly than normal control (10.82%), but similar to schizophrenia (31.59%). The 41.41% prevalence of MetS in male patients was higher significantly than that in females (26.83%).The prevalence of MetS in BD treated by AAP was 47.54%, by MS was 19.19%, by MS+AAP was 40%.The prevalence of MetS in BD treated by carbamazepine was 28.21%, by lithium was 30%, by valproate was 21.71%, by clozepine was 51.43%, by olanzapine was 39.84%, by quetiapine was 39.44%, and by risperidone was 35%. The prevalence of MetS in bipolar disorder was 33% (95% CI=0.29-0.37), which was higher significantly than normal control (10.82%), but similar to schizophrenia (31.59%). AAP and MS were the main one risks of MetS in BD.

Genome-Wide Identification of Wheat KNOX Gene Family and Functional Characterization of TaKNOX14-D in Plants.

The KNOX genes play important roles in maintaining SAM and regulating the development of plant leaves. However, the TaKNOX genes in wheat are still not well understood, especially their role in abiotic stress. In this study, a total of 36 KNOX genes were identified, and we demonstrated the function of the TaKNOX14-D gene under mechanical injury and cold stress. Thirty-six TaKNOX genes were divided into two groups, and thirty-four TaKNOX genes were predicted to be located in the nucleus by Cell-PLoc. These genes contained five tandem duplications. Fifteen collinear gene pairs were exhibited in wheat and rice, one collinear gene pair was exhibited in wheat and Arabidopsis. The phylogenetic tree and motif analysis suggested that the TaKNOX gene appeared before C3 and C4 diverged. Gene structure showed that the numbers of exons and introns in TaKNOX gene are different. Wheat TaKNOX genes showed different expression patterns during the wheat growth phase, with seven TaKNOX genes being highly expressed in the whole growth period. These seven genes were also highly expressed in most tissues, and also responded to most abiotic stress. Eleven TaKNOX genes were up-regulated in the tillering node during the leaf regeneration period after mechanical damage. When treating the wheat with different hormones, the expression patterns of TaKNOX were changed, and results showed that ABA promoted TaKNOX expression and seven TaKNOX genes were up-regulated under cytokinin and auxin treatment. Overexpression of the TaKNOX14-D gene in Arabidopsis could increase the leaf size, plant height and seed size. This gene overexpression in Arabidopsis also increased the compensatory growth capacity after mechanical damage. Overexpression lines also showed high resistance to cold stress. This study provides a better understanding of the TaKNOX genes.

Phosphorylation of MtRopGEF2 by LYK3 mediates MtROP activity to regulate rhizobial infection in Medicago truncatula.

The formation of nitrogen-fixing no dules on legume roots requires the coordination of infection by rhizobia at the root epidermis with the initiation of cell divisions in the root cortex. During infection, rhizobia attach to the tip of elongating root hairs which then curl to entrap the rhizobia. However, the mechanism of root hair deformation and curling in response to symbiotic signals is still elusive. Here, we found that small GTPases (MtRac1/MtROP9 and its homologs) are required for root hair development and rhizobial infection in Medicago truncatula. Our results show that the Nod factor receptor LYK3 phosphorylates the guanine nucleotide exchange factor MtRopGEF2 at S73 which is critical for the polar growth of root hairs. In turn, phosphorylated MtRopGEF2 can activate MtRac1. Activated MtRac1 was found to localize at the tips of root hairs and to strongly interact with LYK3 and NFP. Taken together, our results support the hypothesis that MtRac1, LYK3, and NFP form a polarly localized receptor complex that regulates root hair deformation during rhizobial infection.

Genome-wide analysis of the abiotic stress-related bZIP family in switchgrass.

The large basic leucine zipper (bZIP) transcription factor family is conserved in plants. These proteins regulate growth, development, and stress response. Here, we conducted a genome-wide analysis to identify the bZIP genes associated with stress resistance in switchgrass (Panicum virgatum L.). We identified 178 PvbZIPs unevenly distributed on 18 switchgrass chromosomes. An evolutionary analysis segregated them into 10 subfamilies. Gene structure and conserved motif analyses indicated that the same subfamily members shared similar intron-exon modes and motif compositions. This finding corroborated the proposed PvbZIP family grouping. A promoter analysis showed that PvbZIP genes participate in various stress responses. Phylogenetic and synteny analyses characterized 111 switchgrass bZIPs as orthologs of 70 rice bZIPs. A protein interaction network analysis revealed that 22 proteins are involved in salt and drought tolerance. An expression atlas disclosed that the expression patterns of several PvbZIPs differ among various tissues and developmental stages. Online data demonstrated that 16 PvbZIPs were significantly downregulated and five were significantly upregulated in response to heat stress. Other PvbZIPs participated in responses to abiotic stress such as salt, drought, cold, and heat. Our genome-wide analysis and identification of the switchgrass bZIP family characterized multiple candidate PvbZIPs that regulate growth and stress response. This study lays theoretical and empirical foundations for future functional investigations into other transcription factors.

Proteomic analysis of the similarities and differences of soil drought and polyethylene glycol stress responses in wheat (Triticum aestivum L.).

KEY MESSAGE: Our results reveal both soil drought and PEG can enhance malate, glutathione and ascorbate metabolism, and proline biosynthesis, whereas soil drought induced these metabolic pathways to a greater degree than PEG. Polyethylene glycol (PEG) is widely used to simulate osmotic stress, but little is known about the different responses of wheat to PEG stress and soil drought. In this study, isobaric tags for relative quantification (iTRAQ)-based proteomic techniques were used to determine both the proteomic and physiological responses of wheat seedlings to soil drought and PEG. The results showed that photosynthetic rate, stomatal conductance, intercellular CO2 concentration, transpiration rate, maximum potential efficiency of PS II, leaf water content, relative electrolyte leakage, MDA content, and free proline content exhibited similar responses to soil drought and PEG. Approximately 15.8% of differential proteins were induced both by soil drought and PEG. Moreover, both soil drought and PEG inhibited carbon metabolism and the biosynthesis of some amino acids by altering the accumulation of glyceraldehyde-3-phosphate dehydrogenase, ribulose-bisphosphate carboxylase, and phosphoglycerate kinase, but they both enhanced the metabolism of malate, proline, glutathione, and ascorbate by increasing the accumulation of key enzymes including malate dehydrogenase, monodehydroascorbate reductase, pyrroline-5-carboxylate dehydrogenase, pyrroline-5-carboxylate synthetase, ascorbate peroxidase, glutathione peroxidase, and glutathione S-transferase. Notably, the latter five of these enzymes were found to be more sensitive to soil drought. In addition, polyamine biosynthesis was specifically induced by increased gene expression and protein accumulation of polyamine oxidase and spermidine synthase under PEG stress, whereas fructose-bisphosphate aldolase and arginase were induced by soil drought. Therefore, present results suggest that PEG is an effective method to simulate drought stress, but the key proteins related to the metabolism of malate, glutathione, ascorbate, proline, and polyamine need to be confirmed under soil drought.

Long non-coding RNAs of switchgrass (Panicum virgatum L.) in multiple dehydration stresses.

BACKGROUND: Long non-coding RNAs (lncRNAs) play important roles in plant growth and stress responses. Studies of lncRNAs in non-model plants are quite limited, especially those investigating multiple dehydration stresses. In this study, we identified novel lncRNAs and analyzed their functions in dehydration stress memory in switchgrass, an excellent biofuel feedstock and soil-conserving plant in the Gramineae family. RESULTS: We analyzed genome-wide transcriptional profiles of leaves of 5-week-old switchgrass plantlets grown via tissue culture after primary and secondary dehydration stresses (D1 and D2) and identified 16,551 novel lncRNAs, including 4554 annotated lncRNAs (targeting 3574 genes), and 11,997 unknown lncRNAs. Gene ontology and pathway enrichment analysis of annotated genes showed that the differentially expressed lncRNAs were related to abscisic acid (ABA) and ethylene (ETH) biosynthesis and signal transduction, and to starch and sucrose metabolism. The upregulated lncRNAs and genes were related to ABA synthesis and its signal transduction, and to trehalose synthesis. Meanwhile, lncRNAs and genes related to ETH biosynthesis and signal transduction were suppressed. LncRNAs and genes involved in ABA metabolism were verified using quantitative real-time PCR, and the endogenous ABA content was determined via high performance liquid chromatography mass spectrometry (HPLC-MS). These results showed that ABA accumulated significantly during dehydration stress, especially in D2. Furthermore, we identified 307 dehydration stress memory lncRNAs, and the ratios of different memory types in switchgrass were similar to those in Arabidopsis and maize. CONCLUSIONS: The molecular responses of switchgrass lncRNAs to multiple dehydration stresses were researched systematically, revealing novel information about their transcriptional regulatory behavior. This study provides new insights into the response mechanism to dehydration stress in plants. The lncRNAs and pathways identified in this study provide valuable information for genetic modification of switchgrass and other crops.

Two virulent sRNAs identified by genomic sequencing target the type III secretion system in rice bacterial blight pathogen.

BACKGROUND: Small non-coding RNA (sRNA) short sequences regulate various biological processes in all organisms, including bacteria that are animal or plant pathogens. Virulent or pathogenicity-associated sRNAs have been increasingly elucidated in animal pathogens but little is known about similar category of sRNAs in plant-pathogenic bacteria. This is particularly true regarding rice bacterial blight pathogen Xanthomonas oryzae pathovar oryzae (Xoo) as studies on the virulent role of Xoo sRNAs is very limited at present. RESULTS: The number and genomic distribution of sRNAs in Xoo were determined by bioinformatics analysis based on high throughput sequencing (sRNA-Seq) of the bacterial cultures from virulence-inducing and standard growth media, respectively. A total of 601 sRNAs were identified in the Xoo genome and ten virulent sRNA candidates were screened out based on significant differences of their expression levels between the culture conditions. In addition, trans3287 and trans3288 were also selected as candidates due to high expression levels in both media. The differential expression of 12 sRNAs evidenced by the sRNA-Seq data was confirmed by a convincing quantitative method. Based on genetic analysis of Xoo ΔsRNA mutants generated by deletion of the 12 single sRNAs, trans217 and trans3287 were characterized as virulent sRNAs. They are essential not only for the formation of bacterial blight in a susceptible rice variety Nipponbare but also for the induction of hypersensitive response (HR) in nonhost plant tobacco. Xoo Δtrans217 and Δtrans3287 mutants fail to induce bacterial blight in Nipponbare and also fail to induce the HR in tobacco, whereas, genetic complementation restores both mutants to the wild type in the virulent performance and HR induction. Similar effects of gene knockout and complementation were found in the expression of hrpG and hrpX genes, which encode regulatory proteins of the type III secretion system. Consistently, secretion of a type III effector, PthXo1, is blocked in Δtrans217 or Δtrans3287 bacterial cultures but retrieved by genetic complementation to both mutants. CONCLUSIONS: The genetic analysis characterizes trans217 and trans3287 as pathogenicity-associated sRNAs essential for the bacterial virulence on the susceptible rice variety and for the HR elicitation in the nonhost plant. The molecular evidence suggests that both virulent sRNAs regulate the bacterial virulence by targeting the type III secretion system.

Proteomic analysis of melatonin-mediated osmotic tolerance by improving energy metabolism and autophagy in wheat (Triticum aestivum L.).

MAIN CONCLUSION: Melatonin-mediated osmotic tolerance was attributed to increased antioxidant capacity, energy metabolism, osmoregulation and autophagy in wheat (Triticum aestivum L.). Melatonin is known to play multiple roles in plant abiotic stress tolerance. However, its role in wheat has been rarely investigated. In this study, 25% polyethylene glycol 6000 (PEG 6000) was used to simulate osmotic stress, and wheat seeds and seedlings were treated with different concentrations of melatonin under PEG stress. Isobaric tag for relative and absolute quantification (iTRAQ)-based proteomic techniques were used to identify the differentially accumulated proteins from melatonin-treated and non-treated seedlings. Seeding priming with melatonin significantly increased the germination rate, coleoptile length, and primary root number of wheat under PEG stress, as well as the fresh weight, dry weight, and water content of wheat seedlings. Under PEG stress, melatonin significantly improved reactive oxygen species homeostasis, as revealed by lower H2O2 and O 2· content; and the expression of antioxidant enzymes at the transcription and translation levels was increased. Melatonin maintained seedling growth by improving photosynthetic rates and instantaneous and intrinsic water use efficiencies, as well as carbon fixation and starch synthesis at the protein level. Melatonin treatment significantly affected the expression of glycolytic proteins, including fructose-1,6-bisphosphate aldolase, hexokinase, glyceraldehyde-3-phosphate dehydrogenase, and enolase, and remarkably increased the expression of the nicotinamide adenine dinucleotide transporter and nicotinamide adenine dinucleotide binding protein, thereby indirectly modulating electron transport in the respiratory chain. This indicated that melatonin improved energy production in PEG-stressed seedlings. Further, melatonin played a regulatory role in autophagy, protease expression, and ubiquitin-mediated protein degradation by significantly upregulating rab-related protein, fused signal recognition particle receptor, aspartyl protease, serine protease, ubiquitin-fold modifier 1, and ubiquitin at the mRNA or protein level. These findings suggested that melatonin might activate a metabolic cascade related to autophagy under PEG stress in wheat seedlings.

The PIN1 family gene PvPIN1 is involved in auxin-dependent root emergence and tillering in switchgrass.

Switchgrass (Panicum virgatum L.; family Poaceae) is a warm-season C4 perennial grass. Tillering plays an important role in determining the morphology of aboveground parts and the final biomass yield of switchgrass. Auxin distribution in plants can affect a variety of important growth and developmental processes, including the regulation of shoot and root branching, plant resistance and biological yield. Auxin transport and gradients in plants are mediated by influx and efflux carriers. PvPIN1, a switchgrass PIN1-like gene that is involved in regulating polar transport, is a putative auxin efflux carrier. Neighbor-joining analysis using sequences deposited in NCBI databases showed that the PvPIN1gene belongs to the PIN1 family and is evolutionarily closer to the Oryza sativa japonica group. Tiller emergence and development was significantly promoted in plants subjected toPvPIN1 RNA interference (RNAi), which yielded a phenotype similar to that of wild-type plants treated with the auxin transport inhibitor TIBA (2,3,5-triiodobenzoic acid). A transgenic approach that inducedPvPIN1 gene overexpression or suppression altered tiller number and the shoot/root ratio. These data suggest that PvPIN1plays an important role in auxin-dependent adventitious root emergence and tillering.

The overexpression of the switchgrass (Panicum virgatum L.) genes PvTOC1-N or PvLHY-K affects circadian rhythm and hormone metabolism in transgenic Arabidopsis seedlings.

Switchgrass (Panicum virgatum L.) is a perennial C4 warm-season grass known for its high-biomass yield and wide environmental adaptability, making it an ideal bioenergy crop. Despite its potential, switchgrass seedlings grow slowly, often losing out to weeds in field conditions and producing limited biomass in the first year of planting. Furthermore, during the reproductive growth stage, the above-ground biomass rapidly increases in lignin content, creating a significant saccharification barrier. Previous studies have identified rhythm-related genes TOC1 and LHY as crucial to the slow seedling development in switchgrass, yet the precise regulatory functions of these genes remain largely unexplored. In this study, the genes TOC1 and LHY were characterized within the tetraploid genome of switchgrass. Gene expression analysis revealed that PvTOC1 and PvLHY exhibit circadian patterns under normal growth conditions, with opposing expression levels over time. PvTOC1 genes were predominantly expressed in florets, vascular bundles, and seeds, while PvLHY genes showed higher expression in stems, leaf sheaths, and nodes. Overexpression of PvTOC1 from the N chromosome group (PvTOC1-N) or PvLHY from the K chromosome group (PvLHY-K) in Arabidopsis thaliana led to alterations in circadian rhythm and hormone metabolism, resulting in shorter roots, delayed flowering, and decreased resistance to oxidative stress. These transgenic lines exhibited reduced sensitivity to hormones and hormone inhibitors, and displayed altered gene expression in the biosynthesis and signal transduction pathways of abscisic acid (ABA), gibberellin (GA), 3-indoleacetic acid (IAA), and strigolactone (SL). These findings highlight roles of PvTOC1-N and PvLHY-K in plant development and offer a theoretical foundation for genetic improvements in switchgrass and other crops.

Genome-wide identification, classification, and expression analysis of heat shock transcription factor family in switchgrass (Panicum virgatum L.).

Switchgrass is one of the most promising bioenergy crops and is generally cultivated in arid climates and poor soils. Heat shock transcription factors (Hsfs) are key regulators of plant responses to abiotic and biotic stressors. However, their role and mechanism of action in switchgrass have not been elucidated. Hence, this study aimed to identify the Hsf family in switchgrass and understand its functional role in heat stress signal transduction and heat tolerance by using bioinformatics and RT-PCR analysis. Forty-eight PvHsfs were identified and divided into three main classes based on their gene structure and phylogenetic relationships: HsfA, HsfB, and HsfC. The results of the bioinformatics analysis showed a DNA-binding domain (DBD) at the N-terminal in PvHsfs, and they were not evenly distributed on all chromosomes except for chromosomes 8 N and 8 K. Many cis-elements related to plant development, stress responses, and plant hormones were identified in the promoter sequence of each PvHsf. Segmental duplication is the primary force underlying Hsf family expansion in switchgrass. The results of the expression pattern of PvHsfs in response to heat stress showed that PvHsf03 and PvHsf25 might play critical roles in the early and late stages of switchgrass response to heat stress, respectively, and HsfB mainly showed a negative response to heat stress. Ectopic expression of PvHsf03 in Arabidopsis significantly increased the heat resistance of seedlings. Overall, our research lays a notable foundation for studying the regulatory network in response to deleterious environments and for further excavating tolerance genes in switchgrass.