Plant Abiotic Stress Responses Research Articles

Genome-wide analysis of the AP2/ERF gene family in Tritipyrum and the response of TtERF_B2-50 in salt-tolerance

The AP2/ERF transcription factor is widely distributed across the plant kingdom and plays a crucial role in various abiotic stress responses in plants. Tritipyrum, an octoploid resulting from an intergeneric cross between Triticum aestivum (AABBDD) and Thinopyrum elongatum (EE), is a valuable source of germplasm for incorporating superior traits of Th. elongatum into T. aestivum. With the recent availability of whole -genome sequences for T. aestivum and Th. elongatum, we explored the organization and expression profiling of Tritipyrum AP2/ERF genes across the entire genome. Our investigation identified 543 Tritipyrum AP2/ERF genes, which evolutionary analysis categorized into four major groups (AP2, DREB, ERF, and RAV), whose members share a conserved motif composition. These 543 TtAP2/ERF genes were distributed throughout 28 chromosomes, with 132 duplications. Synteny analysis suggests that the AP2/ERF gene family may have a common ancestor. Transcriptome data and Real-Time PCR expression profiles revealed 43 TtAP2/ERF genes with high expression levels in response to various salt stressors and recovery regimens. Tel2E01T236300 (TtERF_B2-50) was particularly salt stress-sensitive and evolutionarily related to the salt-tolerant gene AtERF7 in A. thaliana. Pearson correlation analysis identified 689 genes positively correlated (R > 0.9) with TtERF_B2-50 expression, enriched in metabolic activities, cellular processes, stimulus response, and biological regulation. Real-time PCR showed that TtERF_B2-50 was highly expressed in roots, stems, and leaves under salt stress. These findings suggest that TtERF_B2-50 may be associated with salt stress tolerance and may serve as a valuable foreign gene for enhancing salt tolerance in wheat.

Tuning the output of the higher plants Circadian Clock

The circadian clock is an ascribed regulator found in the cells of creatures, that keeps biological and behavioral processes in sync with daily environmental changes throughout two 24-hour cycles. When the circadian clock in humans malfunctions or is misaligned with environmental signals, the timing of the sleep-wake cycle is altered and several circadian rhythm sleep disorders result. Due to the Earth's rotation on its axis, predictable environmental changes are anticipated by complex processes. The combined term for these systems is the circadian clock. The circadian rhythm regulates photosynthesis, photoperiodism, and photoperiodism, making it the "primary controller of plant life." The circadian clock is made up of post-translational alterations to core oscillators, epigenetic tweaks to DNA and histones, and autoregulatory feedback loops in transcription. In addition, the circadian clock is cell-autonomous and regulates the circadian rhythms of distinct organs. Biochemical elements such as photosynthetic products, mineral nutrients, calcium ions, and hormones are used by the core oscillators to communicate with one another. Arabidopsis is utilized to identify clock-related genes that govern plant growth, germination, pollination, flowering, abiotic and biotic stress responses, and more. The biological cycles of all species, notably humans, are undoubtedly impacted by other elements, including high altitude and changing ecosystems, in addition to the ones already stated. Although it hasn't yet published any experimental or scientific evidence to support them, the implication that living things have lives does appear inescapable. Hence, the present study elaborates on the higher plants related to the circadian clock.

Genome-wide identification of flowering Chinese cabbage BPC family genes and BcBPC9 functional analysis in Cd stress tolerance

Flowering Chinese cabbage is an important vegetable crop widely cultivated in southern China. However, flowering Chinese cabbage plants are susceptible to diverse environmental influences that mainly affect crop quality and production. The BASIC PENTACYSTEINE (BPC) transcription factor is an essential regulator of plant development and abiotic stress responses. However, the function and molecular mechanism of the BPC family genes in flowering Chinese cabbage remain unclear. This study aimed to investigate the molecular mechanisms of the BcBPC gene in abiotic stress tolerance. In flowering Chinese cabbage, 12 BcBPC family genes have been identified and found to be unequally distributed on eight chromosomes. Comprehensive analyses of BcBPC gene structure, motif analysis, cis-regulatory elements, and subcellular localization were performed. BcBPC genes were classified into three groups based on their sequence composition, phylogenetic relationships, and conserved domains, which were highly linked to those of other species. BcBPC family gene promoter consists 69.92% stress-responsive, 32.38% hormone-responsive, and 5.30%, related to growth- and biological process-responsive cis-regulatory elements. Subsequent qRT-PCR results showed that BcBPC genes were highly upregulated under abiotic stress, especially under NaCl and Cd stress. The overexpression of BcBPC9 increases Cd stress tolerance in yeast. BcBPC9 is located in the nucleus, but moves to the cell wall when exposed to Cd stress. BcBPC9 transient overexpression tobacco were improved growth and upregulated the antioxidant enzymes genes expression when exposed to Cd stress. These findings facilitate further investigation of the functional and molecular characteristics of BcBPC9 in response to abiotic stress. The outcomes of this study provide a crucial foundation for future research on improving plant growth and protecting vegetable production.

Function of Transcription Factors PoMYB12, PoMYB15, and PoMYB20 in Heat Stress and Growth of Pleurotus ostreatus.

MYB transcription factors (TFs) have been extensively studied in plant abiotic stress responses and growth and development. However, the role of MYB TFs in the heat stress response and growth and development of Pleurotus ostreatus remains unclear. To investigate the function of PoMYB12, PoMYB15, and PoMYB20 TFs in P. ostreatus, mutant strains of PoMYB12, PoMYB15, and PoMYB20 were generated using RNA interference (RNAi) and overexpression (OE) techniques. The results indicated that the mycelia of OE-PoMYB12, OE-PoMYB20, and RNAi-PoMYB15 mutant strains exhibited positive effects under heat stress at 32 °C, 36 °C, and 40 °C. Compared to wild-type strains, the OE-PoMYB12, OE-PoMYB20, and RNAi-PoMYB15 mutant strains promoted the growth and development of P. ostreatus. These mutant strains also facilitated the recovery of growth and development of P. ostreatus after 24 h of 36 °C heat stress. In conclusion, the expression of PoMYB12 and PoMYB20 supports the mycelium's response to heat stress and enhances the growth and development of P. ostreatus, whereas PoMYB15 produces the opposite effect.

ZFP37, C3H, NAC94, and bHLH148 transcription factors regulate cultivar-specific drought response by modulating r40C1 gene expression in rice

Lectins are gradually gaining importance in regulating abiotic stress response in plants. Among them, the R40 family plays pivotal role in regulating drought response. The expression of the Osr40C1 positively correlates with the degree of drought tolerance in indica rice cultivars. Although the mechanism of Osr40C1-mediated drought tolerance is well characterized, the gene's regulation under drought remains obscure. Here, we demonstrate that the Osr40C1 promoter is activated under drought to induce its transcription. A number of single nucleotide variations in the Osr40C1 promoter of the drought-tolerant IR36 and sensitive MTU1010 cultivar are detected. However, promoter swapping analysis reveals that these variations in the promoter sequence do not explain the cultivar-specific expression pattern of this gene. Next, we identified the transcription factors that interact with the Osr40C1 promoter. Among these transcription factors, OsZFP37, OsC3H, OsNAC94, and OsbHLH148 display significantly higher transcript abundance in IR36 compared with MTU1010. Furthermore, overexpression of each of these transcription factors confers drought tolerance, whereas their silencing leads to drought sensitivity. Interestingly, the Osr40C1 expression is significantly up-regulated in the transcription factor overexpression lines, while its expression is undetectable in the silencing lines. Together our study highlights how different transcription factors regulate the cultivar-specific expression pattern of Osr40C1 in rice.

A Transcription Factor SlNAC4 Gene of Suaeda liaotungensis Enhances Salt and Drought Tolerance through Regulating ABA Synthesis.

The NAC (NAM, ATAF1/2 and CUC2) transcription factors are ubiquitously distributed in plants and play critical roles in the construction of plant organs and abiotic stress response. In this study, we described the cloning of a Suaeda liaotungensis K. NAC transcription factor gene SlNAC4, which contained 1450 bp, coding a 331 amino acid. We found that SlNAC4 was highly expressed in stems of S. liaotungensis, and the expression of SlNAC4 was considerably up-regulated after salt, drought, and ABA treatments. Transcription analysis and subcellular localization demonstrated that the SlNAC4 protein was located both in the nucleus and cytoplasm, and contained a C-terminal transcriptional activator. The SlNAC4 overexpression Arabidopsis lines significantly enhanced the tolerance to salt and drought treatment and displayed obviously increased activity of antioxidant enzymes under salt and drought stress. Additionally, transgenic plants overexpressing SlNAC4 had a significantly higher level of physiological indices. Interestingly, SlNAC4 promoted the expression of ABA metabolism-related genes including AtABA1, AtABA3, AtNCED3, AtAAO3, but inhibited the expression of AtCYP707A3 in overexpression lines. Using a yeast one-hybrid (Y1H) assay, we identified that the SlNAC4 transcription factor could bind to the promoters of those ABA metabolism-related genes. These results indicate that overexpression of SlNAC4 in plants enhances the tolerance to salt and drought stress by regulating ABA metabolism.

Genome-wide identification and characterization of the diacylglycerol kinase (DGK) gene family in Populus trichocarpa

Diacylglycerol kinase (DGK) is an enzyme that converts diacylglycerol to phosphatidic acid and plays pivotal roles in plant biotic and abiotic stress responses. Although the Populus trichocarpa genome has been sequenced, characterization of the PtDGK gene family has not been reported. In this study, we performed genome-wide investigation and expression pattern analysis of the PtDGK gene family in poplar. In total, 7 PtDGK genes (PtDGK1-PtDGK7) were identified and divided into three clusters, namely, Cluster I (3), Cluster II (2), and Cluster III (2). Sequence analysis revealed that all members contained two conserved domains, DAGKa and DAGKc, while Cluster I contained two additional DAG/PE-binding domains and was more conserved in the protein three-dimensional structure. In addition, the members of the three PtDGK subfamilies had similar gene structures, motif compositions and conserved domains. Chromosome localization revealed that the 7 PtDGK members were located on 7 different chromosomes, with each chromosome containing only one PtDGK member. Two segmental duplication gene pairs were found in Populus trichocarpa, which have undergone purification selection during evolution. Collinearity analysis demonstrated that Populus trichocarpa had more collinear gene pairs with Arabidopsis thaliana than with Vitis vinifera. The promoter regions were rich in hormone and stress response cis-acting elements. RNA-seq transcriptome data revealed different expression patterns of the PtDGKs in different tissues and under various hormone treatments (salicylic acid and jasmonic acid), abiotic stresses (salt, drought, cold and heat), and biotic stresses (pests and pathogens). Quantitative real-time PCR analysis showed that DGK3 and DGK5 can be induced by salt treatment. This work provides the first characterization of PtDGKs in poplar and suggests their importance in biotic and abiotic stresses, which will provide guidance for further research on the understanding and functional dissection of PtDGKs in the future.

Comprehensive genome-wide analysis of the DREB gene family in Moso bamboo (Phyllostachys edulis): evidence for the role of PeDREB28 in plant abiotic stress response.

Dehydration response element binding (DREB) proteins are vital for plant abiotic stress responses, but the understanding of DREBs in bamboo, an important sustainable non-timber forest product, is limited. Here we conducted a comprehensive genome-wide analysis of the DREB gene family in Moso bamboo, representing the most important running bamboo species in Asia. In total, 44 PeDREBs were identified, and information on their gene structures, protein motifs, phylogenetic relationships, and stress-related cis-regulatory elements (CREs) was provided. Based on the bioinformatical analysis, we further analyzed PeDREBs from the A5 group and found that four of five PeDREB transcripts were induced by salt, drought, and cold stresses, and their proteins could bind to stress-related CREs. Among these, PeDREB28 was selected as a promising candidate for further functional characterization. PeDREB28 is localized in nucleus, has transcriptional activation activity, and could bind to the DRE- and coupling element 1- (CE1) CREs. Overexpression of PeDREB28 in Arabidopsis and bamboo improved plant abiotic stress tolerance. Transcriptomic analysis showed that broad changes due to the overexpression of PeDREB28. Furthermore, 628 genes that may act as the direct PeDREB28 downstream genes were identified by combining DAP-seq and RNA-seq analysis. Moreover, we confirmed that PeDREB28 could bind to the promoter of pyrabactin-resistance-like gene (DlaPYL3), which is a homolog of abscisic acid receptor in Arabidopsis, and activates its expression. In summary, our study provides important insights into the DREB gene family in Moso bamboo, and contributes to their functional verification and genetic engineering applications in the future.

Brassica rapa Nitrate Transporter 2 (BrNRT2) Family Genes, Identification, and Their Potential Functions in Abiotic Stress Tolerance.

Nitrate transporter 2 (NRT2) proteins play vital roles in both nitrate (NO3-) uptake and translocation as well as abiotic stress responses in plants. However, little is known about the NRT2 gene family in Brassica rapa. In this study, 14 NRT2s were identified in the B. rapa genome. The BrNRT2 family members contain the PLN00028 and MATE_like superfamily domains. Cis-element analysis indicated that regulatory elements related to stress responses are abundant in the promoter sequences of BrNRT2 genes. BrNRT2.3 expression was increased after drought stress, and BrNRT2.1 and BrNRT2.8 expression were significantly upregulated after salt stress. Furthermore, protein interaction predictions suggested that homologs of BrNRT2.3, BrNRT2.1, and BrNRT2.8 in Arabidopsis thaliana may interact with the known stress-regulating proteins AtNRT1.1, AtNRT1.5, and AtNRT1.8. In conclusion, we suggest that BrNRT2.1, BrNRT2.3, and BrNRT2.8 have the greatest potential for inducing abiotic stress tolerance. Our findings will aid future studies of the biological functions of BrNRT2 family genes.

A mulberry 9-cis-epoxycarotenoid dioxygenase gene MaNCED1 is involved in plant growth regulation and confers salt and drought tolerance in transgenic tobacco.

The phytohormone abscisic acid (ABA) is vital in regulating root elongation, seed germination, and abiotic stress responses in plants. Conversely, the mechanisms of ABA in mulberry root growth, seed germination, and abiotic stress responses are poorly understood. Here, we reported that exogenous ABA and drought treatment inhibited the growth of mulberry seedlings but significantly increased the ratio of root/stem. Inhibition of ABA synthesis by fluridone and sodium tungstate resulted in the decrease of root/stem ratio. We also showed that the expression of MaNCED1 in the root was strongly induced by drought and salt stress. Increasing the expression of MaNCED1 in tobacco using overexpression leads to increased root elongation and reduced seed germination. Compared with the wild type, the accumulation of H2O2 and MDA was reduced, while the POD activity and proline content was increased in the transgenic plants after drought and salt treatment. Further studies revealed increased resistance to drought and salt stress in MaNCED1 overexpressed tobaccos. Meanwhile, the auxin and ethylene signal pathway-related gene expression levels increased in MaNCED1 overexpressed tobaccos. This study demonstrated the roles of mulberry MaNCED1 in regulating plant development and abiotic stress responses. It gave further insights into the coordinated regulation of ABA, auxin, and ethylene in seed growth and germination.

Genome-Wide Identification, Phylogenetic and Expression Analysis of the B-Box Gene Family in the Woodland Strawberry (Fragaria vesca)

The strawberry (Fragaria × ananassa Duch.) is an important horticultural crop that is widely grown all over the world. Its sweetness, aroma, nutritional value and bright color make it popular. The woodland strawberry (Fragaria vesca) is a model plant for studying non-climacteric fruits because its respiration rate does not change significantly during fruit ripening. The B-box (BBX) protein family is made up of zinc-finger transcription factors important in plant growth and development. In this study, we identified 22 FveBBX genes from the newly released woodland strawberry genome database by comprehensive bioinformatics analysis. Phylogenetic analysis divided these FveBBX genes into five subfamilies. A promoter cis-acting element analysis detected 29 elements related to plant development, light response, abiotic stress and hormone response in the promoter of FveBBX genes. According to transcriptome data, relatively few BBX genes had tissue-specific expression, with examples including FveBBX12, which was expressed only in pre-fertilization cortex and pitch, and FveBBX19, which was specifically expressed in mature anthers. During fruit ripening, the expressions of eight FveBBX genes decreased by more than two-fold, and three FveBBX gene expressions increased more than two-fold both in “Ruegen” and “Yellow Wonder”. After cold and heat stresses, around half of the FveBBX genes displayed altered expression, especially FveBBX16 which showed an 8.3-fold increase in expression after heat treatment, while FveBBX14 showed at least an 11-fold decrease in expression after cold treatment. According to the result of quantitative real-time PCR (qRT-PCR), FveBBX genes’ expression differed depending on the photoperiod. Notably, FveBBX7 gene expression was the opposite during the first 16 h of the long-day (LD) and short-day (SD) conditions. This study provides helpful information for further research on BBX gene activity of the woodland strawberry in plant growth and development and adaptation to temperature and photoperiod environmental conditions.

Phosphoribosyltransferases and Their Roles in Plant Development and Abiotic Stress Response.

Glycosylation is a widespread glycosyl modification that regulates gene expression and metabolite bioactivity in all life processes of plants. Phosphoribosylation is a special glycosyl modification catalyzed by phosphoribosyltransferase (PRTase), which functions as a key step in the biosynthesis pathway of purine and pyrimidine nucleotides, histidine, tryptophan, and coenzyme NAD(P)+ to control the production of these essential metabolites. Studies in the past decades have reported that PRTases are indispensable for plant survival and thriving, whereas the complicated physiological role of PRTases in plant life and their crosstalk is not well understood. Here, we comprehensively overview and critically discuss the recent findings on PRTases, including their classification, as well as the function and crosstalk in regulating plant development, abiotic stress response, and the balance of growth and stress responses. This review aims to increase the understanding of the role of plant PRTase and also contribute to future research on the trade-off between plant growth and stress response.

Identification and characterization of the Cyamopsis tetragonoloba transcription factor MYC (CtMYC) under drought stress

The MYC transcription factor (TF) has a variety of roles in abiotic stress responses of plants. In the present work, MYC TF named CtMYC (Cymopsis tetragonoloba) from guar plant, which is induced by drought stress, was identified. The mature leaves of guar were employed to detect the full-length CtMYC TF on the 8th day of drought stress. The CtMYC gene showed tissue-specific expression and up regulated under drought stress conditions as compared to the control and maximum expression was observed in mature leaves. Additionally, CtMYC TF was cloned and expressed in E. coli Rosetta cells and CtMYC protein was purified. The circular dichroism (CD) analysis revealed the presence of helical content and beta sheets and in the presence of genomic DNA the conformational changes were observed in secondary structure, which showed DNA binding potential of CtMYC. These results were analyzed by CD and fluorescence studies. In silico studies reveal the presence of conserved bHLH domain and DNA-binding amino acid residues His, Glu and Arg in CtMYC. This is first report on CtMYC TF with DNA binding potential that is responsive to drought. This study provides the structure and characterization of CtMYC TF and DNA binding ability in drought tolerance mechanism in guar.

Melatonin enhances KCl salinity tolerance by maintaining K+ homeostasis in Malus hupehensis.

Large amounts of potash fertilizer are often applied to apple (Malus domestica) orchards to enhance fruit quality and yields, but this treatment aggravates KCl-based salinity stress. Melatonin (MT) is involved in a variety of abiotic stress responses in plants. However, its role in KCl stress tolerance is still unknown. In the present study, we determined that an appropriate concentration (100 μm) of MT significantly alleviated KCl stress in Malus hupehensis by enhancing K+ efflux out of cells and compartmentalizing K+ in vacuoles. Transcriptome deep-sequencing analysis identified the core transcription factor gene MdWRKY53, whose expression responded to both KCl and MT treatment. Overexpressing MdWRKY53 enhanced KCl tolerance in transgenic apple plants by increasing K+ efflux and K+ compartmentalization. Subsequently, we characterized the transporter genes MdGORK1 and MdNHX2 as downstream targets of MdWRKY53 by ChIP-seq. MdGORK1 localized to the plasma membrane and enhanced K+ efflux to increase KCl tolerance in transgenic apple plants. Moreover, overexpressing MdNHX2 enhanced the KCl tolerance of transgenic apple plants/callus by compartmentalizing K+ into the vacuole. RT-qPCR and LUC activity analyses indicated that MdWRKY53 binds to the promoters of MdGORK1 and MdNHX2 and induces their transcription. Taken together, our findings reveal that the MT-WRKY53-GORK1/NHX2-K+ module regulates K+ homeostasis to enhance KCl stress tolerance in apple. These findings shed light on the molecular mechanism of apple response to KCl-based salinity stress and lay the foundation for the practical application of MT in salt stress.

Overexpression of OsHAD3, a Member of HAD Superfamily, Decreases Drought Tolerance of Rice

Haloacid dehalogenase-like hydrolase (HAD) superfamily have been shown to get involved in plant growth and abiotic stress response. Although the various functions and regulatory mechanism of HAD superfamily have been well demonstrated, we know little about the function of this family in conferring abiotic stress tolerance to rice. Here, we report OsHAD3, a HAD superfamily member, could affect drought tolerance of rice. Under drought stress, overexpression of OsHAD3 increases the accumulation of reactive oxygen species and malondialdehyde than wild type. OsHAD3-overexpression lines decreased but antisense-expression lines increased the roots length under drought stress and the transcription levels of many well-known stress-related genes were also changed in plants with different genotypes. Furthermore, overexpression of OsHAD3 also decreases the oxidative tolerance. Our results suggest that overexpression of OsHAD3 could decrease the drought tolerance of rice and provide a new strategy for improving drought tolerance in rice.

Transcript-wide identification and expression pattern analysis to comprehend the roles of AP2/ERF genes under development and abiotic stress in Trichosanthes kirilowii

BackgroundThe APETALA 2/ ethylene-responsive element binding factors (AP2/ERF), are thought to be associated with plant abiotic stress response, and involved in some plant hormone signaling pathways. Trichosanthes kirilowii is an important edible and medicinal crop, so far no research has been conducted on the TkAP2/ERF genes.ResultIn this study, a total of 135 TkERFs were identified, these genes were divided into 4 subfamilies and clustered into 13 groups. Moreover, 37 paralogous pairs were identified, with only two having Ka/Ks values greater than 1, proving that most TkERF genes underwent purifying selection during evolution. Co-expression networks constructed using transcriptome data at various flowering stages revealed that 50, 64, and 67 AP2/ERF genes correlated with members of the ethylene, gibberellin, and abscisic acid signaling pathways, respectively. When tissue cultured seedlings were treated with ETH, GA3 and ABA, 11, 12 and 17 genes were found to be up-regulated, respectively, suggesting that some members of the TkERF gene family may be involved in plant hormone signaling pathways. And under 4 ℃, PEG and NaCl treatment, 15, 20 and 19 genes were up-regulated, respectively, this suggested that these selected genes might be involved in plant abiotic stresses.ConclusionsOverall, we identified 135 AP2/ERF family members, a comprehensive analysis of AP2/ERF gene expression patterns by RNA-seq and qRT-PCR showed that they played important roles in flower development and abiotic stress. This study provided a theoretical basis for the functional study of TkAP2/ERF genes and the genetic improvement of T. kirilowii.

Characterization and Potential Function Analysis of the SRS Gene Family in Brassica napus.

SRS (SHI-related sequence) transcription factors play a crucial role in plant growth, development, and abiotic stress response. Although Brassica napus (B. napus) is one of the most important oil crops in the world, the role of SRS genes in B. napus (BnSRS) has not been well investigated. Therefore, we employed a bioinformatics approach to identify BnSRS genes from genomic data and investigated their characteristics, functions, and expression patterns, to gain a better understanding of how this gene family is involved in plant development and growth. The results revealed that there were 34 BnSRS gene family members in the genomic sequence of B. napus, unevenly distributed throughout the sequence. Based on the phylogenetic analysis, these BnSRS genes could be divided into four subgroups, with each group sharing comparable conserved motifs and gene structure. Analysis of the upstream promoter region showed that BnSRS genes may regulate hormone responses, biotic and abiotic stress response, growth, and development in B. napus. The protein-protein interaction analysis revealed the involvement of BnSRS genes in various biological processes and metabolic pathways. Our analysis of BnSRS gene expression showed that 23 BnSRS genes in the callus tissue exhibited a dominant expression pattern, suggesting their critical involvement in cell dedifferentiation, cell division, and tissue development. In addition, association analysis between genotype and agronomic traits revealed that BnSRS genes may be linked to some important agronomic traits in B. napus, suggesting that BnSRS genes were widely involved in the regulation of important agronomic traits (including C16.0, C18.0, C18.1, C18.2 C18.3, C20.1, C22.1, GLU, protein, TSW, and FFT). In this study, we predicted the evolutionary relationships and potential functions of BnSRS gene family members, providing a basis for the development of BnSRS gene functions which could facilitate targeted functional studies and genetic improvement for elite breeding in B. napus.

Comprehensive identification of glutathione peroxidase (GPX) gene family in response to abiotic stress in pepper (Capsicum annuum L.)

Plant glutathione peroxidase (GPX) plays an important role in the maintenance of cell homeostasis and in the antioxidant response in plants. In this study, the peroxidase (GPX) gene family was identified in the whole genome of pepper using bioinformatic method. As a result, a total of 5 CaGPX genes were identified, which were unevenly distributed on 3 of the 12 chromosomes of pepper genome. Based on phylogenetic analysis, 90 GPX genes in 17 species from lower plants to higher plants can be divided into 4 groups (GroupⅠ, Group Ⅱ, Group Ⅲ, Group Ⅳ). The MEME Suite analysis of GPX proteins shows that all these proteins contain four highly conserved motifs, as well as other conserved sequences and amino acid residues. Gene structure analysis revealed the conservative exon-intron organization pattern of these genes. In the promoter region of CaGPX genes, many cis elements of plant hormone and abiotic stress response were identified in each of CaGPX proteins. In addition, expression patterns of CaGPX genes in different tissues, developmental stages and responses to abiotic stress were also performed. The results of qRT-PCR showed that the transcripts of CaGPX genes varied greatly under abiotic stress at different time points. There results suggest that the GPX gene family of pepper may play a role in plant development andstress response. In conclusion, our research provides new insights into the evolution of pepper GPX gene family, and understanding for functional of these genes in response to abiotic stresses.

Function of Soybean miR159 Family Members in Plant Responses to Low Phosphorus, High Salinity, and Abscisic Acid Treatment

MicroRNAs (miRNAs) regulate plant growth and development and plant responses to biotic and abiotic stresses. Although extensive studies show that miR159 family members regulate leaf and flower development in Arabidopsis thaliana, the roles of miRNAs in soybean (Glycine max) are poorly understood. Here, we identified six MIR159 genes in soybean, MIR159a–MIR159f, and investigate their expression patterns in plants under low-phosphorus (low-P), NaCl, or abscisic acid (ABA) treatments. In soybean leaves, MIR159e and MIR159f expression was induced by low-P treatment, while in roots, MIR159b, MIR159c, MIR159e, and MIR159f expression was upregulated. In flowers, low-P led to upregulation of MIR159a, MIR159b, MIR159c, and MIR159f but downregulation of MIR159d and MIR159e. In soybean nodules, MIR159b was upregulated but MIR159a, MIR159c, and MIR159d was downregulated under P deficiency. NaCl treatment induced MIR159a, MIR159b, MIR159c, and MIR159e expression in leaves and MIR159a–MIR159f expression in roots. ABA treatment upregulated MIR159a, MIR159b, and MIR159c but downregulated MIR159d, MIR159e, and MIR159f in leaves. These results suggest that miR159 family members function in plant abiotic stress responses. Moreover, total P content in leaves was significantly lower in plants overexpressing MIR159e than in the wild type, suggesting that miR159e may regulate P absorption and transport in soybean plants.

Drought and temperature stresses impact pollen production and autonomous selfing in a California wildflower, Collinsia heterophylla

AbstractOngoing climatic changes have altered growing conditions for plants by limiting water availability and inducing unprecedented temperature increases, eliciting plant functional responses that compromise floral trait expression, reduce pollen production and promote early self‐pollination. In a controlled greenhouse study, plants of Collinsia heterophylla, an annual mixed‐mated hermaphrodite, were grown under temperature and water stresses. Floral trait responses and related effects on plant reproductive success were recorded. Plants grown under temperature and water stresses were shorter and had fewer leaves at flowering than control plants. Temperature‐stressed plants flowered earlier and had smaller flowers that produced fewer per capita pollen grains than control and water‐stressed plants. While lifetime flower production in plants experiencing temperature stress alone or water stress alone was similar to control plants, those receiving combined temperature and water stresses had significantly lower lifetime flower production. Abiotic stress did not affect investment in female traits such as ovule number per flower, but impacted male traits seen as fewer pollen grains per flower. In plants experiencing abiotic stress, an increase in autonomous self‐pollination was facilitated through a compromise in herkogamy, a sexual interference mechanism that promotes cross‐pollination. Spatial separation between stigma and anther, a measure of herkogamy was zero or negative in stressed plants. Thus, abiotic stress responses in plants did not compromise plant reproductive success as autonomous selfing was augmented. In nature, such responses will likely reduce available nutrition for pollinators through decreased flower and pollen production.