The NAC-like transcription factor Si NAC110 in foxtail millet(Setaria italica L.) confers tolerance to drought and high salt stress through an ABA independent signaling pathway

Foxtail millet（Setaria italica（L.）P.Beauv）is a naturally stress tolerant crop.Compared to other gramineous crops,it has relatively stronger drought and lower nutrition stress tolerance traits.To date,the scope of functional genomics research in foxtail millet（S.italic L.）has been quite limited.NAC（NAM,ATAF1/2 and CUC2）-like transcription factors are known to be involved in various biological processes,including abiotic stress responses.In our previous foxtail millet（S.italic L.）RNA seq analysis,we found that the expression of a NAC-like transcription factor,SiNAC110,could be induced by drought stress;additionally,other references have reported that SiNAC110 expression could be induced by abiotic stress.So,we here selected SiNAC110 for further characterization and functional analysis.First,the predicted SiNAC110 protein encoded indicated SiNAC110 has a conserved NAM（no apical meristem）domain between the 11–139 amino acid positions.Phylogenetic analysis then indicated that SiNAC110 belongs to subfamily III of the NAC gene family.Subcellular localization analysis revealed that the SiNAC110-GFP fusion protein was localized to the nucleus in Arabidopsis protoplasts.Gene expression profiling analysis indicated that expression of SiNAC110 was induced by dehydration,high salinity and other abiotic stresses.Gene functional analysis using SiNAC110 overexpressed Arabidopsis plants indicated that,under drought and high salt stress conditions,the seed germination rate,root length,root surface area,fresh weight,and dry weight of the SiNAC110 overexpressed lines were significantly higher than the wild type（WT）,suggesting that the SiNAC110 overexpressed lines had enhanced tolerance to drought and high salt stresses.However,overexpression of SiN AC110 did not affect the sensitivity of SiNAC110 overexpressed lines to abscisic acid（ABA）treatment.Expression analysis of genes involved in proline synthesis,Na＋/K＋transport,drought responses,and aqueous transport proteins were higher in the SiNAC110overexpressed lines than in the WT,whereas expression of ABA-dependent pathway genes did not change.These results indicated that overexpression of SiNAC110 conferred tolerance to drought and high salt stresses,likely through influencing the regulation of proline biosynthesis,ion homeostasis and osmotic balance.Therefore,SiNAC110 appears to function in the ABA-independent abiotic stress response pathway in plants.

Differential Expression of microRNAs in Maize Inbred and Hybrid Lines during Salt and Drought Stress

Here, we analyzed whether the microRNA (miRNA) expression levels differ between maize inbred lines B73 and Mo17 and their reciprocal hybrids under salt and drought stress. We found that miR156, miR164, miR166, miR168, miR171 and miR319 are differentially expressed under abiotic stress. Interestingly, Mo17 × B73 showed the strongest change in miRNA expression in response to salt or drought stress, and was also the most resilient line when under abiotic stress in terms of water loss. In summary, our findings open the possibility that differential miRNA expression levels might be involved in heightened stress tolerance in maize hybrids.

Overexpression of GmProT1 and GmProT2 increases tolerance to drought and salt stresses in transgenic Arabidopsis

financially supported by the Genetically Modified Organisms Breeding Major Projects of China （2014ZX08004）;the National Natural Science Foundation of China （31301340）;the Modern Agro-industry Technology Research System of China （CARS-004-PS10）;the Program for Changjiang Scholars and Innovative Research Team in University, China （PCSIRT13073）;the Jiangsu Collaborative Innovation Center for Modern Crop Production;an Openend Fund by State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, China （ZW2013009）

Photosynthetic Characteristics of Clerodendrum trichotomum Thumb. Responses to Drought, Salt and Water-logging Stresses

In order to reveal the photosynthetic characteristics of C. trichotomum responses to drought, salt and water-logging stresses, one-year-old potted seedlings were taken as materials, and the several stresses including natural drought, submergence stress, water-logging and different salt treatments （0.2%, 0.4%, 0.6% and 0.8% NaCl） were carried out on August 15, 2012. The morphological and photosynthetic characteristics were observed and determined. The results showed that adverse enviromental stress had a significant effect on the morphological changes and photosynthetic characteristics of C. trichotomum. On the 14th day after natural drought, the leaves wilted and could not recovery at night, and 60% of the seedlings could recover after re-watering. From the 7th day to the 10th day after submergence stress treatment, the 2nd and the 3rd leaves at the base of 60% seedling turned yellow and the lenticels were observed. At the early stage of water-logging stress, white lenticels appeared at the base of seedlings, and the leaves wilted, chlorina and fallen off on the 8th day. A large number of leaves fallen off under 0.6% NaCl or more salt stress, and even the whole plant died. The chlorophyll content, net photosynthetic rate （Pn） and transpiration rate （Tr） decreased gradually with the stress process, such as 8 days after natural drought, less than 0.4% salt stress and water-logging stress, but the changes were not significant compared with those of the control. With the increase of the stress intensity and the prolonged time, the changes of photosynthetic index were significant. All the results indicated that C. trichotomum had a certain degree of tolerance to drought, water and salt, but it was not suitable for living, in water-logging condition for a long time.

Fourier transform-infrared studies on the effects of salt and drought stress on the chemical composition and pro-tein conformation changes in Arabidopsis leaves

We examined the changes of chemical composition and protein conformation in Arabidopsis leaves by Fourier transform-infrared (FT-IR) spectrometry Arabidopsis under 50 mmol/L NaCl salt and -0.5 mPa polyethylene glycols 8000 (PEG 8000) drought stress during the early stages of growth.We primarily analyzed the absorption band areas in the 1,745 cm-1 (ester),1,600-1,700 cm-1 (amide I),and 1,100 cm-1 (carbohydrate) changes under salt stress and drought stress within 24 hours.The results showed that ester content declined at the beginning and then increased steadily during 24 hours of drought stress.But under salt stress,it de-clined steadily,and it was about 40 percent of the control after 24 hours.The protein synthesis increased by 25 percent after one hour of salt stress and then reached about 85 percent of the control after 24 hours.Under drought stress,the protein synthesis de-creased and reached aminimal level at the 4-hr time point;it then recovered to the control level at the 24-hr point.The patterns of the accumulation of carbohydrates in the 1,100 cm-1 band areas resembled that of amide I band changes under drought stress and salt stress.Analyzing the ratio A1,627cm-1/A1,658cm-1 under drought stress revealed that the leaves’ entire protein structure maintained a higher-level ordered form than did those under salt stress.Thus our results indicate the existence of different strategies of the Arabidopsis adaptation to salt stress and drought stress.

Chemically Induced Mutants of <i>Brassica oleracea var. botrytis</i>Maintained Stable Resistance to Drought and Salt Stress after Regeneration and Micropropagation

Investigation was made to confirm the stability of drought and salt stress tolerance in cauliflower (Brassica oleracea var.botrytis) mutants after regeneration and micropropagation. The N-nitroso-N-ethyleurea (NEU) and N-nitroso-N-methylurea (NMU) induced mutants of cauliflower were created and screened for drought and salt stress tolerance. The highly tolerant mutants were selected, regenerated by tissue culture techniques, screened again for drought and salt tolerance under in-vitro and in-vivo conditions, correlated the response of in-vitro and in-vivo plants within a clone. Free proline levels in clones were correlated with stress tolerance. Results confirmed the persistence of mutations in clones with enhanced resistance levels to stresses over control plants. The regenerated in-vitro and in-vivo plants within a clone showed a positive significant correlation for drought (R2 = 0.663) and salt (R2 = 0.647) resistance that confirms the stability of mutation in clones after generations. Proline showed a positive and significant correlation with drought (R2 = 0.524) and salt (R2 = 0.786) tolerance. Conclusively, drought and salt resistance can be successfully enhanced in cauliflower by chemical mutagenesis. Further molecular analysis is recommended to study these mutants.

Characters and structures of the nucleobase-ascorbate transporters(NAT)family genes in Gossypium hirsutum and their roles in responding to salt and drought stresses

Background: Nucleobase-ascorbate transporters(NAT), synonymously called nucleobase-cation symporter 2(NCS2) proteins, were earlier reported to be involved in plant growth, development and resistance to stress. Previous studies concluded that s a polymorphic SNP associated with NAT12 was significant di erent between salt-tolerant and salt-sensitive materials of upland cotton. In current study, a comprehensive analysis of NAT family genes was conducted for the first time in cotton.Results: In this study, we discovered 32, 32, 18, and 16 NAT genes in Gossypium hirsutum, G. barbadense, G. raimondii and G. arboreum, respectively, which were classified into four groups(groups I–IV) based on the multiple sequence analysis. These GhNAT genes were unevenly distributed on At and Dt sub-genome in G. hirsutum. Most GhNAT members in the same group had similar gene structure characteristics and motif composition. The collinearity analysis revealed segmental duplication as well as tandem duplication contributing to the expansion of the GhNATs. The analysis of cis-acting regulatory elements of GhNATs showed that the function of GhNAT genes in cotton might be related to plant hormone and stress response. Under di erent conditions, the expression levels further suggested the GhNAT family genes were associated with plant response to various abiotic stresses. GhNAT12 was detected in the plasma membrane. And it was validated that the GhNAT12 gene played an important role in regulating cotton resistance to salt and drought stress through the virus-induced gene silencing(VIGS) analysis.Conclusions: A comprehensive analysis of NAT gene family was performed in cotton, including phylogenetic analysis, chromosomal location, collinearity analysis, motifs, gene structure and so on. Our results will further broaden the insight into the evolution and potential functions of NAT genes in cotton. Current findings could make significant contribution towards screening more candidate genes related to biotic and abiotic resistance for the improvement in cotton.

Genome wide identification and characterization of MAPK genes reveals their potential in enhancing drought and salt stress tolerance in Gossypium hirsutum

Background:The cotton crop is universally considered as protein and edible oil source besides the major contributor of natural fiber and is grown in tropical and subtropical regions around the world Unpredicted environmental stresses are becoming significant threats to sustainable cotton production,ultimately leading to a substantial irreversible economic loss.Mitogen-activated protein kinase(MAPK)is generally considered essential for recognizing environmental stresses through phosphorylating downstream signal pathways and plays a vital role in numerous biological processes.Results:We have identified 74 MAPK genes across cotton,41 from G.hirsutum,19 from G.raimondii,whereas 14 have been identified from G.arboreum.The MAPK gene-proteins have been further studied to determine their physicochemical characteristics and other essential features.In this perspective,characterization,phylogenetic relationship,chromosomal mapping,gene motif,cis-regulatory element,and subcellular localization were carried out.Based on phylogenetic analysis,the MAPK family in cotton is usually categorized as A,B,C,D,and E clade.According to the results of the phylogenic relationship,cotton has more MAPKS genes in Clade A than Clade B.The cis-elements identified were classified into five groups(hormone responsiveness,light responsiveness,stress responsiveness,cellular development,and binding site).The prevalence of such elements across the promoter region of these genes signifies their role in the growth and development of plants.Seven GHMAPK genes(GH_A07G1527,GH_D02G1138,GH_D03G0121,GH_D03G1517,GH_D05G1003,GH_D11G0040,and GH_D12G2528)were selected,and specific tissue expression and profiling were performed across drought and salt stresses.Results expressed that six genes were upregulated under drought treatment except for GH_D11G0040 which is downregulated.Whereas all the seven genes have been upregulated at various hours of salt stress treatment.Conclusions:RNA sequence and qPCR results showed that genes as differentially expressed across both vegetative and reproductive plant parts.Similarly,the qPCR analysis showed that six genes had been upregulated substantially through drought treatment while all the seven genes were upregulated across salt treatments.The results of this study showed that cotton GHMPK3 genes play an important role in improving cotton resistance to drought and salt stresses.MAPKs are thought to play a significant regulatory function in plants’responses to abiotic stresses according to various studies.MAPKs’involvement in abiotic stress signaling and innovation is a key goal for crop species research,especially in crop breeding.

Genome-Wide Identification of the F-box Gene Family and Expression Analysis under Drought and Salt Stress in Barley

The F-box protein-encoding gene family plays an essential role in plant stress resistance.In present study,126 non-redundant F-box genes were identified in barley(Hordeum vulgare L.,Hv).The corresponding proteins contained 165–887 amino acid residues and all were amphiphilic,except 5 proteins.Phylogenetic analysis of F-box protein sequences in barley and stress-related F-box protein sequences in wheat and Arabidopsis thaliana(At)was used to classify barley F-box genes are divided into 9 subfamilies(A–I).A structure-based sequence alignment demonstrated that F-box proteins were highly conserved with a total of 10 conserved motifs.In total,124 F-box genes were unevenly distributed on 7 chromosomes;another 2 genes have not been anchored yet.The gene structure analysis revealed high variability in the number of exons and introns in F-box genes.Comprehensive analysis of expression profiles and phylogenetic tree analysis,a total of 12 F-box genes that may be related to stress tolerance in barley were screened.Of the 12 detected F-box genes,8 and 10 were upregulated after drought and salt stress treatments,respectively,using quantitative real-time polymerase chain reaction(qRT-PCR).This study is the first systematic analysis conducted on the F-box gene family in barley,which is of great importance for clarifying this family’s bioinformatic characteristics and elucidating its function in barley stress resistance.These results will serve as a theoretical reference for subsequent research on molecular regulation mechanisms,genetic breeding,and improvement.

Transgenic Poplar Plants for the Investigation of ABA-Dependent Salt and Drought Stress Adaptation in Trees

Important functions of the plant hormone abscisic acid (ABA) in stress reactions, growth and photosynthetic processes are extensively studied in the model plant Arabidopsis thaliana. This paper investigates the importance of Moco-sulphurase ABA3 and aldehyde oxidase (AO) on ABA-biosynthesis in Populus × canescens. ABA3 is essential for activation of the molybdenum enzymes AO and xanthine dehydrogenase (XDH). AO itself catalyzes the last step in ABA-biosynthesis. Generation of transgenic poplar plants altered in ABA3 and AO-activity using RNAi knock down and overexpression was performed. Whereas RNAi-AO plants show a specific loss of AO activity, the RNAi-ABA3 plants has a strongly reduced activity of both molybdenum enzymes: AO and XDH. Constructs of AO and ABA3-promoters fused to β-glucuronidase provide the basis to investigate transcriptional regulation of ABA-biosynthetic processes under stress conditions. Application of high salt concentrations and different drought stress intensities does change the endogenous AO or XDH neither on the side of transcription nor on protein activity. On phytohormone level however, water loss leads to increased ABA-amounts regardless of whether transgenic or wildtype plants are studied. Salt application resulted in higher ABA-levels in all analyzed plant lines. The down regulation of AO in the two different RNAi-plant lines strongly prevented a wildtype-like increase of ABA-levels. Whereas the WT plants accumulated up to 6000 ng ABA g-1 FW-1 after 16 h of salt stress exposure, plants of the RNAi lines revealed a markedly lower increase of only up to 2000 ng ABA g-1 FW-1. Opposing to these observations, ABA-levels increased during drought without any influence by the RNAi-effect. These results revealed that although stresses did not result in a visible increased AO-activity, ABA-production was influenced by AO and ABA3 at least under salinity.

Overexpression of the Suaeda salsa SsNHX1 gene confers enhanced salt and drought tolerance to transgenic Zea mays

Maize is one of the most important crops worldwide, but it suffers from salt stress when grown in saline-alkaline soil. There is therefore an urgent need to improve maize salt tolerance and crop yield. In this study, the SsNHX1 gene of Suaeda salsa, which encodes a vacuolar membrane Na~+/H~+ antiporter, was transformed into the maize inbred line 18-599 by Agrobacterium-mediated transformation. Transgenic maize plants overexpressing the SsNHX1 gene showed less growth retardation when treated with an increasing NaCl gradient of up to 1%, indicating enhanced salt tolerance. The improved salt tolerance of transgenic plants was also demonstrated by a significantly elevated seed germination rate(79%) and a reduction in seminal root length inhibition. Moreover, transgenic plants under salt stress exhibited less physiological damage. SsNHX1-overexpressing transgenic maize accumulated more Na~+ and K~+ than wild-type(WT) plants particularly in the leaves, resulting in a higher ratio of K~+/Na~+ in the leaves under salt stress. This result revealed that the improved salt tolerance of SsNHX1-overexpressing transgenic maize plants was likely attributed to SsNHX1-mediated localization of Na~+ to vacuoles and subsequent maintenance of the cytosolic ionic balance. In addition, SsNHX1 overexpression also improved the drought tolerance of the transgenic maize plants, as rehydrated transgenic plants were restored to normal growth while WT plants did not grow normally after dehydration treatment. Therefore, based on our engineering approach, SsNHX1 represents a promising candidate gene for improving the salt and drought tolerance of maize and other crops.

Overexpression of a maize SNF-related protein kinase gene, ZmSnRK2.11, reduces salt and drought tolerance in Arabidopsis

Sucrose non-fermenting-1 related protein kinase 2 （SnRK2） is a unique family of protein kinases associated with abiotic stress signal transduction in plants. In this study, a maize SnRK2 gene ZmSnRK2.11 was cloned and characterized. The results showed that ZmSnRK2.11 is up-regulated by high-salinity and dehydration treatment, and it is expressed mainly in maize mature leaf. Atransient expression assay using onion epidermal cells revealed that ZmSnRK2.11-GFP fusion proteins are localized to both the nucleus and cytoplasm. Overexpressing-ZmSnRK2.11 in Arabidopsis resulted in salt and drought sensitivity phenotypes that exhibited an increased rate of water loss, reduced relative water content, delayed stoma closure, accumulated less free proline content and increased malondialdehyde （MDA） content relative to the phenotypes observed in wild-type （WT） control. Furthermore, overexpression of ZmSnRK2.11 up-regulated the expression of the genes ABI1 and ABI2 and decreased the expression of DREB2A and P5CSI. Taken together, our results suggest that ZmSnRK2.11 is a possible negative regulator involved in the salt and drought stress signal transduction pathways in plants.

Metabolic responses to combined water deficit and salt stress in maize primary roots

Soil water deficit and salt stress are major limiting factors of plant growth and agricultural productivity. The primary root is the first organ to perceive the stress signals for drought and salt stress. In this study, maize plant subjected to drought, salt and combined stresses displayed a significantly reduced primary root length relative to the control plants. GC-MS was used to determine changes in the metabolites of the primary root of maize in response to salt, drought and combined stresses. A total of 86 metabolites were measured, including 29 amino acids and amines, 21 organic acids, four fatty acids, six phosphoric acids, 10 sugars, 10 polyols, and six others. Among these, 53 metabolites with a significant change under different stresses were identified in the primary root, and the content of most metabolites showed down-accumulation. A total of four and 18 metabolites showed significant up-and down-accumulation to all three treatments, respectively. The levels of several compatible solutes, including sugars and polyols, were increased to help maintain the osmotic balance. The levels of metabolites involved in the TCA cycle, including citric acid, ketoglutaric acid, fumaric acid, and malic acid, were reduced in the primary root. The contents of metabolites in the shikimate pathway, such as quinic acid and shikimic acid, were significantly decreased. This study reveals the complex metabolic responses of the primary root to combined drought and salt stresses and extends our understanding of the mechanisms involved in root responses to abiotic tolerance in maize.

Downregulation of the DST Transcription Factor Using Artificial microRNA to Increase Yield, Salt and Drought Tolerance in Rice

Abiotic stresses like salinity and drought directly affect plant growth and water availability, resulting in lower yield in rice. So, a combination of stress tolerance along with enhanced grain yield is a major focus of rice breeding. It was reported earlier that loss in function of the drought and salt tolerance (DST) gene results in increase in grain production through downregulating Gn1a/OsCKX2 expression. Moreover, dst mutants also showed enhanced drought and salt tolerance in rice by regulating genes involved in ROS homeostasis. In the present study, we proceeded to test these reports by downregulating DST using artificial microRNA technology in the commercial but salt sensitive, high-yielding, BRRIdhan 28 (BR28). This cultivar was transformed with DST_artificial microRNA (DST_amiRNA) driven by the constitutive CaMV35S promoter using tissue culture independent Agrobacterium mediated in planta transformation. DST_amiRNA transgenic plants were confirmed by artificial microRNA specific PCR. Transformed plants at T0 generation showed vigorous growth with significantly longer panicle length and higher primary branching resulting in higher yield, compared to the wild type (WT) BR28. Semi-quantitative RT PCR confirmed the decrease in DST expression in the BR28 transgenic plants compared to WT. T1 transgenic plants also showed improvement in a number of physiological parameters and greater growth compared to WT after 14 days of 120 mM salt (NaCl) stress at seedling stage. Therefore, DST downregulated transgenic plants showed both higher stress tolerance as well as better yields. Furthermore, stable inheritance of the improved phenotype of the DST_amiRNA transgenics will be tested in advanced generations.

Overexpression of a sugarcane ScCaM gene negatively regulates salinity and drought stress responses in transgenic Arabidopsis thaliana

Calmodulin(CaM)proteins play a key role in signal transduction under various stresses.In the present study,the effects of a sugarcane ScCaM gene(NCBI accession number:GQ246454)on drought and salt stress tolerance in transgenic Arabidopsis thaliana and Escherichia coli cells were evaluated.The results demonstrated a significant negative role of ScCaM in the drought and salt stress tolerance of transgenic lines of A.thaliana,as indicated by the phenotypes.In addition,the expression of AtP5CS and AtRD29A,two genes tightly related to stress resistance,was significantly lower in the overexpression lines than in the wild type.The growth of E.coli BL21 cells expressing ScCaM showed weaker tolerance under mannitol and NaCl stress.Taken together,this study revealed that the ScCaM gene plays a negative regulatory role in both mannitol and NaCl stresses,and it possibly exerts protective mechanisms common in both prokaryotes and eukaryotes under stress conditions.

Genome-Wide Identification of ALDH Gene Family under Salt and Drought Stress in Phaseolus vulgaris

Background:Aldehyde dehydrogenase(ALDH)genes constitute an important family of supergenes that play key roles in synthesizing various biomolecules and maintaining cellular homeostasis by catalyzing the oxidation of aldehyde products.With climate change increasing the exposure of plants to abiotic stresses such as salt and drought,ALDH genes have been identified as important contributors to stress tolerance.In particular,they help to reduce stress-induced lipid peroxidation.Objectives:This study aims to identify and characterize members of the ALDH supergene family in Phaseolus vulgaris through a genome-wide bioinformatic analysis and investigate their role in response to abiotic stressors such as drought and salt stress.Methods:Genome-wide identification of 26 ALDH genes in P.vulgaris was performed using bioinformatics tools.The identified ALDH proteins were ana-lyzed for molecular weight,amino acid number,and exon number.Phylogenetic analysis was performed to clas-sify P.vulgaris,Arabidopsis thaliana,and Glycine max ALDH proteins into different groups.Strong links between these genes and functions related to growth,development,stress responses,and hormone signaling were identified by cis-element analysis in promoter regions.In silico expression,analysis was performed to assess gene expression levels in different plant tissues.Results:RT-qPCR results showed that the expression of ALDH genes was signif-icantly altered under drought and salt stress in beans.This study provides a comprehensive characterization of the ALDH supergene family in P.vulgaris,highlighting their potential role in abiotic stress tolerance.Conclusion:Thesefindings provide a basis for future research on the functional roles of ALDH genes in enhancing plant resis-tance to environmental stressors.

OsABT,a Rice WD40 Domain-Containing Protein,Is Involved in Abiotic Stress Tolerance

Plant growth and crop productivity are severely affected by abiotic stress on a global scale.WD40 repeat-containing proteins play a significant role in the development and environmental adaptation of eukaryotes.In this study,OsABT,a stress response gene,was cloned from rice(Oryza sativa L.cv.Nipponbare).OsABT encodes a protein containing seven WD40 domains.Expression analysis revealed that the OsABT gene was first up-regulated and then down-regulated following treatment with abscisic acid(ABA)and NaCl,but was down-regulated when treated with PEG8000.Subcellular localization results showed that OsABT was located in the cytoplasm and nucleus of Arabidopsis roots.OsABT transgenic Arabidopsis showed significantly increased tolerance to ABA and salt stress during plant seedling development.However,the transgenic lines were more sensitive to drought stress.Moreover,OsABT can interact with OsABI2,a component of ABA signaling pathway.These results showed that OsABT plays a positive regulatory role in response to salt stress and a negative role in response to drought stress in Arabidopsis.

Genome-Wide Identification and Characterisation of Abiotic Stress Responsive mTERF Gene Family in Amaranthus hypochondriacus

Abiotic stresses at different growth stages in the life of plants negatively affect yield productivity.Therefore,plants,including Amaranthus hypochondriacus,develop adaptive strategies to face the stresses and expand functional diversification.In plants,the mitochondrial transcription termination factors(mTERF)are essential functions in regulation,and organelles(mitochondria and chloroplasts)control gene expression(OGE)under several stress conditions.Based on the in-silico-wide genome and transcriptome analysis,twenty-four mTERF genes were detected in the main targeted mitochondria organelles clustered into three different main groups.The chromosomal location and gene duplication analysis indicated one segmental and one tandem duplication in the genome.The promoter region cis-elements assessment showed that there wasa high correlation between the growth and development process,stress,and hormone responses of these genes.Expression profiling of mTERF genes under salt stress revealed a total number of 24 gene families with seven upregulated and 6 down-regulated genes in drought and salt stress.However,Ah-mTERF-8 and 14 indicated up-regulation under drought stress.Ah-mTERF-4,6,14,15,17,and 20 were up-regulated under salt stress.Molecular characterization and identification through the in-silico study of the specific genes and their differential expression profiling demonstrated the role of mTERF proteins throughout their reaction to growth and development,during stress in A.hypochondriacus.These results demonstrated that mTERF genes were significantly related to the abiotic stress responses.

Expression Analysis of WRKY Transcription Factor Genes in Response to Abiotic Stresses in Horsegram (Macrotyloma uniflorum (Lam.) Verdc.)

Drought and salt stress are two major environmental constraints that limit the productivity of agriculture crops worldwide. WRKY transcription factors are the plant-specific transcription factors that regulate several developmental events and stress responses in plants. The WRKY domain is defined by a 60-amino acid conserved sequence named WRKYGQK at N-terminal and a Zinc Finger-like motif at the C-terminal. WRKY genes are known to respond several stresses which may act as negative or positive regulators. The function of most of the WRKY transcription factors from non-model plants remains poorly understood. This investigation shows the expression levels of eight WRKY transcription factor genes from horsegram plant under drought and salt stress conditions. The increase in mRNA transcript levels of WRKY transcription factor genes was found to be high in drought stressed plants compared to salt-stressed plants. The levels of MDA which indicates the lipid peroxidation were less in drought stress. More ROS is produced in salt stress conditions compared to drought. The results show that the expression of WRKY transcription factors in drought stress conditions is reducing the adverse effect of stress on plants. These results also suggest that, during abiotic stress conditions such as drought and salt stress, WRKY transcription factors are regulated at the transcription level.

亚麻LuWRI1a在旱盐胁迫响应中的功能分析

AP2/ERF转录因子家族参与植物对生物和非生物胁迫响应的调控。前期我们从亚麻中克隆了一个WRINKLED1的同源基因LuWRI1a,蛋白序列分析发现,LuWRI1a包含2个AP2的DNA结合域,属于AP2/ERF转录因子家族。对LuWRI1a的顺式作用元件进行分析发现,pLuWRI1a包含响应光、干旱、低温和激素等多个非生物胁迫应激元件。本研究以亚麻栽培品种陇亚10号和LuWRI1a过表达转基因纯合株系为试验材料,用200 mmol L^(-1)NaCl营养液和25%PEG营养液模拟盐胁迫和干旱胁迫处理。结果表明,在盐胁迫和干旱胁迫处理后,转基因植株的相对株高、主根长度、侧根数目及叶片数均升高;3种抗氧化酶的活性均显著高于对照,而MDA含量低于对照;非生物胁迫响应基因LuAREB、LuDREB、LuLEA和LuNCED的表达水平均上调。通过探究LuWRI1a在逆境胁迫下的生物学功能发现,LuWRI1a通过抵抗盐胁迫和干旱胁迫对亚麻生长的抑制,增强活性氧清除能力、减轻膜脂的氧化损伤,激活逆境胁迫响应基因的表达等途径,增强了亚麻的耐逆性。综上所述,LuWRI1a可能是一个多功能基因,它不仅参与脂肪酸合成代谢途径,还有可能参与植物非生物胁迫信号途径。本研究为亚麻耐逆品种改良提供了新的基因资源。