Analysis on Maize EST Database under the Co-stress of Drought,Salt and Alkali

[Objective] The research aimed to construct maize cDNA library under the co-stress of drought,salt and alkali,and initially analyze the expression of gene which related to the cellular function.[Method] The total RNA of mixed tissue（leaf,stem and blossom bud） of maize YQ7-96 in the male and female differentiation period（12-leaf age） was extracted.By using SMART technology,cDNA library of pDNR-LIB vector was constructed.BlastX contrast and MIPS classification analysis of EST sequence were carried out by randomly picking the clone.[Result] 3 027 cDNA clones were picked out to sequence.The length of 94.45% EST was bigger than 400 bp,and 1 861 single gene clusters were obtained.The gene which maintained the normal physiological activity occupied 65.36%.The genes which involved in the intracellular transportation,signal transduction,cell defense and cycle,DNA metabolic process were respectively 9.26%,6.58%,2.63% and 3.16%.[Conclusion] Based on the successful construction of maize cDNA library under the co-stress of drought,salt and alkali,EST was sequenced,analyzed and classified.EST which related to the cellular function was screened.It laid the foundation for the following research.

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.

Function of the auxin-responsive gene TaSAUR75 under salt and drought stress

Small auxin-upregulated RNAs(SAURs) are genes regulated by auxin and environmental factors. In this study, we identified a SAUR gene in wheat, Ta SAUR75. Under salt stress,Ta SAUR75 is downregulated in wheat roots. Subcellular localization revealed that Ta SAUR75 was localized in both the cytoplasm and nucleus. Overexpression of Ta SAUR75 increased drought and salt tolerance in Arabidopsis. Transgenic lines showed higher root length and survival rate and higher expression of some stress-responsive genes than control plants under salt and drought stress. Less H_2O_2 accumulated in transgenic lines than in control plants under drought stress. Our findings reveal a positive regulatory role of the auxin-responsive gene Ta SAUR75 in plant responses to drought and salt stress and provide a candidate gene for improvement of abiotic stress tolerance in crop breeding.

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.

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.

The osmolyte-producing endophyte Streptomyces albidoflavus OsiLf-2 induces drought and salt tolerance in rice via a multi-level mechanism

Drought and salinity are major environmental stresses that impair crop growth and productivity worldwide. Improving drought and salt tolerance of crops with microbial mutualists is an effective and environmentally sound strategy to meet the demands of the ever-growing world population. In the present study, we found that the Streptomyces albidoflavus Osi Lf-2, a moderately salt-tolerant endophytic actinomycete, produced abundant osmolytes, including proline, polysaccharides, and ectoine. Inoculation with Osi Lf-2 increased the osmotic-adjustment ability of the rice host by increasing the proline content(by250.3% and 49.4%) and soluble sugar(by 20.9% and 49.4%) in rice under drought and salt conditions, relative to the uninoculated control. Osi Lf-2 increased stress responses in the rice host at the physiological and biochemical levels(photosynthesis efficiency, osmolytes and antioxidant content), and the gene level(osmolytes synthesis, stress-responsive and ion-transport related genes), raising rice yields under both greenhouse and saline–alkaline soil conditions. The use of endophytic actinomycetes offers a promising biotechnological approach to developing stress-tolerant plants.

Genetic Engineering Peanut for Higher Drought- and Salt-Tolerance

Peanut (Arachis hypogaea L.) is one of the major oilseed crops, mainly grown in tropical and sub-tropical regions of the world. It is also rich in proteins, vitamins and ions, therefore it constitutes an important portion of food nutrition for people in these regions. The production of peanut is being threatened by the changing environments as the major peanut producing counties such as China, India, and USA are facing severe water shortage for peanut irrigation. The yield and quality of peanut are negatively affected by drought and salinity. Making peanut more droughtand salt-tolerant will likely sustain peanut production in countries where water shortage or saline soil are already problems. Efforts were made to genetically engineer peanut for higher tolerance to drought and salt. Analysis of these transgenic peanut plants indicated that the agronomic traits such as peanut yields were the same between wild-type and transgenic peanut plants under normal growth conditions, yet the yields of transgenic peanut plants were much higher than wild-type peanut plant under reduced irrigation conditions. Other traits such as protein content and fatty acid compositions in the seeds of transgenic peanut plants were not altered under both normal and drought conditions, indicating that the genetic manipulation of peanut for stress tolerance did not affect chemical compositions of peanut seeds in transgenic peanut plants, only increased seed yields under stress conditions.

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.

Selection efficiencies for improving drought/salt tolerances and yield using introgression breeding in rice(Oryza sativa L.)

The backcross(BC) breeding strategy has been increasingly used for developing high yielding varieties with improved abiotic stress tolerances in rice. In this study, 189Huang-Hua-Zhan(HHZ) introgression lines(ILs) developed from three different selection schemes were evaluated for yield related traits under drought stress and non-stress conditions in the target and off-season winter nursery environments to assess the selection efficiency of BC breeding for improving different complex traits, and led us to five important results. The first result indicated that the primary target traits should be selected first in the target environments(TEs) in order to achieve the maximum genetic gain. Secondly, BC breeding for drought tolerance(DT) in rice was almost equally effective by strong phenotypic selection in the main target environments and in the winter-season of Hainan.Thirdly, exploiting genetic diversity in the subspecific gene pools is of great importance for future genetic improvement of complex traits in rice. Fourthly, considerable genetic gain can be effectively achieved by selection for secondary target traits among the ILs with the primary traits. Finally, the developed ILs provide useful materials for future genetic/genomic dissection and molecular breeding of complex traits.

OsMas1,a novel maspardin protein gene,confers tolerance to salt and drought stresses by regulating ABA signaling in rice

Drought and salt stresses,the major environmental abiotic stresses in agriculture worldwide,affect plant growth,crop productivity,and quality.Therefore,developing crops with higher drought and salt tolerance is highly desirable.This study reported the isolation,biological function,and molecular characterization of a novel maspardin gene,OsMas1,from rice.The OsMas1 protein was localized to the cytoplasm.The expression levels of OsMas1 were up-regulated under mannitol,PEG6000,NaCl,and abscisic acid(ABA) treatments in rice.The OsMas1 gene was introduced into the rice cultivar Zhonghua 11(wild type,WT).OsMas1-overexpression(OsMas1-OE) plants exhibited significantly enhanced salt and drought tolerance;in contrast,OsMas1-interference(OsMas1-RNAi) plants exhibited decreased tolerance to salt and drought stresses,compared with WT.OsMas1-OE plants exhibited enhanced hypersensitivity,while OsMas1-RNAi plants showed less sensitivity to exogenous ABA treatment at both germination and post-germination stages.ABA,proline and K+ contents and superoxide dismutase(SOD),catalase(CAT),peroxidase(POD),and photosynthesis activities were significantly increased.In contrast,malonaldehyde(MDA),hydrogen peroxide(H2O2),superoxide anion radical(O2-··),and Na+ contents were significantly decreased in OsMas1-OE plants compared with OsMas1-RNAi and WT plants.Overexpression of OsMas1 up-regulated the genes involved in ABA signaling,proline biosynthesis,reactive oxygen species(ROS)-scavenging system,photosynthesis,and ion transport under salt and drought stresses.Our results indicate that the OsMas1 gene improves salt and drought tolerance in rice,which may serve as a candidate gene for enhancing crop resistance to abiotic stresses.

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.

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.

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.

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.

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.

Maize ABP2 enhances tolerance to drought and salt stress in transgenic Arabidopsis

Abiotic stresses, especially drought and salt, severely affect maize production, which is one of the most important cereal crops in the world. Breeding stress-tolerant maize through biotechnology is urgently needed to maintain maize production. Therefore, it is important to identify new genes that can enhance both drought and salt stress tolerance for molecular breeding. In this study, we identified a maize ABA （abscisic acid）-responsive element （ABRE） binding protein from a 17-day post-pollination （dpp） maize embryo cDNA library by yeast one-hybrid screen using the ABRE2 sequence of the maize Cat1 gene as bait. This protein, designated, ABRE binding protein 2 （ABP2）, belongs to the bZIP transcription factor family. Endogenous expression of ABP2 in maize can be detected in different tissues at various development stages, and can be induced by drought, salt, reactive oxygen species （ROS）-generating agents, and ABA treatment. Constitutive expression of ABP2 in transgenic Arabidopsis plants enhanced tolerance to drought and salt stress, and increased sensitivity to ABA. In exploring the mechanism by which ABP2 can stimulate abiotic stress tolerance, we found that ROS levels were reduced and expression of stress-responsive and carbon metabolism-related genes was enhanced by constitutive ABP2 expression in transgenic plants. In Short, we identified a maize bZIP transcription factor which can enhance both drought and salt tolerance of plants.

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.

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.