Genome Wide Analysis And Functional Characterization Of GPCR And MATE Gene Families Under Abiotic Stress In Cotton

1.Plants have developed number of survival strategies which are significant for enhancing their adaptation to various biotic and abiotic stress factors.At transcriptome level,G-protein coupled receptors?GPCRs?are of significant,enables the plants to detect a wide range of endogenous and exogenous signals,which are employed by the plants in regulating various responses in development and adaptation.In this research work,we carried out functional characterization of a novel gene member of the cotton GPCR,through transformation into the model plant,Arabidopsis thaliana,ecotype Colombia-0,further profiled the cloned gene under salt stress condition.By the use of the functional domain,PF06454,a total of 36 GPCR genes in the three sequenced cotton species,in the proportion of16,9 and 11 genes members in Gossypium hirsutum,Gossypium arboreum and Gossypium raimondii,respectively.Although the proteins encoding the GPCR genes had varied physiochemical properties,all the grand average hydropathy?GRAVY?values of proteins were more than 0,which indicated that all were hydrophobic in nature.Moreover,all the cotton GPCR genes contained introns.The expression level of the novel gene,Gh_A07G0747?GhTOM?was significantly high in the transgenic lines as compared to the wild type Arabidopsis;similar trend was also observed among the salt responsive genes.The protein encoding the novel gene found to be localised in the plasma membrane.Analysis of anti-oxidant enzymes showed higher activities of antioxidants in transgenic lines and relatively lower levels of oxidant substances such as H₂O₂.The MDA content levels indicated that the transgenic lines had a significant reduction level of oxidative damage compared to the wild types Arabidopsis under salt stress conditions.The results obtained indicates that the novel gene,Gh_A07G0747?GhTOM?may be a putative target gene for enhancing salt stress tolerance in cotton,and provide a good research foundation for salt tolerance mechanism and variety improvement for cotton.2.Abiotic stresses have negative effects on plants growth and development.Plants,being sessile,have developed specific adaptive mechanisms that allow them to rapidly detect and respond to abiotic stress factors.Among the evolutionary conserved mechanisms adopted by the plants to minimize the effects of abiotic stress,is through the induction of transcription factors.The abscisic acid?ABA?,a phytohormone with profound role in plants under various abiotic stress conditions,with signaling cascades are the core regulator of abiotic stress response in plants,triggering major changes in gene expression and adaptive physiological responses.The detoxification efflux carriers?DTX?/multidrug and toxic compound extrusion?MATE?transporters are of significance in the translocation of ABA.We therefore carried out genome-wide analysis of the DTX/MATE gene family,transformed a DTX/MATE gene in Arabidopsis and carried out functional analysis under salt,drought and cold stress conditions.We identified 128,70 and 72 DTX/MATE genes in Gossypium hirsutum,Gossypium arboreum and Gossypium raimondii,respectively.The genes showed varied physiochemical properties,while the proteins encoded by the DTX/MATE genes were hydrophobic.The Gh_D06G0281?DTX/MATE?transgenic lines of the gene were highly tolerant under salt,drought and cold stress with high activities of antioxidant enzymes and significantly reduced contents of oxidants.Lipid peroxidation is measured by the level of MDA contents in the leaves;the transgenic plants exhibited relatively low contents compared to wild types Arabidopsis,an indication of reduced oxidative stress levels in the transgenic plants.Based on the physiological measurements,the transgenic plants exhibited significantly higher relative leaf water content,reduced excised leaf water loss and a significant reduction in ion leakage as a measure of the cell membrane stability compared to the wild types.The expression levels of abiotic stress responsive genes,AtABF4,AtCBL1,AtSOS1 and AtRD29B were highly expressed in the transgenic lines compared to the the wild type.The protein encoded by the gene was found to be located within the plasma membrane.The signals from extracellular stimuli are transmitted through the plasma membrane most of which are conducted by plasma membrane proteins in which the Gh_D06G0281?DTX/MATE?gene could be a major player.