Functional Analysis Of GhNAC3 In Cotton In Responsive To Abiotic Stress

Abiotic stresses affect the growth,development,yield and fiber quality of cotton seriously.It is of great importance to creat drought and salt resistant cotton.NAC(NAM,ATAF1 / 2,CUC2)is a kind of plant-specific transcription factor,which is widely involved in the response to abiotic stresses.In this study,a NAC gene,GhNAC3 was isolated from the expression profile of drought stress treatment in cotton,and the functions of GhNAC3 in cotton in response to drought and salt stresses were chracterized.The main results were as follows:232 NAC transcription factor genes were idenified,and their tissue expression patterns and abiotic stresses induced expression profiles were analyzed in cotton.Meanwhile,GhNAC3 gene was cloned from upland cotton.Sequence analysis showed that GhNAC3 had a conserved NAC domain.The subcellular localization assay indicated that GhNAC3 encoded a nuclear protein.The transactivation assay in yeast revealed that the GhNAC3 BD domain(1-160aa)didn't have the function of transcriptional activation,but the AD domain(161-298aa)had the function of transcriptional activation.GhNAC3 was found to predominantly express in roots and flowers.And its expression was significantly up-regulated by PEG and NaCl treatments.In addition,promoter sequence analysis of the GhNAC3 revealed that it had some cis-acting elements responsive to drought,salt and ABA,such as ERD1(early reactions to dehydration)and DRE / CRT(dehydration-responsive element / C-repeat).The overexpression vector of GhNAC3 was transformed to Arabidopsis,and the homozygous transgenic lines were used for further investigation.Germination and growth experiments showed that overexpression of GhNAC3 could enhance the tolerance to osmotic stress and salt stresses,and decrease the sensitivity to ABA in Arabidopsis thaliana.ABA content was reduced in GhNAC3 VIGS silencing cotton plants,while hydrogen peroxide(H2O2)and malondialdehyde(MDA)content were accumulated in the interference material under drought treatment.Moreover,leaf water loss assays,natural drought stress experiments and leaf disc assays indicated that VIGS silencing of GhNAC3 reduced the the tolerance to drought and salt in cotton.Moreover,we also obtained the overexpression transgenic cotton lines.Overexpression lines,negative separation line and wild-type were treated by PEG6000 in water.The results showed that the overexpression lines exhibited better growth potential than the control materials.The above results indicated that GhNAC3 might involve in the regulation of abiotic stress response in cotton.We speculated that the gene might involve in the response to drought and salt stress by mediating ABA signaling This research will provied gene material and molecular basis for stress resistant breeding in cotton.