Functional Analysis Of GhABF1 In Cotton In Responsive To Drought Stress

Cotton is considered as a crucial commercial crop as well as a raw material for textile industry.In spite of being resistance to environmental stresses,the production and quality of cotton are being dropping because cultivated land are contracting which transferred cotton from favorable environmental conditions to unfavorable land facing salinity and drought.In this regard,growing of resistant varieties of cotton to abiotic stresses are helpful to agricultural growth and social stability.To exploit cotton genome sequencing,molecular breeding and genetic engineering experiments can be carried out for cotton.The basic leucine zipper(b ZIP)transcription factor is one of the largest transcription factors which can be divided into 13 groups,among them group A is closely related to stress response.In recent years,the b ZIP transcription factors has been shown to be involved in stress response,so we need to explore the mechanism of this signal transduction.The normalized cDNA library from sea-land cotton was used to isolate GhABF1,a b ZIP transcription factor,explored and identified its functional role and mechanism in response to environmental stresses in cotton.The key results we found are listed below:1.Analysis of a normalized multiple stress treatments cDNA libraryA normalized cDNA library was constructed using Gossypium barbadense Hai-7124 treated with different stress conditions(heat,cold,salt,drought,potassium and phosphorus deficit and Verticillium dahliae infection).Random sequencing of this library generated 6,047 high-quality expressed sequence tags(ESTs).The ESTs were clustered and assembled into 3,135 uni ESTs,composed of 2,497 contigs and 638 singletons.The blastx results demonstrated 2,746 unigenes showing significant similarity to known genes,74 uni ESTs displaying significant similarity to genes of predicted proteins,and 315 uni ESTs still uncharacterized.Functional classification unveiled the abundance of uni ESTs in binding,catalytic activity,and structural molecule activity.Annotations of the uni ESTs by the plant transcription factor database(Plant TFDB)and Plant Stress Protein Database(PSPDB)disclosed that transcription factors and stress-related genes were enriched in the current library.The expression of some transcription factors and specific stress-related genes were verified by RT-PCR under various stress conditions.2.Functional analysis of GhABF1 during drought stress in cottonBased on the cDNA library,GhABF1 was screened study its function in cotton in response to drought stress.GhABF1 has two typical domains of b ZIP transcription factors,and it was most homogeneous to Gr ABI5.Promoter sequence analysis of the GhABF1 revealed that it had some cis-acting elements responsive to abscisic acid,jasmonic acid,ethylene and gibberellin responsive elements,anaerobic induction,heat stress and other defense response components.Meanwhile,cell cycle and endosperm expression responsive elements were also found.The expression of GhABF1 was significantly up-regulated by ABA,PEG and Na Cl treatments.Virus Induced Gene Silencing(VIGS)were used to silence GhABF1 in cotton.leaf water loss assays and leaf disc assays indicated that VIGS silencing of Gh NAC3 enhanced the the tolerance to drought and salt in cotton.At the same time,we used GhABF1 as a bait to filter cotton abiotic stress library by Y2 H system,and 12 proteins were select as interact with GhABF1.The point-to-point hybrids further validated that the G protein coupled receptor Gh GCR2(Gh_D01G0507)interact with GhABF1 in an unknown manner to regulate gene expression.However,further evidence needed to clarify molecar mechanism of GhABF1 in regulating cotton in response to stress treatment.