Studying Of The Molecular Mechanisms Of AtNSOS1 And AtHAB3 Genes Regulating Stress Response In Arabidopsis Thaliana

Environmental stresses are major factors affecting the growth and development of plants during the whole life cycle besides their own genome or genotype.In northwest China,drought,saline and cold stress are main environmental factors that effect the yield of crops.Abscisic acid(ABA)accumulates under such stress conditions in plant cells,and therefore it is a key phytohormone in studying of plant reponses to abiotic stress.NAC transcription factor(TF)gene family is plant-specific and,their coded proteins usually harbor a conserved NAC domain at its N-terminus.Studies have demonstrated that members of NAC family participate in plant growth,development,stress response and tolerance,possibly through positively or negatively regulating stress-related genes’ expression.Several members in protein phosphatase 2C(PP2C)family have also been identified to paly a role in signaling pathways of ABA and osmotic stress.PP2C could antagonize kinases like sucrose non-fermentating related kinase(SnRK)and thus may negatively modulate physiological processes.Although both NAC and PP2C families have been well studied in Arabidopsis thalian,the function of many members are not known yet.In this study,we identified AtNSOS1 as a NAC transcription factor and AtHAB3 as a PP2C,which participate in abiotic stress responses.Therefore we designed a series of experiments to study their function in plants.As a result,we found AtNSOS1 regulates plant responses to salt and heat stress at the transcriptional level.Phenotypic analysis of nsosl mutant showed it modulated salt and heat stresss and also,nsosl is highly sensitivity to ABA,which demonstrates that AtNSOS1 may function in the cross-talk of salt,cold and ABA signaling pathways.AtHAB3 was identified to negatively regulate ABA reponse and,yeast-two-hybrid(Y2H)and bimolecular fluorescence complementation(BiFC)also supported that A tHAB3 participated in ABA signaling pathway.Besides,in the present study,we cloned cDNA sequences of part of NAC genes in canola(Bi-assica napus L.).Through quantitative RT-PCR,transcriptional activity assay in yeast,subcellular localization determination using green fluorescence protein(GFP)as a marker,as well as programmed cell death(PCD)analysis,we identified several of canola NAC genes regulated abiotic stress and/or hormone response and,two novel NAC regulating PCD.