The Impact Of GhNAC82/62 Transcription Factors In Leaf Senescence In Upland Cotton(Gossypium Hirsutum L.)

In the process of growth and development,cotton appears premature senescence under various biotic or abiotic stresses,which seriously affects the yields and quality of cotton fiber.NAC transcription factors are a large family of plant-specific transcription factors,which play a key role in regulating plant responsed to abiotic stress.Stress regulation is often related with through the level of endogenous hormones,and the responses of hormones and stress response are inseparable.In this study,Gh NAC82 and Gh NAC62 of NAC family were identified and analyzed in upland cotton.The main results as follows:（1）The spatio-temporal expression pattern was analyzed by GEO database（cotton transcriptome）and verified by fluorescence quantification.It was found that the trend of transcriptome was consistent with fluorescence quantitative data.Gh NAC82 gene plays an important regulatory role in ovule,while Gh NAC62 gene may play a major role in root.（2）Analysis of the expression profile under salt,drought stress and hormone induction revealed that Gh NAC82 responded quickly to drought stress and continued throughout the treatment process,and responded slowly to salt stress.The expression level was highest at 15 days after treatment,and then decreased Gh NAC82 was sensitive and responds most rapidly after Me JA treatment in premature cotton.And Gh NAC82 can continuously responded to H₂O₂stress.Gh NAC62 responded slowly to salt and drought stress.The expression level was highest at 15 days after treatment,then continued to decline,which was similar to Gh NAC82.After different hormone treatments,Gh NAC62 had no obvious change pattern,but it responded most quickly to H₂O₂.（3）After analyzing the data of overring expression of Gh NAC82 and Gh NAC62 in Arabidopsis thaliana,it was found that overexpression of two genes could lead to premature senescence of Arabidopsis thaliana.And plant height was increase after silencing Gh NAC82 and Gh NAC62 by VIGS in contton,respectively.Through the above analysis of Gh NAC82 and Gh NAC62 genes,we found out that Gh NAC82 and Gh NAC62 were involved in different leaf stress senescence pathways:overexpression could promote senescence,while silence could delay senescence in cotton.