The Mutual Regulation Between NAC Transcription Factors And The Genes Related To Ethylene Biosynthesis And Signal Transduction

NAC transcription factor is regarded as a plant-specific transcription factor with varies of biological control functions.Studies report that NAC transcription factors are involved in regulating the plant growth,hormone signal transduction process and stress response.This research used bioinformatics method to predict the structure and biological function of SNAC4-9 transcription factors in tomato.The role of NAC in regulating fruit ripening and ethylene sinaling was further studied by application of VIGS method to silence the NAC and ethylene synthesis and signal transduction related genes.(1)Bioinformatics analysis.The senior structure and biological function of SNAC4-9 was predicted,the results exhibited that SNAC4 and SNAC6 were best match with ANAC072;SNAC5 and SNAC8 were best match with ANAC072;SNAC7 and SNAC9 were best match with ANAC029 and they processed the similar senior structure.The results of biofunction prediction revealed that SNAC4-9 were possible to regulate the signal transduction of auxin,Abscisic acid and jasmonic acid.The results of prediction about the transcription factor binding sites in promoter sequences of ethylene synthesis and signal transduction related genes Le ACS4,Le ACO1,NR,Le ETR4,Le CTR1,Le ERF2 revealed that ethylene related factors might be involved in regulation of jasmonic acid,abscisic acid and salicylic acid hormone response and stress response such as high temperature,drought and so on.(2)VIGS research analysis.p TRV2-Le ACS4/Le ACO1/NR/Le ETR4/Le CTR1/Le ERF2 vectors were successfully constructed.10 days after agrobacterium infection,height of SNACs-silenced plants was shorter than the control tomato.All the SNACs-silenced and ethylene related genes-silenced fruits exhibited mature delayed phenotypes,whereas the control fruit got ripen as usual.(3)The results of transcription level test of gene silenced tomato indicated that silence of SNACs genes affected the expression level of ethylene synthesis and signal transduction related gene.Allover,decrease of SNAC expression level inhibited the transcription of ethylene synthesis genes Le ACS2,Le ACS4,Le ACO1 and ethylene receptor genes NR and Le ETR4.In addition,the expressions of SNACs were also influenced by the condition of transcription of ethylene synthesis and transduction related genes.The silencing of ethylene synthesis genes Le ACS4/Le ACO1,and code gene of ethylene transduction-related element Le CTR1/ Le ERF2 repressed the expression of SNACs,however the silencing of ethylene reception genes NR/Le ETR4 induced SNACs expression.(4)SNAC4 suppression reduced the ethylene release rate of tomato fruit during the ripening process and the delayed the occurrence of climacteric ethylene peak.