Preliminary Study On The Molecular Mechanism Of The Gossypium Pigment Gland Formation Gene GoPGF

Cotton is the most important economic crops of fiber in the world,which may also produce protein and oil.Pigment gland and gossypol is one of the most important traits of cotton,it is of great significance for pests and diseases defense of cotton,but the protein and oil content of cottonseed is inedible because of its toxicity.Cotton gland forming gene?Gossypium pigment gland formation,GoPGF?is an important gene of gland formation in cotton plant and seed,Virus induced gene silencing?VIGS?showed that inhibition of GoPGF gene can lead to the abnormal formation of glands.However,the molecular mechanism of this gene is not clear.In order to study the molecular mechanism of GoPGF gene,reveal the internal molecular relationship and construct a regulatory network between gland formation and gossypol biosynthesis.We analyzed the sequence of GoPGF gene in some cotton materials of different gland traits,identified the interaction proteins by yeast two hybrid and CoIP,and transgenic verification etc.to explore the molecular mechanism in controlling cotton gland formation and search the physiological and biochemical processes involved in the metabolic pathway,and provide some references for low gossypol cotton breeding.We draw the following conclusions through this study.1.Based on the analysis of the GoPGF amino acid sequences in different cotton varieties we found that:the A subgroup encodes a serine?S?In the 282nd position of the amino acid encoded by the GoPGF gene of the glandular tetraploid cotton?AADD?;The 380th position was changed to threonine?T?in the cotton which has a low content of gossypol in the pigment gland?EE?;The 376th position was changed to Serine?S?in the cotton whose plant has pigment gland but seeds do not and the cotyledon pigment gland formation was delayed?GG,CC?.From "Seeds have no glands nor gossypol" to "Seeds have glands but no gossypol" to "Seeds have glands and gossypol",We think this is a process of continuous evolution of the glands and gossypol in cotton,and we initially concluded that this diversity was due to the difference of one amino acid locus in the coding sequence of the GoPGF gene.2.We screened the possible interaction proteins of GoPGF through yeast two hybrid and CoIP and found these proteins include five categories:photosynthesis;carbohydrate metabolism and ATP synthesis;metabolism;signal transduction;catalysis and stress and hormone synthesis.3.We transferred GoPGF into Arabidopsis mutants SALK₀40500 and SALK₀83483?they are both the T-DNA insertion mutants,the biological process of terpenoid synthesis which the transcription factor MYC2 involved in is blocked.Therefore,the content of terpenoids is significantly lower than that of wild type?.These genes were up-regulated after the GoPGF gene was transfered in the two Arabidopsis materials:cell wall and cell wall proteins;secondary metabolism;hormone metabolism;regulation of transcription;signalling etc.We analysed the regulation of light signal,ethylene,gibberellin,and jasmonic acid emphatically and speculate the effect of GoPGF on sesquiterpene synthesis defective Arabidopsis at the transcriptional level.After preliminary analysis,we learned that GoPGF transgene leads to the upregulation of genes of stimulating response and biosynthesis to gibberellin and jasmonic acid.On the one hand,the biosynthesis of jasmonic acid can directly lead to the expression of defense genes in the jasmonic acid ethylene signaling pathway,on the other hand,stimulating response genes of gibberellin and jasmonic acid may expressed under the stimulation of the corresponding endogenous hormones to regulate the synthesis of some secondary metabolites of plants.