Mechanism Of Sulfur Regulation On Growth And Glucosinolate Synthesis In Cabbage And Study On The Function Of BoMYC1

Glucosinolate is a significant secondary metabolite in cabbage,which is known as an important antibacterial and anti-cancer substances and plays a momentous role in the health care quality of cabbage.Sulfur is a significant mineral element in the growth and development of cabbage,and it is also an important constituent of glucosinolates.At present,the regulatory mechanism of sulfur on glucosinolates has not yet been elucidated.In this study,using cabbage "Zhonggan 11" as the material,the effects of +S and-S treatments on the growth,glutathione cycle system,sulfur assimilation process and nitrogen assimilation process,photosynthetic system,nutrients and glucosinolates of cabbage were determined.The internal mechanism of sulfur on glucosinolates synthesis pathway was explored from the transcriptome and proteome levels.The regulatory mechanism of target gene Bo MYC1 on glucosinolates synthesis was verified by molecular biological means.The main conclusions of the test are as follows:(1)+S treatment can promote the growth of cabbage.+S treatment significantly boosted the plant height and stem diameter,increased the photosynthetic capacity of the bulb,the activity of the antioxidant system of cabbage,and promoted the glutathione circulation system.ATP sulfurylase(ATPS),APS reductase(APR),sulfite reductase(Si R),serine acetyltransferase(SAT),O-acetylserine thiol lyase(OASTL)increased with the addition of sulfur.Glutamine synthase(GS)and glutamate synthase(GOGAT)were promoted under +S treatment.Therefore,+S can promote the growth and development of cabbage,activate the activities of enzymes related to the sulfur assimilation pathway and nitrogen assimilation pathway,and promote the glutathione cycle,thereby promoting the growth of cabbage and the assimilation of sulfur.(2)+S treatment promoted the accumulation of nutrients and increased the content of polyphenols and glucosinolates in cabbage.+S treatment significantly increased the accumulation of soluble protein,VC,amino acids and other nutrients.The content of flavonoids in the polyphenol components under +S treatment was significantly higher than that under-S treatment,and the contents of protocatechuic acid,gallic acid,4-coumaric acid,sinapic acid and chlorogenic acid in phenolic acids were also increased by +S treatment.+S treatment was significantly higher than-S treatment.There were more glucosinolate components under +S treatment than under-S treatment,and the content of each component of glucosinolate under +S treatment was significantly higher than that under-S treatment.(3)+S treatment modulates glucosinolate biosynthesis through amino acid metabolic pathways,hormone signal transduction,and glucosinolate biosynthesis pathways.1848 differential genes and 95 differential proteins were screened by transcriptome and proteome data analysis.Through GO functional annotation,it was found that the differential genes were significantly enriched in the circadian rhythm in the molecular function entry,the antioxidant activity in the biological process entry,and the extracellular part in the cellular component entry.KEGG enrichment analysis demonstrated that amino acid metabolism pathways and hormone signal transduction were significantly regulated by sulfur.And screened the Bo MYC1 gene as a candidate gene for further research,which can regulate the hormone signal transduction pathway and affect the biosynthesis of glucosinolates.(4)Biological analysis and functional verification of Bo MYC1 transcription factor were performed on members of the MYC gene family in cabbage.A total of 17 members of the Bo MYC gene family of cabbage are mainly located in the nucleus,and they are divided into 3 subgroups with 5-7 members in each family.In the secondary structure of the 17 member proteins,the α-helix ranged from 32.6% to46.45%,and the random coil ranged from 38% to 52.32%.At the same time,the expression of this family member in different tissues was specific.Among them,the Bo MYC1 transcription factor was expressed in leaves and the highest expression level was found in fruit.KEGG analysis elucidated that Bo MYC has a regulatory effect on hormone signal transduction,and the Bo MYC1 was significantly up-regulated when IAA,ABA and GA were treated for 24 h.The Bo MYC1 was significantly up-regulated when Me JA were treated for 48 h.Therefore,combined with the results of transcriptome and proteome analysis,the Bo MYC1 gene was selected for cloning,and the gene transient expression,gene silencing and overexpression vectors were constructed.Through Agrobacterium-mediated cabbage leaves and inflorescence infection of Arabidopsis thaliana,the transient expression vector was injected into cabbage leaves The GLS content was significantly increased;the GLS content in cabbage leaves injected with gene silencing vector was significantly decreased;the GLS content in transgenic Arabidopsis was significantly increased.Subcellular localization of tobacco leaves found that the Bo MYC1 gene was located in the nucleus,which was consistent with the predicted results of bioinformatics.