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Transcriptional And Metabolic Analysis Of Anthocyanin Synthesis Regulated By Blue Light In Postharvest Purple Sweet Pepper

Posted on:2022-12-17Degree:MasterType:Thesis
Country:ChinaCandidate:X T WangFull Text:PDF
GTID:2493306749998229Subject:Automation Technology
Abstract/Summary:PDF Full Text Request
Sweet pepper(Capsicum annuum L.)is one of the most important horticultural crops in China.It is widely loved by consumers for its rich nutrients and medicinal value.Light,especially light quality,is an important environmental factor affecting the biosynthesis of plant anthocyanins.Studies have shown that blue light plays a crucial role in plant anthocyanin biosynthesis.However,the regulatory effect of blue light on anthocyanin biosynthesis pathway in postharvest fruit of purple sweet pepper and its underlying molecular mechanism is still unclear.Therefore,in this study,the anthocyanin-rich purple sweet pepper variety ‘Amethyst’ was used as the test material to investigate the effects of blue and white light on the composition and content of anthocyanin as well as the expression of genes related to anthocyanin synthesis in postharvest sweet pepper fruit at different ripening stages.We found the ripening stage when anthocyanins and their key synthesis genes respond significantly to blue light,and conducted transcriptome analysis of the postharvest sweet pepper fruit of colored at the corresponding ripening stage.Then,the transcription factors that regulate blue light-induced anthocyanin biosynthesis in postharvest fruit of purple sweet pepper were screened.The main results are as follows:1.At different ripening stages of sweet pepper,the fruit chromaticity was significantly different,which was green at the young fruit stage,purple at the green ripening and color turning stage,and red at the mature stage.The chlorophyll content of purple sweet pepper gradually decreased,and the carotenoid content gradually increased,while the anthocyanin content enhanced firstly and then reduced,and reached the maximum level at green ripening stage.Moreover,during this ripening stage,compared with white light,the anthocyanin content in sweet pepper fruit treated with blue light for 24 h was significantly raised,but there was no significant difference in fruit chromaticity.2.At different ripening stages,the key genes involved in anthocyanin synthesis in postharvest fruit of purple sweet pepper were flavanone-3-hydroxylase(Ca F3H),flavanone-3′,5′-hydroxylase(Ca F3’5’H)and UDP-glucose flavonoid 3-O-glucosyltransferase(Ca UFGT)were similar to the pattern of anthocyanin accumulation,and these genes were all significantly up-regulated at green ripening stage.In addition,the expression of anthocyanin biosynthesis-related structural genes in postharvest fruit of purple sweet pepper treated with blue light for 4 h were significantly up-regulated compared with white light at this stage.3.The anthocyanin-targeted metabolome analysis was performed on postharvest fruits of purple sweet pepper treated with blue light for 24 h at different ripening stages.The results showed that 20 kinds of anthocyanins were detected in the fruit.Among them,trihydroxy anthocyanins were the main ones,and only a small amount of dihydroxy anthocyanins were detected.Compared with white light,blue light could significantly increase the levels of delphinin-3-O-glucoside,delphinin-3-O-rrnoside and delphinin-3-O-rutin in sweet pepper at green ripening stage,which was related to the specific high expression of anthocyanin biosynthesis structure genes,including Ca F3’5’H and Ca UFGT.4.Transcriptome analysis was performed after blue light treatment after 0,2 and 4 h of postharvest fruit of purple sweet pepper at green ripening stage.The results showed that compared with 0 h,a total of 2052 and 3276 differential genes were detected at 2 h and 4 h,respectively.GO functional annotation of differential genes revealed that a large number of differential genes were annotated in metabolic process,stress response,transporter activity and transcriptional regulation activity.KEGG cluster analysis was performed on the differential genes,and it was found that a large number of differential genes were enriched in the biosynthesis of secondary metabolites and plant circadian rhythm pathways.We obtained6 structural genes and 12 transcription factors related to anthocyanin biosynthesis in postharvest fruit of purple sweet pepper in response to blue light by screening.Among them,the expression of CaMYB1R1 under blue light was significantly higher than that under white light.Through bioinformatics analysis of CaMYB1R1,it was found that the promoter region of this transcription factor contains g-box and other binding sites.Therefore,it is speculated that CaMYB1R1 may regulate blue light-induced anthocyanin biosynthesis in postharvest fruit of purple sweet pepper.
Keywords/Search Tags:Blue Light, Sweet Pepper, Anthocyanin, Transcription Factor
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