Inheritance And Regulation Mechanism Of Pepper Fruit Color Traits

Fruit color is one of the important commercial traits of pepper crops.The formation of pepper fruit color is closely related to the metabolism of chlorophyll,carotenoids and anthocyanins in the fruit.In this study,the mature fruit color orange mutant and wild type were used as materials to study the localization of mutation-related genes,clone genes related to carotenoid biosynthesist,analyse the comparative transcriptomics of different pepper fruit colors and the regulation of carotenoid biosynthesis.Transcriptome and metabolome studies were carried out using light green mutant and dark green wild type of immature peppers as test materials.Preliminary explanation of the molecular regulation mechanism of pepper fruit color formation.The result shows:1.The orange trait of ripe fruit color in Capsicum annuum was controlled by a pair of recessive genes,and H0809 was a recessive mutation of red wild-type XHB.The gene YFC that control pepper fruit color was located between SNP62331595-SNP623324 markers on the Chr06 with a genetic distance within 4.0 c M.The localization region contains CCS gene,there was no differencein the coding region sequence and promoter sequence of CCS gene between the mutant and the wild type,but the expression difference of CCS gene is significant.2.The full-length CCS gene sequence could not be amplified in the yellow mutant SP02 and the orange mutant PC02,indicating that the formation of the fruit color of the SP02 and PC02 mutants may be related to the deletion or variation of the CCS gene.The full-length sequences of GGPS,PSY,LCYB,CRTZ,ZEP and CCS genes can be expanded in red wild-type XHB,SP01,PC01 and orange mutant H0809.However,in H0809,the expression of CCS gene remained at a low level in different developmental stages of fruit color,indicating that the formation of H0809 mutant fruit color may be related to the different expression regulation modes of CCS gene.3.Comparative transcriptomic analysis of red wild-type XHB and orange mutant H0809 fruit color at different developmental stages showed that BCH and CCS genes were differentially expressed at 25 d,40 d and 55 d after flowering;transcription factors F-box,GATA,U-box,FYVE/PHD-type,RING/FYVE/PHD-type,NAC and Auxin gene family related genes may be involved in the regulation of CCS genes.4.The NAC transcription factor Ca NAC06 and the auxin gene Ca IAA09 bind to the promoters of CCS,BCH,LCYB and PSY genes,and Ca NAC06 and Ca IAA09 also have binding activity in vitro.Overexpression of Ca NAC06 significantly increased chlorophyll and carotenoid content and carotenoid related gene expression in Arabidopsis leaves.After silencing Ca NAC06 and Ca IAA09 genes in isolated fruits,the expressions of CCS,LCYB and BCH genes were generally down-regulated.It was confirmed that Ca NAC06 and Ca IAA09 genes are involved in the regulation of carotenoid biosynthesis in pepper fruit.5.The inheritance of dark green(XHB)and light green mutation(QL2017)in line pepper conforms to the quality traits controlled by a single gene,and dark green was dominant to light green.Transcriptome and metabolome analysis results of different green and ripe fruit colors showed that the differential expression of key enzyme genes and the differential accumulation of metabolites in pathways such as Photosynthesis-antenna proteins,Plant hormone signal transduction,Porphyrin and chlorophyll metabolic pathways,isoflavonoid biosynthesis and anthocyanin biosynthesis were closely related to the formation of different green and ripe fruit colors.