QTL Mapping Of Vc Content In Pepper Fruit And Genetic Analysis

Pepper(Capsicum spp.),also called chili,Haijiao,spicy,spicy eggplant,etc.,belong to the nightshade family(Solanaceae),genus Capsicum(Capsicum L.),is an important vegetable crop,is widely cultivated in North and South America,Europe,Asia,Oceania and around the world.Following the rapid development of society,human more attention to the quality of life,So researches on vegetable quality traits are more and more. Pepper’s nutritional value is very high,rich in vitamin A,vitamin B,and vitamin C,vitamin C content accounted for the first in vegetables,Vitamin C content is an important criteria of judging of the quality of pepper fruits,Humans and most mammals can not synthesize vitamin by themselves, can only be obtained from food.Currently artificial synthetic vitamins and fresh fruits and vegetables are an important source of human vitamin supplements. Compared to artificial synthetic vitamins, humans pay more attention to the security of natural vitamin.Especially vegetables in our daily life is essential.So the research on the Vc content of Pepper Fruit has become particularly important.Firstly,high Vc content of pepper nurtured can meet people’requirements for the quality of pepper. It can also provide a good natural source of vitamins for human.Secondly,Inheritance of Vc content and gene mapping in pepper can play a guiding role for Pepper quality breeding.The experiment selected the pepper variety L5 including high vitamin C content as female,named P1.the pepper variety L158 including low vitamin content as male parent,named P2.and established six generations and text their Vc content,the correlation analysis in pepper Vc content of fruit and related traits.Using six generation joint analysis to research the inheritance of pepper Vc content.The use of two molecular markers SSR and AFLP methods to screen Vc content of pepper fruits associated molecular markers and QTL mapping.Experimental results show that:(1) Through the Analysis of the measured datas of Vc content of 253 plant in F2 population,showed that the Vc content in F2 population presents continuous variation trends,which was a typical of the normal distributions. The results showed that it was quantitative trait,by multiple control genes.(2)The correlation analysis of the Vc content of fruit and related traits showed Vc content was significantly positively correlated with average weight of single fruit, There was a significant negative correlation with the thickness of flesh, r=0.247, Vc content and fruit longitudinal diameter,fruit diameter,Soluble solids are not relevant.Studies have shown that in the same phenotype,increaseing the fruit weight,Vc content will increase, reducing the thickness of the flesh,Vc content will also increase.Therefore,in breeding high vitamin C content of pepper varieties,we should pay more attention to increase the pepper fruit weight,flesh thickness andreduces.(3)The experiment totally used 389 SSR markers and 256 AFLP markers to screen polymorphism, fiannally we obtained 61 pairs of polymorphism makers. Using the F2 as the mapping population, a genetic linkage map of pepper including 7 linkage groups,and 39 markers was constructed.the total length of the map was 1133.87 c M,The linkage group length ranging in41.7cM-331.31 cM.The average distance between markers was 29.02 cM.(4) The experiment applied six generations conjoint analysis to explore the inheritance of chili vitamin C content of fruit, combined with a multi-master gene combination gene mixed inheritance model analysis.The results showed that genetic model pepper fruits Vitamin C was C-0model, namely additive- dominance- epistatic gene mixed inheritance model.(5)Applying QTL Ici-Mapping 4.0 software,We combined F2 populations of pepper fruits Vc content data and molecular data of 253 plant.By inclusive composite interval mapping(ICIM)to inform QTL scanning,a total of 5 QTL loci associated with Pepper Vc content of fruit were detected.these QTLs could explain 9.64%-15.07% of total phenotypic variation.(6)The use of screened molecular markers CAMS811 and field measurement method respectively to determine vitamin C content of 50 pepper fruit germplasm resouces. Compared with the result of field measurement and the screening results coincide,The inosculation rate can reach to 80%,The marker CAMS811 was reliable.