Association analysis of yield and quality traits with SSR markers in cauliflower under spring cultivation

【Objective】The molecular markers related with curd yield and quality traits was explored by association analysis，which could provide candidate markers for utilization in marker-assisted breeding（MAS）of cauliflower in spring with high yield and high quality characters.【Method】Twenty-six pairs of simple sequence repeat（SSR）markers were used to unlock the population structure of 80 cauliflower inbred lines. The association analysis using the general linear model（GLM）in TASSEL 2.1 software was adopted to identify the SSR markers associated with three yield traits（curd weight, lengthways diameter and transverse diameter of curd）and four quality traits（contents of vitamin C, soluble sugar, chlorophyll and carotenoid）in curd of this population in spring 2018 and spring 2019.【Result】The results showed that two-year average of coefficient of variation（CV）of curd weight，lengthways diameter of curd，transverse diameter of curd，vitamin C，soluble sugar，chlorophyll and carotenoid of the inbred lines were 60.0%，20.7%，23.9%，27.3%，27.6%， 64.1% and 61.6%，respectively. It showed that the 80 inbred lines had rich genetic variation in curd yield and quality related traits. On basis of SSR marker data，the 80 cauliflower inbred lines were both classified into three categories by Neighborjoining analysis and population structure analysis respectively. The classification patterns of most cauliflower inbred lines were not consistent with their curd solidity or geographic origins. Further based on GLM analysis，a total of 6 SSR markers were found to be significantly associated with yield and quality traits in two years（P<0.05），whose explained variance ranged from 4.32% to 13.96%. Among them，the markers of Ol10F07 and BoGMS1042 were associated with curd weight， and the explanation rates were 7.71% and 13.96% respectively. Marker Na14H11 was associated with lengthways diameter of curd，and the explanation rate was 5.56%. Markers Na10D07，Na14H11，BoGMS1042 and BoDCTD1 were associated with transverse diameter of curd，of which BoDCTD1 had the highest explanation variation 12.89%. Markers Ra2F11， Na10D07 and Na14H11 were associated with vitamin C content，and Ra2F11 explained the highest variation（11.12%）. Marker Ra2F11 was associated with soluble sugar，chlorophyll and carotenoid contents，and the explanation rates were 11.25%，11.73% and 8.28% respectively.【Conclusion】Under spring cultivation, the 80 cauliflower inbred lines have rich genetic variation in yield and quality related traits，and 6 SSR markers were detected to be significantly correlated with the curd yield and quality traits of cauliflower. Moreover there is a phenomenon that the same marker was associated with multiple traits or the same trait is associated with multiple markers，which provides reference molecular markers for high-yield and high-quality breeding of cauliflower in spring.