Construction of an Intragenic SSR-Based Linkage Map and QTL Mapping for Agronomic Traits in Chinese Cabbage (Brassica rapa L. ssp. pekinensis)

Abstract

Chinese cabbage (Brassica rapa L. ssp. pekinensis) is one of the most widely cultivated and economically important vegetables in China. Constructing an effective genetic linkage map and mapping quantitative trait loci (QTLs) related to yield and leafy head morphology is of great importance for molecular breeding of Chinese cabbage. Using two diverse Chinese cabbage inbred lines, ZHB and G291, as parents, an F2 segregating population consisting of 240 individuals was prepared for genetic map construction and phenotype investigation in this study. The two parents are significantly different in both shape and size. Sixteen important agronomic traits of F2 individuals were investigated. A genetic map of 105 intragenic simple sequence repeat (SSR) markers distributed across 10 linkage groups (LGs) was constructed, which was 2034.1 cM in length and had an average inter-locus distance of 21.75 cM. We identified 48 QTLs for the tested important agronomic traits on the studied LGs, with LOD scores of 2.51–12.49, which explained the phenotypic variance of 3.41–26.66%. The QTLs identified in this study will facilitate further genetic analysis and marker-assisted genetic improvement of Chinese cabbage.

Genetic and Transcriptome Analysis of Leaf Trichome Development in Chinese Cabbage (Brassica rapa L. subsp. pekinensis) and Molecular Marker Development

“…In our previous study [ 36 ], a genetic map was constructed based on the two inbred lines of Chinese cabbage, “ZHB” and “G291”, and their F 2 population. Based on this genetic map, genes related to trichomes were located on chromosome A06 with a phenotypic variance (PVE) of 47% ( Table 2 ).…”

“…Intragenic SSRs, especially the expressed sequence tags SSRs (EST-SSRs) in the transcriptional sequences, have been widely used in genetic linkage map construction in plants because these SSRs are more conserved and transferable than extragenic SSRs [ 40 , 41 , 42 , 43 ]. In our previous study [ 36 ], a genetic map was constructed using 105 co-dominant polymorphic SSRs in 240 individuals of the F 2 segregating population crossed between two Chinese cabbage inbred lines, ZHB and G291, from which a candidate gene, BrGL1 , was located on chromosome A06.…”

“…QTL mapping of candidate loci for controlling trichome development in Chinese cabbage was performed using the genetic map constructed in our previous study [ 36 ].…”

“…A total of 240 F 2 individuals were planted in Changqing, Jinan, China, with a row placing of 50 cm and a plant placing of 50 cm. The detailed description of the mapping population and methods were according to Gao et al (2022) [ 36 ].…”

Harvesting Knowledge: Illuminating Advances in Brassica Crops Genomics and Breeding

“…The SI features three papers, each focusing on essential aspects of genetic mapping and improvement in B. rapa. The first paper places a primary emphasis on constructing a comprehensive genetic map with 105 intragenic SSR markers distributed across 10 linkage groups [10]. This map serves as a valuable resource, providing insights into the intricate genetic architecture governing essential agronomic traits in Chinese cabbage.…”