Identification of quantitative trait loci for yellow inner leaves in Chinese cabbage (Brassica rapa L. ssp. pekinensis) based on SSR and SRAP markers

Yellow inner leaves are a valuable agronomic trait in Brassica rapa L. ssp. pekinensis (B. rapa) due to its higher nutritional content and huge economic value. The objective of the present study is to determine the heritability of yellow inner leaves, to construct a genetic linkage map, and to map the quantitative trait loci (QTLs) controlling this trait. An F2:3 population was generated from a cross derived from 07A237 and Chiifu, which are excellent inbred lines having yellow and white inner leaves, respectively. A linkage map was developed with 71 SSR and 145 SRAP markers, covering a total genetic distance of 819.4 cm and an average map distance of 3.8 cm. With the anchor SSR markers, the present map could be aligned to previously reported genetic maps, and the corresponding chromosome of the B. rapa A genome. Three QTLs controlling yellow inner leaves, accounting for 40% of the phenotype variance, were identified with composite interval mapping analysis. The present study could be a reference for QTL studies of yellow inner leaves in B. rapa. Our findings can be used to identify markers linking to the QTLs for marker-assisted selection in the practical breeding program.

► A precise colorimeter CR-400 was used to estimate the phenotype value of inner leaf. ► A genetic map was constructed by using 71 SSR and 145 SRAP molecular markers. ► SSR markers enable us to compare the present genetic map to some reported maps. ► Three QTL loci were identified with composite interval mapping analysis. ► Different phenotype value measuring method has impact on QTL identification.