Detection of quantitative trait loci controlling morphological traits in Brassica rapa L

Abstract

The Brassica species displays great variation with regard to morphology. However, the genetic mechanisms that underlie this variability are mostly unknown. We generated 188 F2 plants derived from a cross between a Chinese cabbage and a vegetable turnip, and scored several morphological traits (head formation, leaf lobe, pubescence, and turnip formation) twice (2005 and 2007) in two subsets of 94 individuals. With the exception of pubescence, we did not find any typical discrete segregation of these traits in F2 plants, suggesting that they are controlled by multiple genes. We constructed a linkage map to conduct quantitative trait locus (QTL) analysis, and detected eight and 14 QTLs in 2007 and 2005, respectively, for head formation, leaf lobe, pubescence, turnip size, and turnip weight. The amplified fragment length polymorphism (AFLP) fragments linked to the QTLs were converted into sequence-tagged site (STS) markers. The QTLs detected here and their linkage markers may provide useful information for the selection of traits during the breeding of Chinese cabbage and turnip cultivars.