Abstract: The objective of this study was to map and analyze QTLs controlling leaf-lobed trait in the population constructed by Chinese cabbage ‘Z16’ [Brassica campestris L. ssp. pekinensis（Lour）Olsson] and ‘Yellow Sarson 143’ （Brassica campestris L. var. yellow sarson Prain），so as to provide information
for molecular marker assisted selection in Chinese cabbage breeding. Leaf-lobed trait was detected in parents and individuals of BC2DH population of Z16 × 143 in different growing seasons. An integrated map of 559.08 cM with 10 linkage groups was also used for the QTL analysis. Using the genetic map and
multiple QTL model（MQM）method of software package MapQTL（version 4.0），QTLs were detected in the same position on 3rd and 10th chromosomes in the three different growing seasons. The LOD values varied from 7.66 to 18.99 which explained 26.4% - 44.7% of the phenotypic variation. When analyzed with annotated genes between Arabidopsis thaliana and B. rapa in the QTL region on 10th chromosome，one active GA biosynthetic gene was found as the candidate gene for the leaf-lobed trait. The lobed phenotype was inhibited with application of exogenous GA₃ in line 143.

Key words: Chinese cabbage, Brassica campestris, leaf-lobed trait, quantitative trait locus（QTL）, BrGA20ox3