QTL Mapping of Seed Color, Leaf Hairiness, Seedling Anthocyanin, Days to Flowering and Leaf Color in F2 Population of Brassica Rapa L.

A Diversity Arrays Technology (DArT) map was constructed to identify quantitative trait loci (QTL) affecting seed color, hairy leaf, seedling anthocyanin, leaf chlorosis and days to flowering in B. rapa using a F₂ population from a cross between two parents with contrasting traits. Two genes with dominant epistatic interaction were responsible for seed color. One major dominant gene controls the hairy leaf trait. Seedling anthocyanin was controlled by a major single dominant gene. The parents did not exhibit leaf chlorosis, however 32% F₂ plants showed leaf chlorosis in the population. A distorted segregation was observed for days to flowering in the F₂ population. A linkage map was constructed with 376 DArT markers distributed over 12 linkage groups covering 579.7 cM. The DArT markers were assigned on different chromosomes of B. rapa using B. rapa genome sequences and DArT consensus map of B. napus. Two QTL (RSC1-2, RSC12-56) were identified for seed color located on A8 and A9, explained 19.4% and 18.2% of the phenotypic variation, respectively. The seed color marker located in the ortholog to Arabidopsis thaliana Transparent Testa2 (AtTT2). Two QTLs RLH6-0 and RLH9-16 were identified for hairy leaf and explain 31.6% and 20.7% phenotypic variation, respectively.  A single QTL (RSAn-12-157) on A7, that explains 12.8% of phenotypic variation, was detected for seedling anthocyanin. The seedling anthocyanin DArT marker is found within the  Arabidopsis thaliana Transparent Testa12 (AtTT12) ortholog. A QTL (RLC6-04) for leaf chlorosis was identified and explain  55.3% of phenotypic variation. A single QTL (RDF-10-0) for days to flowering was identified that explains 21.4% phenotypic variation.