Abstract
Brassica villosa is characterized by its dense hairiness and high resistance against the fungal pathogen Sclerotinia sclerotiorum . Information on the genetic and molecular mechanisms governing trichome development in B. villosa is rare. Here, we analyzed an F 2 population, derived from a cross between B. villosa and the glabrous B. oleracea by QTL mapping and transcriptomic analyses. As a result, the phenotyping of 171 F 2 progenies revealed a wide range of variation in trichome development. Subsequent genotyping with the 15-k Illumina SNP array resulted in a genetic map with 970 markers and a total length of 812 cM. Four QTLs were identified, which explained phenotypic variation from 3.2% to 40.3%. Interestingly, one of these was partially co-localized with the major QTL for Sclerotinia-resistance previously detected in the same F 2 population. However, only a moderate correlation between trichomes and Sclerotinia-resistance was observed. In total, 133 differentially expressed genes (DEGs) associated with trichome development were identified, from which only BoTRY , an orthologue of Arabidopsis TRY encoding a MYB transcription factor negatively regulating trichome development, was located within the major QTL. Expression of BoTRY was tissue-specific and highly variable between the hairy and glabrous species, suggesting that BoTRY may also act as a master-switch regulator of trichome development in B. villosa . This study provides valuable data for further understanding the genetic architecture of trichome development and identifying related genes and mechanisms in Brassica species . Molecular markers can be developed to facilitate the introgression and selection of this trait in oilseed rape breeding.