Comparative analysis of MYB28 homologs and development of a MYB28-specific marker in Brassica napus L.

Abstract

Glucosinolates are a major class of secondary metabolites in Brassicaceae species, whose degradation products are proving to be increasingly important for human health and in crop protection. MYB28 is important for regulating glucosinolate biosynthesis in Arabidopsis thaliana. Brassica napus L. is one of the closest relatives of A. thaliana, and in theory, contains several MYB28 homologs in its genome. Only a few transcriptional regulators of aliphatic glucosinolate biosynthesis genes in Brassica crops have been functionally characterized. Therefore, the aims of this study were to clarify the distribution of MYB28 homologs in the B. napus genome, and to determine the gene expression status and function of these homologs, which may have important implications for plant breeding. Based on the A. thaliana MYB28 sequence, six BnMYB28 homologs were identified and mapped to six linkage groups of a doubled haploid population. Gene expression analyses revealed that the homologs exhibited different expression patterns in different tissues. Additionally, the function of BnA9.MYB28 was confirmed by generating BnA9.MYB28-overexpressing transgenic plants and completing association mapping analyses. One insertion/deletion marker was detected in cultivars with high or low glucosinolate contents. Our results highlight the importance of MYB28 homologs for regulating complex glucosinolate traits in the polyploid crop B. napus. The gene and marker information generated in this study may be useful for marker-assisted breeding of oilseed rape.