Fine-mapping of theBjPurgene for purple leaf color inBrassica juncea

摘要

Purple leaves are rich in health-protecting anthocyanins and food colorants inBrassica juncea. But the causal gene, which is related to leaf color formation, have not been reported inB. juncea. Anthocyanins mainly accumulated throughout the adaxial and abaxial epidermal leaf cells of purple leaves. A genetic analysis indicated that an incompletely dominant gene controls the purple leaf trait inB. juncea. Furthermore, theBjPurgene, which increased anthocyanin accumulation in purple-leaf mustard, was cloned. Blast and phylogenetic analyses revealed that BjPur encodes a new R2R3-MYB transcription factor. Sequence analysis of two alleles revealed a DNA sequence insertion in the first intron ofBjPurin green leaves parent line (LY) when compared with theBjPurgene in the purple-leaf parent line (ZY). And this insertion greatly reduced the transcription ofBjPurin green leaves. In purple-leaf plants, the transcript level ofBjPurwas significantly higher in leaves than in roots, stems, siliques, and flower buds. Additionally, molecular markers linked to leaf color were developed to distinguish different genotypes ofB. juncea. These results will be helpful for the genetic improvement of the purple leaf color inB. juncea.