Establishment of Agrobacterium-mediated genetic transformation and application of CRISPR/Cas9 genome-editing system to Brassica rapa var. rapa

Genome editing is essential for crop molecular breeding. However, gene editing in turnip (Brassica rapa var. rapa) have not been reported owing to the very low transformation efficiency.In this study, we established a transformation procedure involving chemical-inducible activation of the BrrWUSa gene, which resulted in high transformation frequencies of turnip. Estradiol-inducible BrrWUSa transgenic plants were fertile and showed no obvious developmental defects. Furthermore, we used CRISPR/Cas9 gene-editing technology to edit BrrTCP4b and generated 20 BrrTCP4b-edited seedlings with an increase in leaf trichome number.The results demonstrate that BrrWUSa improves the regeneration efficiency in turnip. The transformation procedure represents a promising strategy to improve genetic transformation and for functional characterization of genes in turnip.