Establishment of A Simple and Efficient Agrobacterium-mediated Genetic Transformation System to Chinese Cabbage(Brassica rapa L. ssp. pekinensis)

Chinese cabbage, belonging to Brassica rapa species, is an important vegetable in Eastern Asia. It is well known that Chinese cabbage is quite recalcitrant to genetic transformation and the transgenic frequency is generally low. The lack of an efficient and stable genetic transformation system for Chinese cabbage has largely limited related gene functional studies. In this study, we firstly developed a regeneration system for Chinese cabbage by optimizing numerous factors, with 93.50% regeneration rate on average. Based on this, a simple and efficient Agrobacteriummediated genetic transformation method was established, without pre-culture procedure and concentration adjustment of hormone and AgNO3 in co-cultivation and selection media. Using this system, transformants could be obtained within 3.5–4.0 months. Average transformation frequency is up to 10.83%. The establishment of this simple and efficient genetic transformation method paved the way for further gene editing and functional studies in Chinese cabbage.