Establishment of an efficient regeneration system using heading leaves of Chinese cabbage (Brassica rapa L.) and its application in genetic transformation
- Horticulture, Environment, and Biotechnology
- To preserve and propagate valuable Chinese cabbage (Brassica rapa L.) using mature vegetative organs without seeds, we established a high efciency regeneration system from heading leaf explants and further explored its application in genetic transformation. Our results showed that maximum shoot regeneration of cultivars ‘Beijing New No. 3’ (88.46±1.65%) and ‘Chengyangqing’ (73.77±1.73%) were obtained in the presence of 17.76 μM 6-benzylaminopurine (BA) and 5.37 μM α-naphthylacetic acid (NAA). The addition of silver nitrate (AgNO3) at 11.77 μM was essential for shoot regeneration from heading leaf explants. Genotypic diferences in shoot regeneration frequencies (from 47.24±3.65 to 88.46±1.65%) were observed amongst eight Chinese cabbage cultivars, in addition to the number of shoots per explant (from 1.31±0.02 to 2.02±0.05) in Murashige and Skoog medium containing 17.76 μM BA, 5.37 μM NAA and 11.77 μM AgNO3. Low temperature (4 °C) had an efect on in vitro preservation of leafy heads with a delay in leaf wilting, and there were no signifcant diferences in shoot induction frequency within 24 h for cultivars ‘Beijing New No. 3’ and ‘Chengyangqing’. In the genetic transformation experiments using selection with kanamycin (17.17 μM), a transformation efciency of 0.6–1.2% was achieved, as assessed from PCR and Southern blot results. The above results suggested that the heading leaf explants can not only achieve efcient seed-independent propagation of Chinese cabbage, but also provide a feasible platform for genetic transformation.