摘要
Rapeseed (Brassica napus) is the second largest oil crop in the world. However, transformation efficiency of rapeseed still needs to be improved. To evaluate non-procedural factors (e.g. explants, section of explant, marker genes and number of exogenous genes) effects on transformation efficiency, 6-day-old hypocotyl explants from in vitro grown seedlings were co-cultivated with Agrobacterium strain GV3101 harboring a binary vector using optimized transformation procedure. Results showed that normal maturing variety ‘Zhongshuang 6 (ZS6)’ had the highest overall capacity to produce rooted shoots among 5 common varieties and 6 early maturing varieties, with green callus induction rate 81.45% and shoot regeneration rate 21.66%. Early maturing variety 14M645 has relatively high regeneration rate (4.69%) and one of the shortest growth periods (107.54 d). Data showed that choosing neomycin phosphotransferase II gene (NPTII) as selectable marker led to the best transformation rate (17.38%). Selecting upper hypocotyl segments near cotyledon as explant provided the higest transformation efficiency, with regeneration rate of 25.59% when using NPTII as selectable marker and 22.19% for Bar. B. napus transformed with single gene showed higher transformation frequency than vectors with multiple genes,highlighting difficulty of multiple gene transformation. This work helped to further improve genetic transformation of B. napus by optimizing factors that impact transformation efficiency,and it would ultimately improve research in transgenic B. napus varieties with commercial potential.
