大白菜下胚轴离体不定芽高效再生体系的研究

Studies on High Efficient System for in vitro Shoot Regeneration from Hypocotyls of Chinese Cabbage

以大白菜的下胚轴为外植体,比较了不同浓度TDZ和6-BA两种细胞分裂素与不同浓度NAA相配合的培养基上不定芽再生的差异,并利用筛选出的高效再生培养基研究外植体苗龄、切段来源、接种方式以及品种对不定芽再生的影响.结果表明:与6-BA相比,TDZ对诱导下胚轴不定芽再生更有效,在MS+TDZ 0.3 mg·L-1+NAA 0.5 mg·L-1+AgNO3 5 mg·L-1的培养基上,下胚轴不定芽再生频率高达87.8%,平均每下胚轴再生不定芽数也达到15.1个;3～5 d苗龄之间的下胚轴不定芽再生能力无显著差异,再生频率均达到80%以上,此后随着苗龄的增加,不定芽分化频率快速下降,苗龄为7 d时再生频率只有51.1%;下胚轴不同切段不定芽再生能力由强到弱表现为:上部切段>中部切段>下部切段;以正插(形态学下端插入培养基)方式接种的外植体不定芽再生能力显著大于反插(形态学上端插入培养基)和平放的;不同品种大白菜下胚轴的不定芽再生能力有一定差异.

The hypoeotyls of Chinese cabbage [Brassica campestris ssp. pekinensis （L.） Olsson] were used as explants in this experiment. Differences of NAA combined with TDZ or 6-BA in adventitious shoot regeneration from hypocotyl explants were compared and the best hormone combination was selected to study the effects of seedling age,hypocotyl sources,inoculation methods and cultivar difference on shoot regeneration. The results were as follows. Compared to 6-BA, TDZ was more effective in adventitious shoot regeneration. The shoot regeneration percentage reached 87.8% and there were 15.1 shoots regenerated per explant in the MS medium containing 0. 5 mg·L^-1 NAA,0. 3 mg·L^-1 TDZ and AgNO3 5 mg·L^-1. There was no significant difference among hypocotyls of 3 to 5 days of seedling age in their regeneration frequencies which were above 80% respectively,increasing of seedling age resulted in a reduction of shoot differentiation frequency,which was only 51.1% at the seedling age of 7 days. The order of shoot regeneration ability of hypocotyl segments from different positions was.the upper,the middle,the lower. Hypocotyls inoculated with their abaxial ends up were more effective in shoot regeneration than those were either inoculated with their abaxial ends down or placed horizontally. Different cultivars showed difference in shoot regeneration ability.