柑橘抗寒细胞变异体的获得及其抗性遗传稳定性的研究

Selection of Cold Tolerant Somaclonal Variant from Citrus sinensis cv. Jincheng and Genetic Stability Evaluation of Its Cold Tolerance

锦橙（Citrussinensis（L．）Osbeckcv．Jincneng）珠心愈伤组织悬浮细胞通过γ射线诱变与高浓度羟脯氨酸离体选择的方法，获得了抗性细胞系，并再生植株。抗性细胞系及其再生植株比供体（对照）的抗寒性分别提高1．4℃和24℃，连续3年测定结果表明再生植株抗寒性的增强是稳定的。其叶片总DNA的RAPD分析说明供体与变异植株可能在DNA水平上存在细微的差异，冷驯化进一步加强抗性细胞系与再生植株在抗氧化酶SOD、过氧化氢酶（CAT）活性和脯氨酸（Pro）、丙二醛含量上的差异。变异系抗性增强的生理基础涉及Pro代谢外的其他途径，抗氧化酶活性的提高与其抗寒性的增强有关。

Somaclonal tolerant cell line and its regenerants were obtained from suspension culture cells of nucellar calli in Citrus sinensis (L.) Osbeck cv. Jincheng via gammma ray mutagenesis and in vitro selection withconcentrated bydroxyproline, which were cold tolerant at 1.4 ℃ and 2 .4℃ more than the suspension cells ofwild types respectively. The capability of enhanced cold tolerance in the valiant plantlet L3-1 was geneticallystable based on a three-year evaluation. There might be slight differences between their total DNA from leavesof L3-1 and the wild type according to the polymorphism between their total DNA RAPD patterns. Except proline accumulation either at the suspension cell or at the plantlet levels, antioxygenases SOD and CAT activitieswere stimulated much higher and MDA contents much lower than the wild type after cold acclimation at thesuspension cell levels, which indicated that physiological mechanism on the enhanced cold tolerance of thevariant was very complex. Not only proline metabolism, but antioxygenases and some others were also involvedin its enhancement process on cold hardiness.