柑橘愈伤组织倍性变化及其与体细胞胚胎发生能力的关系

柑橘愈伤组织是细胞融合、遗传转化等生物技术研究的良好材料。本实验室通过近20年的工作，先后诱导和保存了近80份不同种类和品种的柑橘愈伤组织。这些愈伤组织在MT基本培养基上继代保存。在长期保存过程中，部分材料仍然保持较好的胚胎发生能力。为研究愈伤组织在继代过程中的染色体变异趋势以及这种变异对胚胎发生能力的影响，本文选择有代表性的35份材料作为试材，在4年中连续3次使用流式细胞仪，对细胞DNA含量进行测定。结果发现，待测的35种愈伤组织均存在部分细胞DNA含量加倍的现象，而且，随着时间的推移，除佩奇橘柚、沙漠蒂甜橙、鲁斯脐橙、印度酸橘等4种愈伤组织的DNA含量加倍的细胞有减少的趋势外，其他愈伤组织的DNA含量加倍的细胞均有增加的趋势。数据分析表明，在待测的35种愈伤组织中，有71．4％的基因型的愈伤组织细胞出现了多倍体细胞增加的趋势。对这35种柑橘愈伤组织进行体细胞胚诱导，发现只有9种愈伤组织具有不同程度的胚胎发生能力，其他26种愈伤组织不能再生。相关性分析表明，柑橘愈伤组织细胞DNA含量增加的细胞比例与体细胞胚胎发生能力之间的相关性较小，相关系数为忙-0．10（P〈0．01），未达到显著水平。另外，柑橘胚性愈伤组织继代时间与体细胞胚胎发生能力之间的相关性也不显著。

Relationship Between Ploidy Variation of Citrus Calli and Competence for Somatic Embryogenesis

This study focuses on the relationship between the genetic variation of calli and the competence for somatic embryo-genesis in citrus. The DNA content of 35 citrus calli of different genotypes was measured three times by flow cytometry during a period of four years. The results showed that 71.4 % of the genotypes had a progressive increase of varied cells, while those of Page tangelo, Shamouti sweet orange, Russ navel orange and Cleopatra decreased; significant difference in the variation degree (per-centages) existed among genotypes. Studies carried out on the induction of somatic embryogenesis revealed that 9 out of the 35 genotypes had still kept the competence of somatic embryogenesis, and the rest 26 had lost the competence. Correlation analysis indicated that there was no significant relationship between the variation degree and the embryogenesis competence r=-0.10 (P<0.01), neither for the relationship between the subculture duration and the regeneration capacity.