拟南芥（Arabidopsis thaliana）体细胞胚胎发生体系中的体细胞类减数分裂研究

在拟南芥生态型LandsbergErecta体细胞胚胎发生体系的胚性愈伤组织中观察到2种类型的体细胞减数分裂现象。一种是体细胞染色体减数分组，其中，处于前期或中期的细胞染色体分为2个或2个以上的组。其共同特点是，染色体直接分开，未观察到纺锤体，从染色体的形态也看不出纺锤体的作用。染色体减数分组较多发生于多倍体细胞中。另一种类型是体细胞减数分裂，这种类型类似于大小孢子发生过程的减数分裂，如第一次分裂前期也有染色体的联会和配对。在脱分化培养基上的胚性愈伤组织中，单倍体细胞约占3%，四倍体细胞约占4%。经体细胞类减数分裂产生的细胞都发生染色体重组。

Meiosis-like Reduction in the Culture System for Somatic Embryogenesis of Arabidopsis thaliana

The somatic meiosis-like reduction was observed in some cells in the embryogenic calli of Arabidopsis thaliana. One type was somatic chromosome reductional grouping, in which the chromosomes in a cell either separated into two groups, or separated into more than two groups at prophase or metaphase. The chromosomes separated directly, the morphology of the chromosomes did not show any role of the spindle fibers. Chromosome reductional grouping happened more frequently in polyploid cells. The other type was somatic meiosis which was analogous to that existed in the process of gametogenesis, and characterized by the pairing and synapsis of homologues chromosomes. In the embryogenic calli cultured on dedifferentiation medium, about 3% of the observed cells contained haploid number of chromosomes, while the tetrad cells occurred at a frequency of about 4%. The somatic meiosis-like reduction could result in the recombination of chromosomes in the cells generated by these processes. The roles of somatic meiosis-like reduction in the somatic embryogenesis and somaclonal variations were discussed.