Analysis of polysomaty in plants and its evaluation for genetics and plant breeding

利用流式细胞术对重要经济植物的多体性分布进行了分析，并根据分析数据探讨了多体性植物的共同特征。结果表明，多体现象广泛存在于具有多肉器官的植物中，但也存在于某些分类单元的非多肉植物中，如石竹科植物。此外，木本植物很少有多体现象。这些结果表明，多体是在进化过程的不同方面独立获得的。除茎和根尖分生组织外，其余器官均存在多体现象，且倍性较高的细胞随年龄增长而增加。在人工诱导的四倍体中，多体模式向更高一级转移，但最高倍性细胞的比例呈下降趋势。在植物微繁过程中，多倍体作为一种体细胞无性系变异与多倍体的自发产生之间的关系也进行了研究。结果表明，从多倍体组织中诱导的细胞悬浮培养具有与原始组织几乎相同的多倍体模式，表明高倍性细胞具有与基础二倍体细胞相同的细胞分裂能力。由于在培养基中添加植物生长调节剂的种类和浓度会改变细胞的多倍体模式，因此植物生长调节剂被认为是培养细胞多倍体化的主要因素。在本研究中，发现DNA含量是区分不同分类群的有用指标。此外，流式细胞术对DNA含量不同的种间杂交获得的植株的杂种性鉴定以及同种种间杂交产生的多倍体杂种的母本鉴定都是有效的。

Flowcytometric analysis was conducted on the distribution of polysomaty in economically important plants and common features of the plants with polysomaty were investigated based on the data of the analysis. As the results, polysomaty was widely found in the plants with succulent organs, but it was also found in some non-succulent plants belonging to some taxons such as Caryophyllales. Moreover, woody plants rarely have polysomaty. These results suggest that polysomaty have been acquired independently at different aspects of evolutionary processes. Polysomaty was found in all organs except for shoot and root apical meristems and the cells with higher ploidy levels tended to increase with aging. In the artificially induced tetraploids, polysomaty pattern shifted to the one-step higher level but the proportion of the highest ploidy cells tended to decrease. Relationship between polysomaty and the spontaneous production of polyploids as a somaclonal variation during the micropropagation of plants was also examined. As a result, cell suspension culture induced from the tissue with polysomaty had almost the same pattern of polysomaty as the original tissue, suggesting that the cells with higher ploidy levels had the same ability for cell division as the basal diploid cells. Since the polysomaty pattern changed by the kind and concentration of plant growth regulators added to the culture medium, plant growth regulators are considered to be a major factor for the polyploidization of the cultured cells. In the present stydy, it was revealed that DNA content is a useful index for discriminating the different taxons, . Moreover, flow cytometric analysis of DNA contents was effective for confirming the hybridity of the plants obtained by the cross between the species which have different DNA contents, and for identifying the maternal parent of the interspecific polyploid hybrid produced by the cross between the species with the same nature.