Studies on the differentiation of genepools in rice

植物育种主要是通过杂交从自然产生的变异体中选择有利的基因组合。由于物种具有原始的基因库作为适应的遗传材料，差异基因库与杂交育种的困难密切相关。本研究的目的是揭示水稻类群间的基因库差异，并探讨其原因。基因多样性进行了检查关于Wx和C基因控制直链淀粉含量和花青素着色，因为这些变化是不同的品种比野生近，无论在水稻驯化过程中的遗传瓶颈效应。Wx基因的序列分析表明，驯化后至少建立了5个等位基因。这些等位基因是由RNA加工和氨基酸的移码和变化引起的。在水稻品种中显示等位基因多样性的C基因与编码Myb样蛋白的玉米cl基因同源，序列分析表明，水稻品种C基因的非同义突变频率高于野生祖先，表明C基因的这种变异可能是在驯化过程中被正向选择的。内部障碍也进行了检查，因为它们作为分化genepool的机制。通过精细定位和基因表达检测，发现了一个位于wx附近的杂种不育基因S10。此外，在第6染色体上至少有3个基因对水稻的杂交不亲和性起着重要作用。这一结果将有助于它们的分子克隆，以了解它们在水稻基因组分化过程中的分子进化。

Plant breeding is mainly to select favorable gene combinations from naturally occurring variants through hybridization. Since species have the primary genepool which is used as the genetic materials for their adaptation, the differential genepool is closely related with the difficulties in hybridization breeding. The objectives of the present study is to reveal the differentiated genepool among rice taxa and to examine the causal factors. The genic diversity was examined regarding to Wx and C genes controlling amylose content and anthocyanin coloration since these variations are distinct among cultivars than in wild relative regardless of the genetic bottleneck effects during the rice domestication. Sequence data of the Wx gene revealed that at least 5 alleles have been established after the domestication. The alleles resulted from frameshifts and changes in RNA processing and amino acids. The C gene showing allelic diversity in rice cultivars was found to be the homolog of maize cl encoding Myb-like protein.Sequence data showed that the frequency of non-synonymous mutations was high in the C of rice cultivars than the wild progenitor, indicating that such alteration in C might have been positively selected for during the domestication process. The internal barriers were also examined since they act as the mechanism of differentiated genepools. A hybrid sterility gene, S10, was located near wx and the candidate was detected by fine mapping and gene expression. In addition, at least 3 genes on chromosome 6 were found to play a significant role for cross-incompatibity in rice. The results will contribute for their molecular clonning to figure out their molecular evolution during the differentiation of genepools in rice.