MOLECULAR STUDIES ON NUCLEAR GENE(S) INTERACTING WITH RYE CYTOPLASM Construction of YAC library with telomere sequences

在具有黑麦细胞质的普通小麦品系中，发现至少存在一个被称为“侏儒”的小型染色体。侏儒染色体在减数分裂时不与任何小麦染色体配对，并且没有该染色体的该品系的种子由于其胚乳败育而不能存活，甚至可以发芽，它们是高度不育的。这些结果表明，侏儒染色体来源于黑麦染色体的某些片段，具有黑麦细胞质功能所必需的基因。为了分析该基因，本研究尝试用代表性差异分析（RDA）和随机扩增多态性DNA（RAPD）方法扩增侏儒染色体特异性DNA序列。此外，我们构建了一个含有（cereale）-CS端粒序列的YAC文库，以拟南芥（Arabidopsis thaliana）的端粒序列为探针进行菌落杂交，结果表明400个酵母转化子中有80个克隆携带植物端粒。虽然在该文库中发现了高达600 kb的YAC克隆，但插入片段大小通常小于预期; <20 kb。迄今为止，有人提出以黑麦基因组DNA为探针，通过菌落杂交从侏儒染色体上获得100 kb-YAC。

In a common wheat strain with rye cytoplasm, at least one diminutive chromosome, called "midget" is found to occur. The midget chromosome does not pair with any of the wheat chromosomes at meiosis, and the seeds of this strain without this chromosome are inviable because of their endosperm abortion, and even germinable, they are highly sterile. These results indicate that the midget chromosome was derived from certain segment(s) of rye chromosome(s), having the gene(s) essential for rye cytoplasmic function. To analyze the gene(s), in this study, we attempted to amplify the midget chromosome-specific DNA sequences by using the RDA (Representational Difference Analysis), and the RAPD (Random Amplified Polymorphic DNA) methods. However, no specific DNA was detected.Furthermore, we have constructed a YAC library that preferentially contains telomere sequences from (cereale)-CS.Colony hybridization with the telomere sequence of Arabidopsis thaliana as a prove exhibited that about 80 clones of 400 yeast transformants carried plant telomeres. Although u up to 600kb-YAC clones were found in this library, the insert size was generally samller than expected ; <20kb. So far, a 100kb-YAC has been suggested to be derived from the midget chromosome by colony hybridization with rye genomic DNA as a probe.