摘要
ＲＦＬＰ标记ｂｎ１８．２３和 ｕｍｃ１１１位于玉米遗传日第 ４连锁群近端，彼此密切连锁但次序尚未确定。用生物素标记对它们进行了原位单杂交和共杂交的比较定位。在植物中，这类原位共杂交的研究为首次报道。在单一探针的原位杂交中 ｕｍｃ１１１被定位在第 １、 ４和９染色体长上，与着丝粒的百分距离分别是７．３６±２．６５、６３．６７±１．０７、４７．８７±２．９０。ｂｎ１８．２３被定位在第４和８染色体长臂上，与着丝粒的百分距离分别是８７．４２±２．４５和２７．６０±１．７５，清楚地表明了这两个标记在第４染色体上的次序。ｂｎ１８．２３和ｕｍｃ１１１分别与编码过氧化氢酶的ｃａｔ３基因和编码丝氨酸／苏氨酸蛋白激酶的ｃｄｅ２Ａ基因紧密连锁。根据供试ＲＦＬＰ标记检出位点推断了基因ｃｄｃ２Ａ和ｃａｔ３的物理位置。原位共杂交在第 ４染色体长臂上同时显示出了ｕｍｃ１１１和ｂｎ１８．２３两个标记的杂交信号，它们的位置分别与单一探针原位杂交的位置基本吻合。这为低拷贝或单一拷贝等小片段ＤＮＡ物理定位的可靠性以及它们共杂交的可行性提供了令人信服的证据。
The RFLP markers bn18.23 and umc111 were previously located in the subterminal region of the fourth linkage group of maize. They are linked closely, and the order has not been determined. In this study, they are physically mapped by biotin-labelled in situ hybridization and cohybridization. It is the first report for in situ cohybridization in plants. The marker umc111 is located on the long arm of chromosomes 1,4 and 9. The distance Percentages from the hybridization sites to the centromeres are 7.36±2.65, 63.67±1.07 and 47.87±2.90 respectively. The marker bn18.23 is mapped on the long arm of chromosomes 4 and 8. The distance Percentages are 87.42±2.45 and 27.60±1.75. The order among these two markers and the cetromere has been confirmed. The markers bnl8.23 and umc111 link closely with gene cat3 encoding catalase and gene cdc2A encoding serine/threonine protein kanases respectively. According to the physical positions of the tested markers those of genes cat3 and cdc2A are deduced basically. The signals of both umc111 and bn18.23 are showed on the long arm of chromosome 4 simultaneously by cohybridization. It demonstrates that the in situ hybridization location of low or single copy DNA is reliable completely.
基金
国家自然科学基金!编号39370394
国家教委博士点基金!编号109931112
