染色体定位两个与玉米大斑病抗性基因Ht1连锁的RFLP标记

CHROMOSOME LOCATION OF TWO RFLP MARKERS umc22 AND umc122 TIGHTLY LINKED TO THE Ht1 GENE IN MAIZE 

以玉米（ＺｅａｍａｙｓＬ．）黄早四自交系为材料，采用生物素标记的染色体原位杂交技术，对与大斑病抗性基因Ｈｔ１紧密连锁的两侧两个ＲＦＬＰ标记ｕｍｃ２２和ｕｍｃ１２２进行了定位。结果表明，ｕｍｃ２２和ｕｍｃ１２２探针都同时与第２号和第７号染色体杂交，而且，ｕｍｃ２２也和第４号染色体杂交。这些结果反映了这两个ＲＦＬＰ标记的二重或三重分布。两探针平均信号检出率分别为２０４２％和１４４９％。ｕｍｃ２２和ｕｍｃ１２２在第２号染色体长臂上杂交信号与着丝粒的百分距离分别为５８３６±３．１９和６１０２±４３２；在第７号染色体长臂上杂交信号与着丝粒的百分距离分别为４４７０±２．１１和４５１９±２２７。这些结果表明，ｕｍｃ２２和ｕｍｃ１２２在第２号染色体上的物理图的相对位置与遗传图的相对位置相符，彼此间都相距很近，两个标记在第２号和第７号染色体的重复是连在一起发生的。由此推断，Ｈｔ１除位于第２号染色体ｕｍｃ２２和ｕｍｃ１２２之间的位置外。

A biotin labeled in situ hybridization technique was used in order to physically map two RFLP markers—umc22 and umc122—tightly linked to the Ht1 gene on the chromosomes of maize (Zea mays L.). The results showed that both markers located on the chromosomes 2,7 and umc22 also hybridized with chromosome 4, which demonstrated that the two markers were a duplicated or triplicated sequence. The average detection rate of in situ hybridization was 17.46%. The percent distances of umc22 and umc122 from centromere on the chromosome 2 were 58.36±3.19 and 61.02 ±4.32 respectively, and on the chromosome 7 were 44.70±2.11 and 45.19±2.27 respectively, which indicates that there are no differences between genetic and physical distances of two markers umc22 and umc122. It was deduced that the gene Ht1 should also have its homeologous sequence between the hybridization sites of umc22 and umc122 on 7 L besides its location between the two hybridization sites.