玉米染色体G-带带型的研究

Studies of Chromosome G-banding Patterns in Maize

本文对3个玉米自交系,及其中两个自交系的杂交F_1有丝分裂早中期染色体的G-带带型进行了比较研究。所有的供试材料G-显带的染色体上都具有两种类型的带纹,我们称A型带和B型带。A型带为沿染色体长轴分布,较细的,密切邻近的多重带纹。不同自交系的A型带带型基本相同,杂交F_1的A型带无明显的异型性。非同源染色体间带型各不相同,某些染色体具有易于识别,特征性较强的A型带标记。B型带一般为深染色的大带,位于染色体的近端区。同一自交系每两个同源染色体的B型带可以配对,不同自交系B型带带型互有不同。杂交F_1某些染色体上的B型带带型异型性明显。具异型性的染色体对中一成员的带型与一个亲本相似,另一成员与另一亲本相似。比较对同一细胞先后作G-和C-显带处理的结果表明,B型带和C-带是相同的。

We studied G-banding patterns of mitotic early metaphase chromosomes of inbred lines Da Bt, 4 Zhangt and Gai Jin 55 as well as the F1 hybrids which were produced by crossing 4 Zhanga with Gai Jin 55. Two types of bands were observed in the chromosomes of all the experimental materials. We call them A type and B type bands respectively. A type bands were smaller, multiple and closely adjacent bands. They distributed all along the chromosome length. Different inbred lines were the same in A type banding patterns. There appeared no hetero-morphisms of the banding patterns in the F1 hybrids. All of the experimental materials had characteristics of A type banding patterns which could be recognized easily in some chromosome pairs. B type bands were more darkly stained and much bigger than A type bands. Two members of each chromosome pair can match in B type banding patterns of all the inbred lines. Different inbred lines were not the same in B type banding patterns. The F1 hybrids had heteromo-rphisms in B type bands of some chromosome pairs. In each of these chromosome pairs one of two members was similar to those of the paternal inbred line, the other similar to those of the maternal in B type bands. We treated the same cell with G- and C-banding procedures sequentially. The results demonstrate that B type bands -are equal to C-bands exactly.