Jiangsu Agricultural College

Study on male sterility. VIII. Identification of a group of YII-1 type male-sterile cytoplasm

--Taichen Qin, Jianguo Chen, Mingliang, Xu, Dexiang Deng and Yunlong Bian

The relationship between maintainer and restorer, the number of restored genes, the resistance against Helminthosporium maydis race T and the banding pattern of mitochondrial DNA of T, C and S group male-sterile lines, as well as the YII-1 type male-sterile line we created by means of combining the cytoplasm of restored line with maintainer nuclei, were studied. The results show that there are many more restorer lines for the YII-1 type male-sterile line than for the T and C groups, but fewer than for the S group. The character of the restorer gene of the YII-1 type is different from that of the C group. Inoculating with Helminthosporium maydis race T and its pathotoxin (T-toxin), YII-1 type shows a much higher resistance than that of T, C and S groups (Fig. 1, Fig. 2). The modified method of Kemble, RJ and Pring, DR was used for identification of male-sterile line YII-1. Figure 3 shows high molecular weight bands were present in all lines. The S group possesses two unique mtDNAs, S1 and S2, that may be distinguished from other male-sterile cytoplasms. There are no obvious differences in mitochondrial DNA (mtDNA) banding pattern after agarose gel electrophoresis between T, C and YII-1 type male-sterile lines, but no S1 and S2 band within YII-1 type. YII-1 type may be a new type of male-sterile cytoplasm and different from the known groups.

Figure 1. The root length of Y-cytoplasm hybrid YII-1 B37 x Jin03. Left, T-toxin treatment: T-toxin did not inhibit the root growth of Y-cytoplasm corn, and the root length is equal between T-toxin treatment and check. Right: without treatment with T-toxin (check).

Figure 2. The root growth of T-cytoplasm hybrid cms-T B37 x Jin03. Left: without treatment with T-toxin (check). Right, T-toxin treatment: T-toxin highly inhibited the root growth of T-cytoplasm corn, and the root length in T-toxin treatment is about one third as long as that in check.

Figure 3. The tracks are respectively: Marker DNAs from bacteriophage digested with HindIII; Normal (N); T group; C group; S group; Y type.

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