Specific interaction between the D genome and the three alien cytoplasms in wheat.

Abstract

In order to clarify the specific nucleo-cytoplasmic interactions between the D genome chromosomes in common wheat and the Ae. squarrosa, Ae. cylindrica and Ae. crassa cytoplasms, we produced three aneuploid series of the D genome chromosomes, i. e., ditelosomics, monosomics and nullitetrasomics, of Triticum aestivum L. cv. Chinese Spring with the above three cytoplasms. And, the seed fertilities of these lines were investigated.Seven ditelosomic lines with the squarrosa cytoplasm had high fertilities. However, ditelo-2Dα and -7DS with the crassa cytoplasm showed highly reduced fertilities. Their fertility reduction was mainly due to pistillody.We produced 18 monosomics of the D genome chromosomes with the three alien cytoplasms, except mono-5D with the squarrosa cytoplasm and mono-2D and -5D with the crassa cytoplasm. Every monosomic line had high seed fertility, although several lines showed slight reduction when compared with the corresponding normal monosomic lines.By backcrossing the three cytoplasm substitution lines with nullitetrasomics, we attempted to obtain the nullitetrasomics with the alien cytoplasm. As a result, twelve lines, which were all fertile, were obtained. However, chromosomal segregations were biased particularly in the crosses between mono-1D tri-1A plants with the three alien cytoplasms (_??_) and the normal nulli-1D tetra-1A's (_??_), and none of nulli-1D tri-1A's and nulli-1D tetra-1A's was obtained. Furthermore, mono-1D tri-1A's with these cytoplasms showed extreme reduction of seed fertility when pollinated by nulli-1D, while normal seed fertility by the disomic. Ditelo-1DL plants with those alien cytoplasms were normally fertile. Taking all these results in consideration, we concluded that the viability gene(s) against the three alien cytoplasms is located on the long arm of the 1D chromosome of common wheat.