| Genetic analysis of the compatible relationship between
nuclear genes and cytoplasmic factors in wheats and their wild relatives
I. OHTSUKA Laboratory of Biology, Faculty of Engineering Kanagawa University, Kanagawa-ku, Yokohama 221, Japan It has been demonstrated previously that there are three types of tetraploid wheat nucleus, with regard to compatibility with the cytoplasm of Aegilops squarrosa (Ohtsuka 1983). Majority of Emmer wheats (AABB genomes, 9 strains of Triticum dicoccoides, 17 of T. dicoccum, 12 of T. durum, 3 of T. turgidum, 2 of T. polonicum, 2 of T. aethiopicum, 1 of T. persicum=carthlicum, 1 of T. isphahanicum and 1 of T. orientale=turanicum) were classified as AB type with no compatibility to squarrosa cytoplasm. All of Timopheevi wheats (AAGG genomes, 24 strains of T. araraticum and 9 of T. timopheevi), except one strain, were classified as AG type with complete compatibility to squarrosa cytoplasm. And, some species or strains of Emmer wheats (3 strains of T. dicoccoides, 9 of T. persicum, 4 of T. palaeocolchicum=georgicum, 4 of T. pyramidale and 2 of T, orientale) and one exceptional strain of Timopheevi wheat (1 of T. araraticum) were classified as AB' type with incomplete compatibility to squarrosa cytoplasm. In Table 1, these three types of response of tetraploid wheat nuclus were summarized. The AB type nuclei were considered incompatible with squarrosa cytoplasm, because strict zygotic lethality of the cytoplasm-genomic constitution of (squarrosa)AABB and selective sterility of male gametes of (squarrosa)AB were manifested. And, the 1D chromosome of Ae. squarrosa was indispensable for the compatible relation between the AB type AB genomes and squarrosa cytoplasm. On the other hand, AG type nuclei were considered complete compatible with squarrosa cytoplasm, because the normal plants with the genetic constitution of (squarrosa)AAGG were obtained. When the (squarrosa)AABB+1D lines of AB type Emmer wheats were crossed with the AG type Timopheevi wheats (as male), all of the F1 seed, including (squarrosa)AABG+1D and (squarrosa)AABG, were viable and normal, and all of the F1 seedlings, including 2n = 29 and 2n = 28, developed to the plants with normal growth (normal plant). Different from the AB type and AG type nuclei, the AB' type nuclei were considered incomplete compatible with squarrosa cytoplasm. When the (squarrosa)AABB+1D lines of AB type Emmer wheats were crossed with the AB' type Emmer wheats (as male), all of the F1 seed were viable, no abortive seed (zygotic lethal) appeared, but only the seed with 1D chromosome were normal and the seed without 1D chromosome were shriveled because of incomplete development of endosperm. And, in the F1 seedlings, obvious segregation was also appeared. The F1 seedlings with 1D chromosome (2n = 29) grew to normal plants, but the F1 seedlings without 1D chromosome (2n = 28) turned to be midget plants with extreme reduction of plant vigour and with severe chlorophyll variegation under low temperature. Gene analysis was conducted with regard to the difference in squarrosa cytoplasm compatibility between AB type and AB' type Emmer wheat species. |
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