| III. Research Activities 1. Biochemical study (i) Nucleic acid - DNA contents per nucleus of a common wheat (Chinese Spring), a synthesized hexaploid wheat (ABD No. 1), and its parental species were microspectrophotometrically measured using resting nuclei in embryos. According to the result obtained, there exists the following relationship between their DNA contents; (Chinese Spring) = (ABD No. 1) = (T. dicoccoides + Ae. squarrosa var. typica). (ii) Protein - Endosperm protein and amylase in embryos have been studied by the cyanogum method of electrophoresis. Seven bands for the former and eight bands for the latter were separated and found to be different quantitatively or qualitatively among various species of wheat and its relatives. Common wheat appeared in this regard to be comparable to the combination of emmer wheat and Ae. squarrosa. Einkorn and Ae. squarrosa were markedly different from each other. 2. Cytogenetic study (i) Gene distribution - Distribution of genes controlling necrosis and chlorosis has been investigated in Japanese and U.S. wheat populations. No difference was found on the chlorosis genes, while distribution pattern of necrosis genes was quite different between the two populations; Ne1 gene predominates in Japan, while Ne2 is prevalent in U. S. A. In order to clarify the genic system controlling the second type of necrosis (Net-system), F1 hybrids between Chinese Spring (net1net2) monosomics and Prelude (Net1net2) were test-crossed to ABD No. 1 (net1Net2) and the resulting hybrids are under observation. Distribution of complementary genes, Dw1 and Dw2, for dwarfness is also under investigation by making crosses between Japanese and U. S. wheats to two testers, T. spelta (Dw1dw2) and ABD No. 1 (dw1Dw2). Four varieties of both Japan and U. S. A. were crossed to Chinese Spring monosomics in order to investigate genes for waxiness of foliage. (ii) Chromosome differentiation - Mono-5A, 5B and 5D of Chinese Spring were crossed to seven Japanese varieties. Chromosomes 5A, 5B and 5D of these Japanese varieties will be studied in those F1's in regard to their morphology and will be compared with those of American varieties. (iii) Genomic differentiation - As a means of investigating genomic differentiation between Japanese and American wheats, nullisomic series of Japanese wheat will be compared to that of American variety. Since no monosomic and nullisomic series are available in any Japanese variety, Norin 10 and Shinchunaga have been backcrossed several times to Chinese Spring monosomics. Completion of their monosomic series is expected in a near future. Several nullisomics are already obtained and compared with those of an American variety, Wichita. At this moment no remarkable difference was detected between them. (iv) Cytoplasmic differentiation - Six varieties of both Japan and U. S. A. were crossed in diallel combinations. These F1 hybrids will be backcrossed in order to obtain reciprocal nucleus-substitution lines. 3. Radiological study - Up to date, the investigation is limited to the radiological characterization of some representative wheat species. Einkorn, emmer, timopheevi and common wheat, including wild and cultivated forms, were grown in gamma-greenhouse. Einkorn wheat was the most sensitive under chronic irradiation, while the other three groups of wheat were not remarkably different from each other. 4. Morphological study - Using a number of strains or varieties of Asian or American origin, morphological investigation has been undertaken in order to identify their "taxonomic " variety. In Japan erythrospermum and ferrugineum races predominate over all the other races, while in America graecum and erythrospermum are common. |
| <-- Back | | | --> Next |