The Japanese Journal of Genetics

Cytogenetical studies on the genus Oryza.

XIII. Relationship between the genomes E and D

Taira KATAYAMA

1982 Volume 57 Issue 6 Pages 613-621
Published: 1982
Released on J-STAGE: July 25, 2006

DOIhttps://doi.org/10.1266/jjg.57.613

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To clarify the relationship between E genome of Oryza australiensis and D genome of CCDD genome species, F₁ hybrids of O. officinalis (CC)×O. australiensis (EE), CE plant×CCDD genome species and amphiploid CCEE× CCDD genome species were studied. CE plant was morphologically similar to O. australiensis than to O. officinalis, and the F₁ hybrids of CE plant×CCDD genome species and of amphiploid CCEE×CCDD genome species were similar to the CCDD genome species. Somatic chromosome numbers in the F₁ hybrids of CE plant×CCDD genome species ranged from 46 to 72. Those of the hybrids of O. officinalis×O. australiensis and amphiploid CCEE×CCDD genome species were 24 and 48, respectively. At MI chromosome differences in size were observed in the F₁ hybrid of O. officinalis×O. australiensis. Number of bivalents at MI of the F₁ hybrids having 48 chromosomes (2n) obtained from the cross between CE plant and CCDD genome species ranged from 15 to 23 with a mean of 18.2 (CES-4) to 19.9 (CES-15), while that from the cross between amphiploid CCEE and CCDD genome species ranged from 8 to 24 with a mean of 17.6 (C-1) to 20.9 (B-1). The above results suggest that the genomes E and D may be closely related.

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Population genetics of cultivated common buckwheat, Fagopyrum esculentum Moench.

I. Frequency of chlorophyll-deficient mutants in Japanese populations

Ohmi OHNISHI

1982 Volume 57 Issue 6 Pages 623-639
Published: 1982
Released on J-STAGE: July 25, 2006

DOIhttps://doi.org/10.1266/jjg.57.623

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In order to reveal the amount of concealed genetic variation maintained in cultivated buckwheat populations, the frequency of chlorophyll-deficient abnormalities per gamete was estimated by conducting more than 3000 full- sib matings. The following types of abnormalities were observed in the cotyledons; albino (0.37%), yellow (3.56%), pale yellow (4.86%), pale green (7.40%), variegated (2.39%) and morphological (2.04%). Each type was also found in the foliage leaves at about a half the frequency in the cotyledons. The total frequency did not vary so much among the populations, ranging from 18.0 to 34.5%, with the exception of the Togakushi population, which had a low frequency. A significant north-south cline in the frequency was observed in fall type buckwheats. The frequency of abnormalities was also examined in randomly mating populations in farmer′s field and the total frequency was 0.020-0.072% in the cotyledons and 0.016-0.059% in the foliage leaves. The low frequency of homozygotes in randomly mating populations may be due to a large population size, panmixia by insect pollinations, and the virtual absence of inbreeding. Based on the estimated frequency per gamete and the estimated frequency in randomly mating populations, the number of loci affecting chlorophyll-deficiencies and the deleterious allele frequency per locus were estimated. The approximate number of loci was at least 70, probably close to 100, and the allele frequency was around 0.001-0.004, implying that the detrimental genes in buckwheat populations are maintained by mutation-selection balance.

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Population genetics of cultivated common buckwheat, Fagopyrum esculentum Moench.

II. Frequency of dwarf mutants in Japanese populations

Ohmi OHNISHI, Takayuki NAGAKUBO

1982 Volume 57 Issue 6 Pages 641-650
Published: 1982
Released on J-STAGE: July 25, 2006

DOIhttps://doi.org/10.1266/jjg.57.641

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Allelism tests among 15 independently established dwarf lines revealed that five loci are involved in dwarfism in common buckwheat. They are designated dwA, dwB, dwC, dwD and dwE. The frequencies of dwarf mutants at four loci, dwA, dwB, dwC and dwD were investigated in three Japanese populations, Iwate, Togakushi, Higashi-Iyayama, by using four representative homozygous lines as the testers. The frequencies varied slightly among the populations, but on the average they were 0.235%, 0.067%, 0.294% and 0.196% for the dwA, dwB, dwC and dwD loci, respectively. These low allele frequencies imply that the recurrent mutation is balanced by selection against the dwarf alleles. This conclusion was confirmed by supplemental data on the frequency of dwarf mutants per gamete and a field survey of dwarf homozygotes in randomly mating populations in farmer′s field. Approximately 0.50% of the gametes contain a dwarf allele, whereas the incidence of dwarfism in the randomly mating populations was only 4.25 ×10^-6. The latter estimate was based on a study of more than 3 million plants.

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Non-DNA-replicative setting of guard cells in Spinacia oleracea L.

Ryuso TANAKA, Soryu NISHIBAYASHI

1982 Volume 57 Issue 6 Pages 651-655
Published: 1982
Released on J-STAGE: July 25, 2006

DOIhttps://doi.org/10.1266/jjg.57.651

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Nuclear DNA content in the guard cells and epidermal cells of Spinacia oleracea L. was measured using Feulgen microspectrophotometry. Guard cells in leaf blade, cotyledonary leaf and hypocotyl retained a constancy of 2C DNA value. On the contrary, epidermal cells had 2C, 4C and 8C DNA value in both leaf blade and cotyledonary leaf, and 2C, 4C, 8C and 16C in hypocotyl. With regard to DNA content, it may be considered that the guard cells are set up in a non-DNA-replicative state, while the epidermal cells in an endopolyploidal DNA-replicative state.

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