We attempted to analyse the mechanism of cytoplasmic male sterility (cms) in two strains of rice, that is, cms-Bo Taichung 65 with cytoplasm of cultivar Chinsurah Boro II and cms-R Reimei with cytoplasm of a strain of Oryza rufipogon. Mitochondrial DNAs (mtDNAs) were purified from cms and fertile (normal) rice varieties and the electrophoretic pattern of their restriction fragments was compared. MtDNA purified from cultivar Chinsurah Boro II cytoplasm contained two plasmid-like low molecular weight DNAS and the pattern of the restriction fragments of mtDNA from Chinsurah Boro II cytoplasm was clearly different from that of the normal cytoplasm. Plasmid-like DNAs have not been detected yet in the mtDNA from a strain of Oryza rufipogon cytoplasm but the pattern of the restriction fragments of mtDNA was also obviously different from that of the normal cytoplasm. Moreover the pattern of the restriction fragments of mtDNAS from a strain of Oryza rufipogon and Chinsurah Boro II cytoplasms was clearly different. In contrast, the pattern of the restriction fragments of chloroplast DNAS from normal and cms cytoplasms of Taichung 65 or Reimei was identical. We speculate that the difference in the mitochondrial genome between cms and normal 'cytoplasms of Taichung 65 or Reimei is, at least partly, responsible for the occurrence of cms.

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A comparative study of variability in the wild Camellia sasanqua was conducted in 69 study sites covered the majority of the natural populations of the species in Japan. Less-disturbed broad-leaved evergreen forests within the study sites exhibited canopy trees of C.sasanqua up to 1Om in height, up to 46cm in DBH (trunk diameter a.t breast height) and average 125 years in age, while well-disturbed forests of either coppice forests or afforested plantations exhibited mostly sapling trees of C. sasanqua up to 2m in height, up to 2cm in DBH and average 10 years in age, which had large stumps up to 75 cm in diameter. All of the plants from the study sites had the same chromosome number of 2n=90 (hexaploid). The burried seeds of the seed bank have never been long-lived and stored for more than a year. Seed germination, recruitment and plant growth of more open habitats, plentifully supplied with light were expected to allow many more modules to develop. However, the seedlings appeared in low relative light intensity of 12.1% br less suffered a constant probability of death within the frst two years. Signficant correlations were seen between mean leaf length and mean petal length, between mean leaf width and mean petal width, between mean leaf area and mean petal area, between mean leaf length and mean leaf width, and between mean petal length and mean petal width. Nevertheless, those quantitative variations in leaf and flower-petal could not be correlated with differences in habitats. Only four variant forms found were as follows: (1) semi-double flower form of a bud variation in the study site No.6, (2) pinkish-white flower form in the study site No.20, (3) larger petal form in the study site No. 64, and (4) deeply crenate-margin leaf form in the study site No.69. No hybrid was seen in cross-combination between the wild C.sasanqua and its cultivars or other sympatric species which were not seasonally isolated. Since the present wild C.sasanqua was highly adapted to morphological uniformity and quantitative constancy and showed no segregation of morphological and quantitative characteristics, it could involve rarely with cultivar occurrence.

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Effects of colchicine used for chromosome doubling of haploid plants were examined as a possible cause for the genetic variation among anther-derived doubled haploid lines of an inbred tobacco (Nicotiana tabacum L.). Colchicine induced doubled haploid lines (C-DH) and spontaneous doubled haploid lines (S-DH) were developed and their agronomic traits were compared with those of the selfed lines of the parental plant used for the anther culture. S-DH exhibited as great quantitative variability within the family as C-DH did. In each case, the direction of the changes was towards low productivity ; reduction of plant height and leaf size. Some doubled haploid lines were revealed to have nornicotine, another type of the alkaloids, whereas all of the selfed lines of the source plant for anther culture had normal nicotine as the major alkaloid. This change in the alkaloid type was found in the plantlets before the colchicine treatment was applied. In addition, colchicine treatment of seed-derived diploid seedlings did not produce the nornicotine-type plantlets. These findings indicate that the colchicine treatment contributed little to the genetic variation of doubled haploid lines.

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The crossabilities between Japanese wheat cultivars (Triticum aestivum L.) and tetraploid clones of Hordeum bulbosum L. were examined. In particular the effects of chemical agents on wheat crossability for improving crossing procedures in wheat haploid production were investigated. Twenty-two of the thirty-two wheat cultivars examined were crossable at frequencies of 10.4%-45.9% seed set. These crossable cultivars are genealogically derived from the progenies of crosses between Japanese local cultivars. The H.bulbosum genotypes used as pollinators also greatly influenced seed setting on wheat cultivar Fukuhokomugi with frequencies of 4.1%-50.0%However, non-crossability of Haruhikari could not be satisfactorily overcome when pollinated with the most promising clone of H. bulbosum. Crossing procedures with application of 2, 4-dichlorophenoxyacetic acid prior to pollination greatly increased seed setting on Fukuhokomugi, but did not appear to reduce effectively the incompatibility of Haruhikari. The present results suggest that this technique can be adopted to improve wheat haploid production using the bulbosum technique when crossable wheat genotypes are used as starting material.

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Complete autotetraploid plants in three monoembryonic diploid citrus cultivars ('Clementine', 'Hassaku' and 'Hyuganatsu') were produced successfully from small young axillary buds isolated and immersed in 0.1% colchicine solution for 2-6 hours by using the micrografting technique. The induced tetraploidy was associated with the presence of broader and thicker leaves, larger stomata and flowers. Moreover, thorns were produced on the elongating shoots of all the induced tetraploid plants. The signiflcance of this thorniness for the detection of tetraploidy in citrus after colchicine treatment is discussed.

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Isozymes of GOT and MDH in leaves of 105 citrus biotypes were analyzed using acrylamide gel electrophoresis. At least 3 loci were detected on these two enzymes. From the analysis, Natsumikan (Citrus natsudaidai), Hassaku (C. hassaku) and some other citrus cultivars are considered to be hybrids of pummelo (C.grandis) and mandarin as suggested. Moreover, Iyo (C.iyo), which has been assumed to be a hybrid of sweet orange (C.sinensis) and mandarin, was found to have a genetic effect from pummelo. Sour oranges (C.aurantium) had unique allele A at Got-1. In addition to the sour orange, the same allele was found only in lchang lemon (C.wilsoni), Bergamot (C. bergamia) and 'Hirado' pummelo. While, Tachibana (C.tachibana), Shiikuwasha (C. depressa), and Korai-tachibana (C. nippokoreana), which are reported to be native to Japan and its neighboring areas, had an unique allele A at Got-2. This allele was also found in Hyuganatsu (C.tamurana) and some biotypes originated in Japan, but not found in mandarins originated in mainland China, India, Philippines and other areas. While, Yuzu (C.junos) and its relatives had B at Got-2 and B at Mdh-1.

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Eight hundred and fifty soybean accessions were screened for genotypes with electrophoretic variations of the β-conglycinin and glycinin subunits. We detected two abnormal SDS-gel electrophoretic forms of β-conglycinin α-subunit, the slow electrophoretic mobility type designated as α-slow-type and the low α-subunit content type designated as α-low-type. Each of these two forms was controlled by a codominant allele at a single locus. The gene symbol Cgy2a was assigned to the common type and Cgy2b to the α-slow-type. We found a new electrophoretic form of β-conglycinin β-subunit designated as β'-subunit which migrates slightly faster than the β-subunit on SDS-gels. Beta-prime (β') subunit was controlled by a single dominant gene designated as Cgy3. The homozygous recessive cgy3 cgy3 lacked the β'-subunit. We observed two variations of the glycinin group-I acidic subunits (A1, A2 and A3) by alkaline urea electrophoresis, i. e., the concomitantly slow and fast electrophoretic mobility types designated as A(I)-slow-type and A(I)-fast-type, respectively. The concomitantly slow and fast migrating Al'A2 and A3 subunits, respectively, behaved in the F₂ seeds as a single block composed 'of the three electrophoretic bands. Each of these electrophoretic forms was inherited as if controlled by a codominant allele at a single locus. The gene symbols, Gyla, Gylb and, Gylc were assigned to the alleles for the common electrophoretic type, the A(I)-slow-type and the A(I)-fast-type, respectively. Close linkage was found between Cgy2 and Cgy3. The gene Cgy1 controlling the β-conglycinin α'-subunit was independent of Gy1 and Gy4 which controls the A5 subunit and its associated basic subunit.

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Genetic analyses have been carried out for male sterility of artificial mutants induced by the gamma ray of 60Co or the chemical mutagen ethylene-imine (Table 1). Observation of pollens of male-sterile lines vegetatively propabaated by dividing tillers revealed that there were three types of pollen degeneration. They are no pollen type which does not produce any pollen grains in an anther and most frequently appeared, non-stained pollen type which produces abortive pollen grains not stained by the solution of iodine-potassium iodide and occurred with fairly high frequency, and stained pollen type with apparently normal pollen grains which appeared less frequently (Table 2). Most mutant lines were completely sterile under bagged self-pollination but three lines were partially (3 to 14%) self-fertile. When male-sterlle plants of mutant lines were pollinated with normal pollens of another glutinous cultivar, all mutant lines showed normal seed set suggesting that female organs were not spoiled and that sterility of these lines was caused by male sterility.

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Inbreeding coefHcients (F) in sweet potato breeding materials were computed and the relationship between yield and F value was studied. The purpose of this study was to determine how high F value was tolerable for high-yeild breeding because it is now practically impossible in sweet potato breeding to make crosses between parents having no common ancestors in their pedigrees. Yield data were from the yield tests of seedling clones for 20 years. F values of 890 breeding materials were computed. The number of ancestors and the maximum generation in each pedigree were counted to give the outline of the pedigree. The number of ancestors in a pedigree (number of cultivars in a pedigree tree) was counted by two methods : one method (total number of ancestors) involved counting total ancestors, i.e., counting twice when one cultivar appeared twice and counting three times when it appeared three times in a pedigree. The other method (number of ancestors "except common ones") counted a cultivar only once even though it appeared more than once in a pedigree. Maximum generation in a pedigree means, for example, when the "last" ancestor is a grandparent. it is 2, and when the last ancestor is a grat-grandparent, it is 3.

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The immature leaflets (simple leaves) from 3 and 9 days old seedlings of azuki bean formed two types of calli (soft and compact) on the medium containing MS's major and minor salts and vitamins as in the B5 medium, with the addition of 500mg/l casamino acid and various combinations of NAA and BA, but they did not regenerate shoots even after 90 days of culture. On the other hand the compact calli induced on the medium containing 0.5mg/l NAA+2.0mg/l BA differentiated shoots after three subcultures at 30 day intervals on the medium containing 0.2 mg/l BA.

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This is the first report to show possibility of overcoming hybrid inviability in the cross between N.repanda and N.tabacum using the egg cell irradiation technique. Pistils of N.repanda before anthesis were planted onto solid medium in petri dishes, and were exposed to gamma-rays before pollination with N.tabacum pollen grains. On the 4 th, 5 th, 6 th days after the cross-pollination in vitro, the developed ovules were inoculated on the fresh solid medium. Two of the obtained seedlings reached to maturity in greenhouse. They were hybrid plants having 46 and 48 chromosomes respectlvely.

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Somatic embryos and plantlets were induced from suspension culture of cotyledon callus in melon (Cucumis melo L.). Cotyledons excised directly from bared mature seed were cultured on MS agar media with several concentrations of 2, 4-D and BA. Three weeks old calli were transferred to MS liquid medium without growth regulators, and cultured on a reciprocal and gyratory shaker (115 rpm). Somatic embryos and plantlets were observed within 2-3 weeks in the liquid media. The calli cultured on MS agar medium with 1.0mg/l 2, 4-D+0.1mg/l BA were the most suitable for embryogenesis.

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Hybrid strains of Pleurotus ostreatus were produced by intraspecific protoplast fusion crf auxotrophic mutants derived from monokaryotic strains. Auxotrophic mutants were obtained by treating fragmented mycelia by N-methyl-N'-nitro-N-nitrosoguanidine. One of them obtained from 241 ss 8 strain required uracil for growth on minimal medium, and another one obtained from 235 pSA strain required methionine. After fusion of mixed protoplasts of these two auxotrophic mutants by polyethylene glycol, many colonies were formed on a plate containing minimal agar medium. By isolating those colonies, several dikaryotic strains were obtained. They were cultured in sawdust-rice bran medium at 25C. After transfering into a condition alternating in temperature and light condition in cycle, fruit bodies were formed. Color of the fruit body was gray which was the similar color to one of the parent FMC 241, while the temperature for primordia formation of those fruit bodies was similar to the other parent FMC 235. Thus, the hybrid strain had the characteristics of both parents. Analysis of esterase isozyme pattern also showed the hybrid nature.

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