The effects of Ur-1 (Undulate rachis), Dn-1 (Dense panicle), Iax (lax panicle), sp (short panicle), Cl (Clustered spikelets) and ri (verticillate rachis) were investigated. Ur-1, Dn-1 and Cl are incompletely dominant genes, while lax, sp and ri are recessive genes. F₂ populations between one cultivar, Ishikari and 6 Iines carrying the respective 6 major genes, and the isogenic lines of Ur-1 and Dn-1 of another cultivar, Shiokari were used. It is inferred that Ur-1 increases the number of spikelets per panicle due to the increases of the number of secondary branches per primary branch and the number of spikelets per secondary branch, but decreases the number of panicles per plant, 100 kernel weight and spikelet fertility. In the F₂ of Ishikari×N-55 containing Ur-1, the Ur-1/Ur-1 and Ur-1/+genotypes were higher than the +/+ genotype in the perventage of panicle weight, but the difference among the three genotypes in panicle weight per plant was not significant. Dn-1 increases the number of secondary branches per primary branch and the number of spikelets per panicle, but decreases lengths of panicle, primary branch and secondary branch. Lax decreases the number of spikelets per primary branch and the number of spikelets per secondary branch, resulting in decrease of the number of spikelets per panicle. sp decreases all of the four components of the number of spikelets per panicle, viz. the number of primary branches per panicle, the number of secondary branches per primary branch, the number of spikelets per primary branch and the number of spikelets per secondary branch. Cl reduces length of secondary branch. ri acts to form the characteristic panicle that two to 10 primary branches grow verticillately from a few points on the panicle axis.

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Plant regeneration from cotylendon protoplasts of tomato (Lycopersicon esculentum cv. Kyoryokutoko) was obtained by somatic embryogenesis. Protoplasts were isolated from cotyledons of 8-10 day old in vitro-grown seedlings raised in a controlled chamber (20 °C, 3, 000-4, 500 lux, 16h). During initial protoplast culture, the addition of TM-2 medium (Shahin 1985) containing 0.15M sucrose, at 4 day intervals (sucrose concentrations were progressively reduced, 0.2M-0.17M-0.16M), resulted in vigorous cell divisions and prevented the browning of the cells. Somatic embryogenesis was induced from up to 50% of selected greenish calli when cultured on TM-4 medium supplemented with 2.0 mg/l zeatin riboside. Multiple adventitious shoots were formed by clonal propagation of somatic embryos on TM-4 or Murashige and Skoog (1962) medium containing 1.0 mg/l zeatin and 0.1 mg/l indoleacetic acid. Ninety-eight regenerated plants obtained from rooting shoots on Murashige and Skoog medium (0.8% agar, 20 g/l sucrose) were grown to maturity.

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The genes for red seed coat of wheat are known to have a relationship to tolerance to preharvest sprouting. We developed a method for extracting seed coat pigments controlled by the genes for red seed coat. Wheat cultivars used in this study were subjected to analysis of the genes for red seed coat prior to chemical analysis. The genotypes of Norin 66 and Fukuwasekomugi were identified as r1, R2, r3. Those of Norin 10 and Asakazekomugi were identified as R1, R2, r3. Those of Kitakamikomugi, Fukuhokomugi and Norin 61 were identified as R1, r2, R3, r1, R2. R3 and R1, R2, R3, respectively. Seed coat pigments were extracted from twelve cultivars (nine with red seed coat and three with white seed coat). The seeds were milled and the prepared bran was washed with hexane, acetone and diethyl ether to remove carotenoid pigments. The defatted bran was heated with 1M sodium hydroxide at 100°C for 30 min. The pigments were extracted with n-butanol after the pH of the solution was adjusted to acidic condition. The absorbance of the butanol extracts was determined at the region from 380 nm to 550 nm. The absorbance became higher as the number of the genes for red seed coat increased. The results showed that red seed coat pigments were extracted with these procedures.

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The soybean [Glycine max (L.) Merr.] Iine B739 has the high linolenic acid content in its seed oil. This line was identified from Bay in a mutation breeding program conducted in 1985 at Saga University. The objective of this study was to determine the genetic control of the high linolenic acid content in B739. The line B739 was crossed reciprocally with Bay. There was no maternal and cytoplasmic effects for linolenic acid content in these crosses. For total oil content, no maternal and cytoplasmic effects were also observed. The linolenic acid of F₂ plants of B739 X Bay was segregated in bimodal pattern into normal and high contents which satisfactorily fitted to a 3:1 ratio. This result was consistent with segregation of major gene at a single locus. The allele in B739 was designated lin^h and the genotype for B739 as lin^hlin^h and for Bay as LinLin. The oil content of F₂ plants had an inverse relationship with linolenic acid and when the oil was segregated in bimodal pattern into normal and low contents which satisfactorily fitted to a 3:1 ratio. Thus, it was assumed that the low oil content in B739 was also controlled by this allele. However, Iinolenic acid is the major component in the diet for some mammals, and consequently this allele would be effective to improve the lines with high linolenic acid content.

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This experiment was carried out to study the relationship between heterosis and the polymorphism of genetic markers in rice. We employed 14 varieties, 4 japonica, 4 javanica and 6 indica. Of all the 91 possible combination, one indica × indica cross was missing, so 90 F₁ cross combinations were used for half diallel analysis. They were transplanted in a field at 40 × 60 cm spacing and the top part of the plants was sampled and dried 43 days after transplanting to examine the degree of heterosis of biomass. The diallel analysis of the heterosis of biomass showed that dominant effect was larger than additive effect, suggesting that heterosis was contributed by the accumulation of dominant genes. More than 10 genes were considered to be involved in the heterosis. The general combining abiliy of biomass was highly significant and the heterosis of hybrids from crosses between indica and japonica varieties were generally large. Significant relationships were observed between the heterosis of biomass and the polymorphism of the 10 isozymes as well as 29 RFLP markers. However, the correlation coefficients were not so high. It seemed to be difficult to use the polymorphism of markers as an index of heterosis. The analysis of each marker and heterosis showed that several markers which were located dispersedly over the chromosomes showed significant correlations with the heterosis of biomass. According to the diallel analysis, more than 10 genes were related to the heterosis of biomass. Hybrids between indica varieties which have biomass controlled by dominant genes and japonica varieties which show over-dominance in crosses with indica are promising for breeding hybrid varieties with high biomass coupled with high yielding.

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A B-chromosome of rye (Secale cereale L.) found in the Japanese strain ‘JNK' was revealed to pair with one of the A-chromosomes. A spontaneous A-B chromosome translocation could be verified by pairing studies and testcrosses to defined trisomics and wheat-rye addition lines. They showed that the long arm of rye chromosome 3R is involved in the rearrangement. Obviously, a terminal segment, including a large terminal heterochromatin block, was transferred to the terminal region of the long arm of the B-chromosome. A possible relationship between the interchange and the origin of the B chromosome is discussed.

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F₃ Iines of the hybrids of some varieties and Japanese susceptible varieties were tested with two Japanese blast fungus strains, Ken 54-20 (race number, 003.0) and Ao 14-20 (337.3), to learn the mode of inheritance of blast resistance. Varieties used were as follows : Chinese varieties (Sifeng 43, Quan-wei-ai and Nan Jing 11), Korean varieties (Milyang 23, Raekyeong, Ir 338), IRRI's varieties (IR 24, IR 36 and IR 2061), Indian varieties (RP 9-3 and CR 44), and Hokuriku 129 (Habataki). Analyses after tests were carried out by cumulative frequency distribution curve method by Kiyosawa. In this study, plants were divided into three groups, r, m and s, based on the degree of resistance, and resistance genes were divided into two. One was the major gene which had a functional value of 1 and the other was the minor gene which had a functional value lower than 1 in a segregation of r : (m+s). The functional value of 1 means that plants which had its genotype show resistant reaction in 100 % of plants. The resistance of these varieties was explained by assuming some major genes and minor genes. Sifeng 43 has one major gene and one minor gene. Quan-wei-ai and Nan Jing 11 have two minor genes with their additive (or complementary) effect. It was suggested that there are minor genes controlling resistance in intermediate type (m) in Milyang 23, Raekyeong, Iri 338. IR 24 and IR 36. IR 2061 has two or more major genes and some minor genes. Resistance of Hokuriku 129 was explained by two major genes. At the least, Milyang 23, Raekyeong, Iri 338, IR 24, IR 36 and CR 44 were suggested to have Pi-b.

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We previously proposed a new breeding scheme to develop hybrid wheat cultivars utilizing male sterility caused by the interaction between an S^v type cytoplasm and a 1BL-1RS chromosome (Toriyama et al. 1993). After this proposal, 13 Japanese cultivars were used to develop male-sterile lines and their maintainers. The donor of the S^v type cytoplasm of Ae, kotschyi was (S^v)-Norin 26, and the donor of the 1BL-1RS chromosome was 911-B-8-1O (abbreviation, st. 911). (S^v)-Norin 26 and st. 911 were repeatedly backcrossed with the 13 cultivars (cv. A is used to generalize a description). Then, the S^v cytoplasm-substituted lines [(S^v)-A] and the 1BL-1RS chromosome-substituted lines [mt. A] for 13 cultivars were developed as reported in our previous paper (Nonaka et al. 1993). During their breeding process, we observed the following phenomena other than the dose effet of the Rfv1 gene on restoration for pollen fertility. (i) Effects of the S^v cytoplasm on agronomic traits were negligible except on 1, 000 grains weight which may be compensated on grain yield by heterosis in F₁ hybrids. (ii) Significant differences in some agronomic traits were observed between mt. A Iines and their original cultivars, though the effects of these differences on yield of F₁ hybrids were not investigated. (iii) The pollen carrying the 1BL-1RS chromosome was inferior to the pollen carrying the 1B chromosome in gametic selection. (iv) Some mt. A Iines showed insufficient pollen shedding caused by non-opening or incomplete opening of glumes at flowering time. (v) Newly developed mt. A Iines had resistance to powdery mildew in addition to leaf rust. And, (vi) Male-sterile lines [ms(S^v)-mt. A] and mt. A Iines had white glume color instead of brown glume color of the original cultivars used.

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In order to transfer the growth habit and the resistance to Pseudomonas solauacearum from S. sanitwongsei to S. melongena, electrofusion was carried out. The fused protoplasts were cultured in KM(8p) medium supplemented with 1, 000ppm wilt-inducing product secreted by a virulent strain of P. solanacearum. The regenerated plants were further screened on the soil contaminated with P. solanacearum. Only one plant survived. Several morphological traits of the surviving plant were intermediate between those of the parents, and the chromosome number was 48. The pollen viability averaged 82.3%, and fruits were set. The hybridity was confirmed using random amplified polymorphic DNA (RAPD) markers. The somatic hybrid exhibited a resistance to P. solanacearum comparable to that of S. sanitwongsei. The juvenile growth of the offsprings (S1 plants) obtained by selfing of the somatic hybrid was superior to that of S. sanitwongsei. The S1 plants were also as resistant to P. solanacearum as S. sanitwongsei. When the S1 plants were used as rootstocks for eggplants, the fruit yields were as high as those of eggplants grafted on S. sanitwongsei. It was considered that the S1 plants could be used as rootstocks for eggplant production.

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To elucidate the cross-compatibility among 9 species of genus Fagopyrum, the pollen tube growth in intra- and interspecific pollination was investigated. 120 pollination treatments were conductcd under screen house conditions in their fully flowering stage. Florets were harvested 4 hours after pollination, and pollen tubes were viewed on a fluorescent microscope. Measurements of pollen tube length were made on the longest pollen tube per style and 6-30 styles were observed per pollination treatment. The pollen tubes of F. esculentum and F. cymosum grew similarly in their reciprocal pollination, and the pollen tubes of thrum in crosses among F. Ieptopodum. F. capillatum, F. pleioramosum. F. urophyllum and F. callianthum showed satisfactory growth. Besides, the pollen tubes of F. tataricum in the style of F. esculentum and F. cymosum grew satisfactory as well as the self pollination of F. tataricum, in contrast, the pollen tubes of F. gracilipes were inhibited in the styles of F. esculentum and F. cymosum. When F. tataricum was used as a female parent, the pollen tube in all of the 8 interspecific crosses could penetrate into the micropyle. It is clear that there was a close re-lationship between the PL : SL ratio and the frequency of pollen tube reaching the ovary. Accordingly, it is suggested that the combinations showing high pollen tube growth in this interspecific crosses have a high potential of interspecific cross-compatibility. By cluster analysis based on the similarity of pollen tube growth, the species of Fagopyrum can be classified into two groups.

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In order to establish a cell culture system free from somaclonal variations, somatic embryogenesis and plant regeneration from immature tassel segments were observed in heterozygote (D8/+) of dwarf maize. The immature tassels (0.5-3 cm) were excised, cut into segments (1-2 mm), and placed on to Murashige and Skoog(MS) medium containing low concentration of 2, 4-dichlorophenoxyacetic acid (2, 4-D) 1 ppm and 3 % sucrose. After 3 weeks the segments were transplanted to medium containing 2, 4-D 1 ppm and kinetin 0.1 ppm to promote callus growth, which produced compact, nodular, white embryogenic callus. Embryogenic callus further developed somatic embryo via green spots with distinct scutellar and coleoptile-like structures, which produced normal, fertile plants with no apparent morphological abnormalities. Maximum embryogenic callus formation was observed when the callus was placed on to media containing 0.1 ppm NAA and 1 ppm kinetin. In order to explore gibberellin response of dwarf genotype (D 8/+), the compact white calli were cultured in defined solid media containing different concentrations of gibberellic acid (GA₃) and indole-3-acetic acid (IAA). The response of heterozygote (D 8/+) in the BC₂ of ‘Okuzuru' genotype (B₂0) suggested that the dominance dwarf gene, D₈ did not response to GA₃ in cultured cells as well as in intact plantlets. The growth rate (RGR) of dwarf heterozygous (D 8/+) callus was significantly lower than that of tall homozygote ( +/+ ). Principal component analysis (PCA) for three morphological characters, (plant height, tassel length and leaf width) of regenerated plants revealed that the regenerated plants almost kept morphological normalities of the explant genotypes. But the class of explants often affect morphology of the regenerated plants. The use of immature tassel as explants permits selection of specific baenotypes via genetic markers or particular plant phenotypes prior to culture initiation. By using this cell culture system, plant breeding program for maize will save a lot of labour and time in the experimental fields.

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The shattering resistance in five mutant lines was found to be controlled by a single recessive gene. The analysis was carried out using the F₁, F₂ and F₃ populations that were derived from the reciprocal crosses between five mutant lines and the oritginal variety, Nan-jing 11. The allelism test using the twenty F₂ populations bred by the reciprocal crosses among five mutant lines, indicated that 1) the three mutant genes of SR-4, Hokuriku143 (SR-5) and SR-6 were located at the same locus, 2) the genes of SR-1, SR-2 and these three lines were located at different loci. The classification of the five mutant lines by their mutant loci coincided with the shattering degree and the formation of abscission layer. The SR-1 group showed a high shattering resistance without abscission layer. SR-2 group was moderately resistant to shattering with the presence of slightly decayed cells in the region between the rudimentary glumes and sterile glumes in a spikelet. The last group consisting of SR-4, SR-5(Hokuriku143) and SR-6 was resistant to shattering with cells displaying a higher level of decay than in the case of SR-2. These five mutant genes were classified into three groups in relation to the formation of abscission layer. It was also assumed that the original shattering gene(s) in Nan-jing 11 that was/were partial dominant was/were involved in the formation of the abscission layer or shattering degree, since the shattering degree and the formation of the abscission layer in F₁ plants were intermediate between those of the parents. These results indicate that Nan-jing 11 harbours three partial dominant genes related to the formation of the abscission layer and/or shattering habit.

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Hybrid plants between N. suaveolens and N. tabacum plants exhibit lethality under standard culture conditions and die at the cotyledonary stage. For overcoming this type of high brid lethality, the effect of cytokinin was tested. The intact hybrid seedlings were cultured on media containing cytokinin (0-10mg/l kinetin or 6-benzylaminopurine (BAP)).Adventitious buds were regeneratcd from the base of the hypocotyl or the primary root of the dying seedlings. The regenerated shoots were transferred to the medium containing 2mg/l 3-indoleacetic acid (IAA) to accelerate rooting. The hybrid seedlings maintained a vigorous growth without developing any lethal symptoms up to maturity in a greenhouse. Forty chromosomes were counted in their somatic cells and their morphological characters were intermediate between those of parental species. Intact seedling culture with the addition of cytokinin was found to be a very simple method for overcoming lethality in this cross-combination.

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