Experiments were carried out to analyse the inheritance of the flower color, especially carotenoid pigmentation, in chrysanthemum. Such as determination can be performed easily by measuring the amount of light transmitted in fresh, intact petals, using spectrophotometry regardless of the presence of carotenoid pigments in the petals. Based on the results of the genetic background analysis of the inheritance of carotenoid pigmentation, chrysanthemum cultivars used in this experiment were classified into three groups. In the first group a heterozygous dominant inhibitor genes for carotenoid pigment biosynthesis was identified while in the second group no such dominant inhibitor gene was present and in the third group the gene constitution was complex and characterized by the presence of a heterozygous dominant inhibitor gene and heterozygous dominant gene for carotenoid pigmentation. The wild species, Chrysanthemum japonense, was different from the chrysanthemum cultivars used in this experiment in that species harboured a homozygous dominant inhibitor gene at least a single locus. Therefore, in all the F₁ progenies derived from the crossing of this species with several varieties no plants with yellow flowers were observed. Moreover, it is suggested that a chimerical strucrue should be considered in analyses of the flower color inheritance.

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Isozyme variation found in leaf tissues of hinoki, Chamaecyparis obtusa, were investigated using polyacrylamide vertical slab gel electrophoresis. Twelve enzyme systems were examined in selfed and crossed families to detect marker genes, and electrophoresis banding variants for 10 of the 12 enzyme systems were observed. Judging from the segregation data, 14 Ioci were identified. The genetic variation of three populations of two natural forests was surveyed using these isozyme loci. The average proportion of polymorphic loci (95 % criterion) was 56.4%, the mean number of alleles per locus was 2.00, and the mean expected heterozygosity was .228. The results of the gene diversity analysis and genetic distance indicated these populations are differentiated little from each other.

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The CMS trait of petaloid-type flowers in carrot was tried to transfer to fertile varieties by donor-recipient protoplast fusion. X-irradiated protoplasts of the carrot CMS line, 31A, and iodoacetamide-treated protoplasts of 5 different fertile varleties were used as a cyioplasmic donor and recipients, respectively. Fifty-eight plants were regenerated from the fusion experiments and no plant with petaloid flowers was observed. A11 the regenerated plants were fertile or male sterile with brown anthers. To produce cybrlds with petaloid-type flowers, Z1, which is a regenerated plant obtained from protoplast fusion between 31A and K5, was used as a cytoplasmic recipient and fused with X-irradiated protoplasts of 31A. From this donor-recipient protoplast fusion, 41 fusion products were regenerated and bore flowers. Among them, 39 plants were CMS with petaloid stamens and 2 plants were the same male sterile with brown anthers as Z1. Chromosomal and mitochondrial DNA analyses of the fusion products revealed that all of the plants investigated had nuclei derived from Z1 and rearranged mtDNAs. After crossing with fertile varieties including K5, the petaloid male sterility of the fusion products was maternally inherited in the F₁ and F₁B₁ generations. Other agronomic traits of the progenies were similar to those of the parental fertile line. The results indicate that the petaloid CMS trait can be transferred effectively to another carrot line by using two-step donor-recipient protoplast fusion.

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Genic control of tolerance to chilling injury at the seedling stage in rice was analysed under the temperature treatment of 5°C for 4 days. All the F₁ plants in reciprocal crosses between tolerant and sensitive varieties were tolerant. Tolerant and sensitive plants were segregated in the F₂ generation. The F₂ segregation fitted well to the ratio of 3 : 1 . Three genotypes, tolerant homozygotes, segregating heterozygotes and sensitive homozygotes were segregated in the F₃ lines derived from selfed F₂ plants with the ratio of 1 : 2 : 1. These results indicate that the tolerance to chilling injury is controlled by a single dominant gene designated as Cts2(t). The linkage relationship between the chilling injury and low temperature chlorosis was studied using the same F₂ populations. Normal and chlorotic seedlings were segregated in the F₂ populations with the ratio of 3 : 1, but no linkage relationship between the chilling injury and low temperature chlorosis was found, indicating that both the tolerances are controlled by different loci.

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C0₂ gas was supplied at a high concentration (3-5%) to the tissue culture chamber and its effect on shoot regeneration was examined in anther- and seed-derived calli of rice (Oryza sativa L.). The applicaiton of C0a₂ was effective in both shoot and root regeneration. Furthermore, C0₂ supply reduced the necrosis of callus. When test tubes were capped with porous film in stead of aluminum foil, the regeneration rate was increased, in particular when C0₂ gas was supplied. Even when C0₂ was supplied, the addition of 3 % sucrose in the medium was more effective for the regeneration than 1% sucrose. By the C0₂ supply, plant regeneration was accelerated and the regenerated shoots became so vigorous that they could be safely and easily transplanted to soil.

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Malting qualities of eleven hexaploid triticale cultivars (X Triticosecale WITTMACK) with different chromosome constitution of R-genome, types of cyioplasm and winter/spring growth habit were evaluated by using micromalting trials. Cultivars with complete type for R-genome chromosomes had higher diastatic power, malt extract, and extract yield than those of the substitution type. Cultivars with Triticum aestivum cytoplasm used in this experiment had more number of R-genome chromosomes replaced by D-genome chromosomes, and they showed comparatively low diastatic power and extract yield in the malt. Higher diastatic power was found in cultivars with Triticum turgidum cytoplasm than with aestivum cyioplasm, while higher malt extract and extract yield were observed in cultivars with aestivum cytoplasm than with turgidum cytoplasm. Winter-type triticale, Lasko, showed much higher values in diastatic power, malt extract, extract yield and germination capacity than those of the spring-type triticale in this experiment. Generally, cultivars with complete type of R-genome chromosomes and aeslivum cytoplasm had higher malt extract, extract yield, and Kolbach index, and lower total nitrogen content than those with substitution type in R-genome chromosomes and turgidum cytoplasm. Total nitrogen content was assumed to correlate with the level of modification and enzyme activities of hexaploid triticale malt.

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Using inbred lines and their F₁ and F₂ populations of Brassica campestris, three isozyme loci for Acid phosphatase (ACP), Acp-3, Acp-4 and Acp-5, and two for Esterase (EST), Est-3 and Est-4 were identified by polyacrylamide gel electrophoresls. Out of ten possible pairs of the five loci identified, five pairs of loci were tested for linkage, and found to segregate independently. Acp-3 and Acp-5 were found to be useful to check genetic purity of seed in hybrid varieties. With the other three loci possessing null alleles it seemed difficult to distinguish dominant homozygotes from heterozygotes. Allelic frequencies at the five loci were estimated in 15 native varieties. Acp-5 and Est-4 showed remarkable segregation in almost all the varieties, while homozygous genotypes were observed in other loci. Two varieties of the 'Mizuna' group showed remarkable polymorphism in the EST zymograms suggesting that this varietal group may be different from other varietal groups.

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The degree of apomixis of six cultivars of Chinese chive (Allium tuberosum ROTTL.) (2n= 32, 4x) was estimated by electrophoretic analysis of leaf esterase (EST) in progenies obtained from crosses between these cultivars. In each progeny, more than 90% of the seedlings showed the same zymogram as their pistillate parent, the remaining seedlings showing hybrid zymograms. The differences between maternal and hybrid zymograms were clear and unmistakable. The degree of apomixis was therefore calculated to be higher than 90% for each cultivar tested. For two progeny arrays the results of the electrophoretic analysis were supported by simultaneous examination of two morphological traits, namely, outer tepal length and first flowering month. Among the seedlings showing the maternal EST zymogram, two dihaploids (2n= 17, 16), one each in two progenies, were detected by cytological examination of root tips. Those dihaploids being eliminated, the degree of apomixis estimated by the isozyrne analysis was reduced by 1% resp. 2% for these progenies. This modification, however, was of little significance because of the infrequent occurrence of dihaploids. The present results indicate that a progeny test exclusively based on the EST analysis gives only a slight overestimation of the degree of recurrent apomixis in Chinese chive and that Chinese chive is a facultative apomict wlth a high degree of apomixis.

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Somatic embryogenesis and plant regeneration were studied in 12 genotypes of the facultative apomictic species Panicum maximum Jacq. (Guineagrass). Embryogenic callus was initiated from immature embryos (0.5∼1.0mm long) on MS medium (MURASHIGE and SKOOG, 1962) supplemented with 10mg1^-1 2, 4-dichlorophenoxyacetic acid (2, 4-D), 10% coconut water and solidified with 0.8% Agar. Initially various types of callus were obtained and embryogenic responses were found to be correlated with the genotypes investigated. Somatic embryos could be induced from all genotypes except one, but varieties "Petrie" and "Gatton" appeared to have the highest embryogenic capacity among the twelve genotypes. For somatic embryo germination and plant formation MS medium supplemented with GA3 and cytokinins was used. The best response was observed with 1.0mg1^-1 GA3 and 1.0mg1^-1 kinetin. The twelve genotypes analyzed can be classified into three groups by the frequency of somatic embryo formation and the degree of apomixis. The first group consists of highly apomictic genotypes with a high embryogenic capacity-"Petrle" and "Gatton" The second group is composed of highly apomictic types with lower tendency to form somatic embryos- "Natsuyutaka" N68/84-1-s 6, N68/84-1-s 7 N68/84-1-o 6, N68/84-1-o 8 and N68/96-8-o 10. The third group is formed by types displaying a lower tendency both in apomixis and formation of somatic embryos-S67, N68/84-1, N68/96-8, N68/96-8-o 1.

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To obtain mutants deficient in nitrate reductase (NR) in rice, screening for chlorate resistance was carried out using the mutant lines maintained at the Institute of Radiation Breeding, NIAR, Japan. Of 437 lines tested, four chlorate resistant lines (M819, M821, M1004 and M1009) were selected. Differences in chlorate sensitivity were also observed among the four selected lines. The levels of in vitro NR activity of seedlings in M819 and M821 were below 30% of that of their parent, Norin 8. M819 and M821 were identified as low NR activity lines. NR activity in M1009 was about 80% of that of Norin 8. However, NR activity in M1004 was the same level as that in Norin 8. Seedlings of four selected lines took up nitrate to the same extent or a higher than Norin 8.

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Plants were regenerated from protoplasts of Ipomoea triloba L., one of the related species of sweet potato (I. batatas (L.) LAM.) at a high frequency. Protoplasts were isolated from in vitro-grown plants of I. triloba L. and then cultured in a modified liquid MURASHIGE and SKOOG (MS) medium containing 0.5mg/l 2, 4-dichlorophenoxyacetic acid (2, 4-D) and 1.0mg/l kinetin. First cell division occurred within 3-4 days. After 2 weeks protoplast plating efficiency was up to about 60%. After 12 weeks protoplast-derlved calli up to 2 mm in diameter were transferred onto solid MS medium supplemented with 0.2mg/l 2, 4-D for the proliferation. Three weeks after transference, they were further transferred onto MS medium supplemented with 0- 0.1mg/l 3-indoleacetic acid (IAA) and 1.0-5.0mg/l 6-benzylaminopurine (BAP) (regeneration medium) and after 2 weeks started to form adventitious roots. Subsequently, the calli were further cultured on MS medium without plant growth regulators and started to regenerate shoots 5 days after transference. When 2.0mg/l BAP was added to the regeneration medium, the regeneration frequency of protoplast-derived calli up to 36.7% was achieved. It was found that (0.2mg/l) 2, 4-D included in the proliferation medium played an important role in promoting shoot regeneration. After the regenerated shoots were transferred onto fresh MS medium without plant growth regulators, they developed into whole plants which were grown to maturity in pots with vermiculite.

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For identifying new sources of resistance to bacterial blight of rice, we inoculated rice cultivars from the International Rice Germplasm Center (IRGC) of International Rice Research Institute (IRRI) with races 1, 2, 3, and 4 of bacterial blight pathogen from Philippines. Based on the reaction patterns to the four races, rice cultivars were classified into eight groups. Four groups are based on single genes. (1) Java 14 group having resistance to four races with brownish margins around lesions. Cultivars of this group have Xa-3 for resistance. (2) TKM 6 group with resistance to race 1, moderate resistance to race 4 but susceptibility to races 2 and 3. Cultivars of this group have Xa-4. (3) DZ 192 group with resistance to races 1, 2 and 3 and moderate resistance to race 4. Cultivars of this group have xa-5. (4) CAS 209 group with resistance to race 2 only. Cultivars of this group have Xa-10. Four groups, each having two genes were recognized. These groups are: Mond Ba (Xa-4+Xa-10), DV85 (xa-5+Xa-7), Makhmal Mehi (xa-5+Xa-4), and BJ1 (xa-5+xa-13). Electrophoretic variation at isozyme loci was examined in a number of cultlvars belonging to different groups. These results suggest that the differentiation of BB resistance genes probably linked with the differentiation of cultivars into distinct ecotype.

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Cultivars of common rice (Oryya sativa ) have been classified by many researchers based upon different methodologies and approaches. Among the varietal groups defined by the reseachers, types A, B and C proposed by MATSUO (1952), and Indica, tropical and temperate Japonicas proposed by OKA (1953) have been frequently cited. MATSUO's Varietal groups (types A, B and C) are often considered to correspond to OKA's temperate Japonica, tropical Japonica and Indica, respectively. Here I report that such correspondence was not concluded.

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Many genetic studies have so far revealed a number of genes responsible for heading-time of rice. However, the knowledge about these respective genes has yet been of little use for actual breeding program. For saving this situation, it is necessary to detect and identify the genes controlling the heading-time of presently grown varieties, to clarify the relationships among known, detected and identified genes, and thus to systematize the information about heading-time genes. From these points of view, gene analysis of the heading time of Japanese rice varieties was undertaken with the aid of 7 tester lines named EG lines, which are different from one another in the genotype for three late-heading-time genes E₁. E₂ and E₃.

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Inheritance of callus formation in anther culture of rice (Oryza sativa L.) was studied by 6 x 6 diallel analysis by using Japanese lowland varieties (Aikoku, Hokuriku 100), Japanese upland varieties (Sekaiichi, Rikuto Norin Mochi 4, Akamai d) and Chinese lowland variety (I Kong Pao). There were significant varietal differences in the ability of callus formation, from 42.9% (Sekaiichi) to 0.0% (I Kong Pao). Japonica varieties of both lowland and upland showed higher callus formation ability than Indica varieties. The heritability for callus formation ability was quite high.

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Thirty doubled haploid lines of wheat derived from an F₁ hybrid carrying the gibberellininsensitive semi-dwarfing genes Rht1 and Rht2 were used to assess their effects on agronomic traits. The effect of these genes was additive for the reduction of plant height. Semidwarf lines carrying either Rht1 or Rht2 produced the same grain yield as tall lines did under artificial support to prevent lodging. Dwarf lines carrying both genes showed a remarkable decrease in grain yield. The genotype background in hybrid recombination modified both plant height and grain yield, but did not produce a variation that exceeded the effects of semi-dwarfing genes.

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Embryogenic and nonembryogenic calli of carrot were visually selected and cultured individually for 3 weeks on MURASHIC.E and SKOOG'S (MS) agar medium supplemented with 5 x 10^-6 M 2, 4-dichlorophenoxyacetic acid (2, 4-D). They were dried to a moisture level of about 3% for 6 hours and recultured on MS medium without 2, 4-D. All the dried embryogenic calli survived and formed many embryos or plantlets. The dried nonembryogenic calli could not survive except for very small parts which appeared to be embryogenic calli. These results showed the possibility of selection of embryogenic calli by the application of the drying method.

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Barley (Hordeum vulgare L.) haploids were obtained from two intergeneric crosses (barley × maize and barley x Italian ryegrass). In both crosses, 2, 4-D treatment after pollination was necessary to obtain the barley haploid embryos. Especially in barley × maize crosses, it was proved that application of a 75ppm 2, 4-D solution increased the efficiency of embryo differentiation (number of embryos obtained /number of florets pollinated) and haploid production (number of haploids obtained/number of florets pollinated). The efficiency of embryo differentiation and haploid production in barley × maize crosses ranged from 0.0%to 19.6% and from 0.0% to 6.9%, respectively, among the 14 barley cultivars examined. In the crosses of barley with Italian ryegrass, these values ranged from 0.0% to 16.7% and from 0.0% to 10.4%, respectively, among the 3 barley cultivars examined.

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The mode of inheritance of geotropic responses in wheat primary seminal roots was investigated in materials cultured on an agar medium. F₁ and F₂ plants frorn the cross between Norin 58, which shows large growth angles of inclination of the roots, and Chinese Spring, which shows small values, were examined. Means and standard deviations of growih angles of inclination of the roots for Norin 58, Chinese Spring and the F₁ plants were 68±21°, 16±14°and 15±21°, respectively. The corresponding values of the F₂ plants ranged from O' to 90°. The observed segregation of the F₂ plants with small (0∼50°) and large (60∼90°) values fitted to the ratio of 3 : 1. Therefore, the limited geotropic response associated with a small growth angle of inclination of the root was considered to be controlled by a single dominant gene.

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