Glabrousness of the rice cultivar Sumitakara produced through somaclonal variation by anther culture was studied genetically and morphologically. Scanning electron microscopic observation revealed that all of twelve pubescent rices including the mother cultivar Koganebare had one type of hair and three kinds of bristles on their leaf surface. In contrast, Sumitakara as well as the other glabrous cultivars bred by crossbreeding had one type of hair and no bristles. The results imply that the glabrousness of Sumitakara is due to inhibition of bristle formation and that hair formation is controlled differently from bristle formation. It was interpreted from the genetic analysis of the number of bristles on leaves of both F₁ and F₂ populations of Sumitakara crossed with glabrous or pubescent cultivars that the glabrousness of Sumitakara could be controlled by one recessive gene which was located at the same locus as that in a glabrous cultivar Akenohoshi bred by crossbreeding. Reversion to pubescence, on the other hand, suggested trichome formation in rice was regulated by several genes.

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Allozyme variation in 11 natural populations of hinoki, Chamaecyparis obtusa (SIEB. et ZUCC.) ENDL. was studied using 10 Ioci, and compared with that in 12 groups of hinoki plus-trees selected from artificial stands in the national project for plus-tree selection breeding. In the natural populations, it was evident that most of the genetic variation was retained within populations, and population differentiation was low, as observed in many other gymnosperms. However, there were genetic clines in allele frequencies at 4 Ioci, G6p, Pod, Got-1 and Pgm along the geographic locations of the populations. The populations were mostly separated according to the locations using two clustering methods based on genetic distances among populations. Comparison of allozyme variation between the natural populations and plus-tree groups revealed that generally the variation in the natural populations was preserved even in the plus-tree groups. However, genetic differences were observed between the natural populations and the plus-tree groups in the presence or absence of rare alleles, the mean frequencies of alleles, and the distribution of allele frequencies across the natural populations or the plus-tree groups.

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Interspecific hybrids between Alstroemeria ligtu L. hybrid and A. pelegrina L. var. rosea were produced by using ovule culture. In this cross combination, viable seeds could not be obtained in the reciprocal crossings. Histological observation revealed that the hybrid embryos aborted around 28 days after pollination in the crossing of A. Iigtu hybrid × A. pelegrina var. rosea and around 35 days after pollination in the reverse crossing without appreciable development of endosperm. When ovules with placenta were transferred to 2 g/l Gelrite-solidified MS medium containing 3 % (w/v) sucrose before the embryo degeneration, plantlets were formed in the reciprocal cross combinations. However mature plants were obtained only in a cross of A. Iigtu hybrid × A. pelegrina var. rosea. The hybrid plants had intermediate characteristics between the parents, and complete haploid genomes of the both parents. Hybridity of the plants was also confirmed by DNA analysis.

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Parental cultivars (Oryza sativa L. Japanese lowland cultivars Sasanishiki and Norin 1), F₂ plants, and F₃ Iines were grown under visible light with or without supplemental UV-B radiation in a phytotron, to determine whether the accumulation of UV-absorbing compounds plays a role in the difference in UV-B resistance between these rice cultivars. The level of UV-absorbance per unit leaf area increased with the UV-B treatuent in all the leaves of these two rice cultivars, but was higher in Sasanishiki than in Norin 1 irrespective of UV-B treatment. An analysis by thin-layer chromatography and the UV-absorption spectra of the extracts did not show any qualitative difference in UV-absorbing compounds in leaf tissues between these two cultivars. There was a significant positive correlation between the level of UV-absorbance per unit leaf area and the fresh weight of aerial parts in the F₂ plants exposed to UV-B radiation. Furthermore, the level of UV-absorbance per unit leaf area tended to be higher in the F₃ Iines resistant to UV-B radiation than in those sensitive to such radiation regardless of whether these F₃ lines were exposed to supplemental UV-B radiation. These results suggest that the differences in UV-B resistance between Sasanishiki and Norin 1 are associated with genetic differences in the level of accumulation of UV-B absorbing compounds in leaf tissues. Based on these results we suggest that the accumulation of UV-B absorbing compounds is an important factor contributing to UV-B resistance in rice cultivars. Since the accumulation of UV-absorbing compounds in leaves appears to minimize the latent negative impact of UV-B radiation on rice production, it may be a useful character to select in ordinary breeding.

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The analysis of five isozyme loci ; Pgi-1. Pgi-2. Amp-1, Amp-2, and Amp-3 identified Isozyme types (Isotypes) for the cultivars resistant to bacterial blight (BB) in Myanmar. The results indicated that all the cultivars of Cas 209 group (Xa-10), TKM 6 group (Xa-4), and Mond Ba group (Xa-4 + Xa-10) belonged to Isotype I, whereas the cultivars of Java 14 group (Xa-3) were in Isotype V. The cultivars of DZ 192 group (Xa-5) were classified either into IsotypeI or intermediates. These intermediates were considered as an intermediate of IsotypeI and Isotype II. The morphological observations revealed that IsotypeI of DZ 192 group was different from IsotypeI of Cas 209 group and of TKM 6 group. The algorithm survey of Cas 209 group and TKM 6 group found that the most frequent algorithms used in the two groups were different, and that Amp-1⁴ was specifically predominant in Cas 209 group, whilst TKM 6 group was consisted of Amp-1¹ only. The distribution of Amp-1⁴ had remarkable concordance with the distribution of Cas 209 group in Asia. The cultivars of TKM 6 group tended to involve wider range of phenotypes and the distribution in Asia is also wide. These results indicated that the origin of Cas 209 group and TKM 6 group might be different.

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Two cultivated tomatoes as seed parents and 9 Iines of `peruvianum-complex' (2 Iines of L. peruvianum var. humifusum, 5 Iines of L. peruvianum, and 2 Iines of L. chilense ) as pollen parents were used for obtaining F<sub>l</sub> hybrid and B<sub>I</sub>F<sub>I</sub> backcross generation by using the ovule selection method. In respect to the efficiency of obtaining F<sub>1</sub> and B<sub>1</sub>F<sub>1</sub> (which is evaluated by the number of germinated ovules per fruit)(GOF), three correlation coefficients were calculated, between the two cultivated tomatoes, between 1994 and 1995 for B<sub>1</sub>F<sub>1</sub> and between F<sub>1</sub> and B<sub>1</sub>F<sub>1</sub>. Between the two cultivated tomatoes, a significant, combined correlation coefficient was obtained from the 3 correlation coefficients of F<sub>1</sub> in 1992, B<sub>1</sub>F<sub>1</sub> in 1994 and B<sub>1</sub>F<sub>1</sub> in 1995 (r = 0.750 <sup>**</sup>, d.f. = 11). Between the two years, a significant, high, and combined correlation coefficient was obtained (r = 0.907<sup>*</sup>, d.f. = 3). The correlation coefficients between F<sub>1</sub> and B<sub>1</sub>F<sub>1</sub> and a combined correlation coefficient were not significant in either of the two cultivated tomatoes. One of the 9 Iines used in the present study showed a different and unusual GOF for F<sub>1</sub> and B<sub>1</sub>F<sub>1</sub>. After the one line is excluded, the correlation coefficient become significant (r = 0.754<sup>*</sup>, d.f. = 5). This analysis of the correlation coefficient indicates that the differences between the lines of `peruvianum-complex' as regards the cross-incompatibility with a cultivated tomato exist and that the differences are found similarly in both F₁ and B₁F₁. The two lines of L. peruvianum var. humifusum belong to the highest cross-incompatibility group, most of the lines of L. peruvianum belong to the intermediate group, and the two lines of L. chilense belong to the least cross-incompatibility group. The alternative relationship between F₁ and B₁F₁ is evaluated by linear regression : Y (B₁F₁) = 0.l082X (F₁) + 0.3364 for : `Kyoryoku Ogata Toko', Y = 0.1054 X + 0.0366 for‘Early Pink'. From the result, it is shown that B₁F₁ is not bigger than F₁ in terms of GOF.

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Soybean (Glycine max (L.) Merr.) cultivars occur in two types, the vegetable-type (edamame) and the grain-type cultivars. This study was carried out to examine the characteristics of accumulation of water-soluble nitrogen and amino acids in immature and mature seeds from these two types of soybean cultivars. Ten vegetable-type and thirteen graintype cultivars were grown in an upland field of Yamagata University. The immature seeds were sampled 30 to 40 days after flowering. Concentrations of the water-soluble nitrogen measured in 1991 were highly correlated with amino acid concentrations measured in 1992. The immature seeds of the vegetable-type cultivars contained higher concentrations of seven free amino acids (asparagine, alanine, glutamic acid, arginine, serine, histidine and valine) than those of the grain-type cultivars. Based on concentrations of these amino acids in immature seeds, we correctly discriminated the vegetable-type and grain-type cultivars, indicating that differences in amino acid concentrations in the immature seeds were sufficient to distinguish the two types of soybean cultivars. Furthermore, the concentration of water-soluble nitrogen may be a simple measure that represents concentrations of free amino acids, and can thus be used as one of the selection indices in breeding programs of the vegetable-type cultivars.

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Sixteen strains of foxtail millet, Setaria italica (L.) P. Beauv., originally collected from Pakistan were crossed with three strains which had previously been used as testers for classifying six landrace groups based on hybrid pollen sterility. Wide variation was observed in pollen fertility of the F₁ hybrids, ranging from 14.2% to 94.7%, while pollen fertility of all the selfed Pakistani strains and testers was normal. Pakistani strains were classified into type C (8 strains), type BC (2) and type X (6) on the basis pollen fertility of more than 75% is normal fertility. No A, B or AC type strains were detected. Type C was found in land-races collected from Punjab Province, the southern part of the North-West Frontier Province (N. W. F. P.) and Baltistan. Type X was distributed in the northern part of N. W. F. P. and an adjacent area of the western part of Gilgit Agency, in the northeastern part of Gilgit Agency and in Baltistan. Different landrace groups were suggested among the strains of type X by the variation in hybrid sterility observed with each tester. This observation was strongly supported by an almost sterile hybrid between type X strains from N. W. F. P. and the northeastern part of Gilgit Agency. Type BC was found in Gilgit Agency and Baluchistan. Landrace groups classified by hybrid pollen fertility did not show any clear relationship with morphological groups which had a different geographical distribution. The present results imply that S. italica, with various phylogenetic backgrounds, might have been introduced into this region several times, and subsequently evolved into three distinct morphological groups.

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In the mitochondria of rice (Oryza sativa L.), four kinds of small circular plasmid-like DNAs, designated B1, B2, B3 and B4, have been characterized. However, their function is unknown. To investigate their function, we analyzed the transcription of B1, B2, B3 and B4 by Northern blot hybridization and RNase protection assay. We found that B1, B2, B3 and B4 are transcribed in one direction in both seedlings and suspension-cultured cells of rice. From the results of RT-PCR and the Northern blot hybridization, it is suggested that B1, B2, B3 and B4, Iike other mitochondrial genes, are transcribed without termination and are processed to specific sizes of transcripts. These transcripts contain ORFs, but no homologous sequences were found in the databases except for an ORF in B3. Thus, it is still unclear whether these transcripts code functional proteins. Our results may complement the hypothesis concerning the transfer of plasmid-like DNA sequence via RNAs from mitochondria to nuclei.

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Brassica oxyrrhina Coss. (OxOx genone, 2n=18), a wild Brassica species was repeatedly backcrossed with radish (Raphanus sativus. L., cv. Miyashige, RR genome, 2n= 18) (Fig. 1, Table 1, 2, 3 and 4) . In the B₂ generations, plants with 2n=18 chromosomes were obtained (Fig. 2). In the process of cytoplasm substitution, restoration of pollen fertility was not observed (Fig. 3). Thus, it was assumes that the depression of pollen fertility was due to the effect of B. oxyrrhina cytoplasm (Figs. 3, 5 and 6). Though the seed fertility of plants increased when their chromosome numbers were close to 2n=18, fertility was not restored up to the normal level (Fig. 4). No seeds were obtained from the plants in which pollen fertility was below 50 % and It was considered that cytoplasmic male sterility had been induced. Cytoplasm-substituted radish plants were backcrossed two times with nine commercial cultivars. Thereafter, nine plants with B. oxyrrhina cytoplasm were reciprocally crossed with each cultivar (Table 5). Two kinds of F₁ plants (B. oxyrrhina-cytoplasmic F₁ and R. sativus.-cytoplasmic F₁) were used as materials for the comparative studies. In the F_l plants with B. oxyrrhina cytoplasm, the chlorophyll content was never reduced (Table 6). The values of root length, root diameter, root weight and leaf weight in the F₁ plants of‘Akamaru hatsuka', ‘Shogoin', ‘Shijunichi' and ‘Miyashige' with B. oxyrrhina cytoplasm were lower than those of the F₁ plants with R. sativus. cytoplasm. In case of F₁ plants of ‘Raddike ostergruss' and ‘Nerima', there were no differences between B. oxyrrhina and R. sativus. cytoplasms (Table 6, Fig. 7). It is considered that these plants harboured a gene (or genes) compatible with the B. oxyrrhina cytoplasm. Therefore, it is suffered that the inhibition caused by the interaction between nucleus and cytoplasm may be released by hybridization.

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Genomic in situ hybridization was carried out for mitotic cells of the interspecific hybrids of Nicotiana rustica L. (2n = 48)× N. tabacum L. (2n = 48) and N. gossei Domin (2n = 36)× N. tabacum L. Without blocking DNA of N. tabacum, clear hybridization signals from the biotinylated total genomic DNA of N. rustica or N. gossei, were obtained for the set of chromosomes, indicating that each parent could be discriminated. In the hybrid of N. rustica × N. tabacum, twenty-four chromosomes among forty-eight chromosomes were confirmed to be derived from N. rustica. Furthermore, two chromosomes exhibited regions with weak hybridization signals, suggesting that interspecific translocations might have occurred between N. rustica and N. tabacum chromosomes. On the other hand, in the hybrid of N. gossei× N. tabacum, eighteen chromosomes showing a hybridization signal over the entire length, were discriminated from the forty-two hybrid chromosomes. No region with weak signal was detected in any of them.

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