Glutamate oxaloacetate aminotransferase (GOT) and peroxidase (POD) isozymes of yamamomo (Myrica rubra SIEB. et ZUCC.) cultivars were analyzed by native polyacrylamide gel electrophoresis (PAGE). A Leaf bud was sampled for enzyme extraction due to the strongest actlvity of the enzyme at this stage of leaf development. Since the elect.rophoretic patterns of two zones of GOT isozymes and one of POD isozymes varied among the cultivars, it was considered that the combination of the zones of these isozymes would enable to identify cultlvars with different names as synonyms or, on the contrary, cultivars with similar names as different ones. Two cultivars, considered to be of Chinese origin, could apparently be distinguished from the other Japanese cultivars by such isozyme analysis.

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In order to identify the bacterlal blight resistance gene of rice cultivar IR8, one of the rice baceterial blight differentials, a research was carried out under a collaboration between Ministry of Agriculture, Forestry and Fisheries (MAFF), Japan and International Rice Research Institute (IRRI), Philippines. Inoculation test using Japanese and Indonesian races of bacterial blight pathogen, was first carried out with cultivars which are known to show the reaction pattern similar to that of IR8. The results indicated that cultivars of IR8 reaction pattern showed resistance to Japanese races IB, II, IIIA and V, and Indonesian races IV and V but susceptibility to Japanese races IA, IIIB and IV. It was found that Japanese race IV differs pathogenetically from Indonesian race IV. Moreover, there was no difference between the reaction pattern of Elwee and Heen Dikwee which were considered to belong to different reaction groups by YAMADA et al. (1979a). The results of gene identificatlon by F₂ analysis showed that IR8, Elwee and RP9-3 have the same gene for resistance to Japanese races IB and IIIA. The allelic test between the resistance gene of IR8, Elwee, and RP9-3, and the resistance gene(s) of Peta and IR944-102-3-2 showed that Peta and IR944-102-3-2 also have the same gene with IR8 and have another dominant gene for resistance to Japanese races. This study showed that IR8, Elwee, RP9-3, Peta, and IR944-102-3-2 have the gene Xa-11 for reslstance originally identified by OGAWA and YAMAMOTO (1986).

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In this study the material of 'peruvianum-complex' was extended to L, peruvianum to confirm the efficiency of ovule culture ile vitro reported previously (IMANISHI et al., 1985; IMANISHI, 1988) and cross-compatibility between the cultivated tomato and the 'peruvianumcomplex' was assessed by the in vitro ovule culture. Four cultivars as the female parents and L. chilense (2 lines) and L. peruvianum (1 line) as the male parents were used. No normal seeds were found in the ovules taken from the ripe crossed fruits. Visual observation, however, suggested that a few ovules had the potential for germination, based on the characteristics described by IMANISHI (1988). In the cross between Early Pink and L. chilense (PI 128652), 30 ovules out of the large number of ovules were selected by the visual observation to observe embryos contained. Dissection under a microscope revealed 23 incomplete embryos in the 30 ovules . Ovules with this potential for germination were selected visually in the crosses between Early Pink or Kyoryoku Toko and three male parents. They had high germination rates when plated on MS agar medium (MURASHIGE and SI(ooG, 1962) without phytohormone. This result indicates that in vitro ovule culture based on the visual selection can be applied not only to L, chilense but also to L. peruvianum.

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Individual seeds of 212 common bean cultivars were analyzed by Ouchterlony immunodiffusion method using the antiserum raised against common bean α-amylase inhibitor (CBAI). Two cultivars, Ofuku-5 and Ofuku-8, gave no reaction with the anti-CBAI serum and no inhibitory activity against porcine pancreatic α-amylase. Furthermore, these CBAI-lacking cultivars contained no lectin.'Analysis of F₂ seeds from the cross between Ofuku-5 and Taishou-kintoki (CBAI-containing) indicated that the absence of CBAI was recessive to the presence of CBAI and tightly linked to the absence of lectin. In a previous report, we showed that CBAI strongly inhibited the larval growth of Callosobruchus chinensis. Thus, effects of the absence of CBAI on the larval growth of C. chinensis were examined using artificial beans containing seed components of the two CBAI-lacking cultivars and two CABIcontaining cultivars (Taishou-kintoki and Ofuku-1). The flour of the CBAI-lacking cultivars showed weak inhibitory activity on the larval growth compared with that of the CBAI-containing cultivars, although the larvae could not grow in the intact seeds of the CBAI-lacklng cultivars. The role of lectin, which was also absent In the seeds of Ofuku-5 and Ofuku-8, has been implicated with resistance to insects, especially bean weevils. CBAI and the lectin in the seeds of the CBAI-containing cultivars were separated well by extraction with 20mM sodium phosphate buffer solution and subsequent ammonium sulfate fractionation. The feeding tests using the protein fractions separated from the CBAI-lacking cultivars and the CBAI-containing cultivars demonstrated that the absence of CBAI is considerably responsible for the lowering of the growth inhibitory activity of the flour of CBAI-lacking cultivars.

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The eifects of a few dwarfing genes on the cool temperature tolerance at the booting stage were investigated. The genes were d-47(t) (dee-geo-woo-gen dwarf), sd-1 allelic to d-47(t), d-18^k (kotaketamanishiki dwarf), and d-35(t) (tanginbozu dwarf). The following lines were used: Shiokari (one recurrent parent), and Its isogenlc lines of d-47(t), d-18k and d-35(t); Taichung 65 (the other recurrent parent) and its isogenic line of d-47(t); Calrose 76 containing sd-1 and Calrose; and Kotaketamanlshiki, the gene source of d-18k and Tamanishiki. Cool treatments were conducted for 3 days at 12'C, 4 days at 12'C, 4 days at 13'C or 6 days at 13'C. In the 12'C-3-day treatment in 1986, Shiokari was found to have the 10west spikelet fertility (69.9%) in the treatment untll 10 days before heading, while the d-47 isogenic line showed distinctively low fertilities (45.7-51.2%) during the five days from 13 to 9 days before heading. The d-35 isogenic line showed lower spikelet fertilities than the d-47 isogenic line in 1985. The average spikelet fertility of the 5 consecutive days, on which the average value is the lowest, was designated as "L5". In the 13'C-6-day treatment in 1989, the L₅ of the d-47 isogenic line of Taichung 65 was 11.0% Iower than that of Taichung 65, The L₅'s of the d-18^k isogenic line and Kotaketamanishiki were 8.5% and 6.6%, respectively, higher than those of their parental cultivars, Shiokari and Tamanishiki. The L5 of Calrose 76 was 12.0% Iower than that of Calrose. The decreases in spikelet fertility were almost accompanied by decreases in the number of pollen grains per anther. It Is inferred from these results that the effects of the dwarfing genes on the cool temperature tolerance at the booting stage are in the order of d-18^kd⁺(tall)d-47(t)d-35(t). d-47(t) seems to have a disadvantage in this character.

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The effects of nltrogen fertilizer supply on the genetic variability of 12 quantitative characters in rice were investigated, uslng ten varieties of Indica and Japonica each. Four nitrogen levels were applied In a split-plot design experiment. In the analysis of varlance, 8(Indica) or 10 (Japonica) out of the 12 characters examined showed significant nitrogen effect. In most of the significant characters, F values for nitrogen effect in the analysis of variance were larger in Indica than in Japonica, but F for genotype × nitrogen interaction gave no such differences. Stability of a broad sense heritability at different nitrogen levels varied with the characters. Number of days from sowing to heading gave high and very stable heritability, while effective tiller percentage and filled spikelet percentage showed moderately or highly variable heritability. Most of the characters showed higher heritability in Indica than in Japonica. As judged by magnitude of coefficient of variation in the heritability and in the varlance component for genotype, Indica varieties were stable over different nitrogen levels relative to Japonica varieties. It was suggested that breeding materials should be subjected to selection at a proper nitrogen ievel which maximize heritability of the character concerned, unless the order of lines as regards the magnitude of characters differs with nitrogen levels.

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The locations of nine isozyme genes on conventional linkage maps were studied in rice (Oryza sativa L.). Two isozyme genes on chromosome 12 showed a linkage with the gene for bonsaito dwarf (d-33) which is a marker on the same chromosome. Based on the data, the gene order was estimatecl as Acp-1-Pox-2-d-33. Pgd-1 was found to be linked to la, v-4 and Adh-1 on chromosome 11. It was possible to confirm that the order of these genes was la, v-4-Pgd-1-Adh-1 based on the linkage relations. From the co-segregation of Pgd-2 and other isozyme genes, linkage relations with Est-2 and Pgi-2 were detected on chromosome 6. Newly acquired gene (Gdh-1) was linked to Pgi-1. The genes were assigned to chrorno-some 3, because Pgi-1 showed linkage with two morphological markers, chl-1 and v-1 which are located on chromosome 3. Based on the linkage data, it was confirmed that the order of these genes was chl-1-Pgi-1-v-1. In total, new linkage relations of nine isozyme genes were determined. These and published data were used in linkage maps constructed with 11 isozyme *crenes and six morphological markers on conventional linkage maps. The genes were distrlbuted to four out of twelve chromosomes in rice.

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The factors affecting somatic embryogenesis in suspension culture of melon seed and the process involved were described. The culture period in the initial culture medium supplemented wlth 1mg/l 2, 4-D, 1mg/l NAA, 0.1mg/l BA and 30g/l sucrose, influenced the structural characteristic of the somatic embryo. When the suspension was cultured for 7 days in the initial medium, the somatic embryos which developed normal morphogenesis predominated. A larger number of normal somatic embryos were obtained when the 7-day-old cultures were washed with MS medium containing 0.5% activated charcoal. Somatic embryogenesis began in the filamentous embryo stage and proceeded from globular to torpedo stage.

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To increase the genetic resources for resistance to bacterial blight (BB) caused by Xanthomonas campestris pv, oryzae in rice, we initiated a study to induce mutants with resistance to BB by chemical mutagen. Fertilized eggs of a susceptible cultivar, IR24 to Philippine BB races were treated with N-methyl-N-nitrosourea (MNU) at the singie-cell stage of embryogenesis. The panicles of F₁ plants were bagged before flowering to avoid any outcrossing. M₂ lines, derived from each M₁ plant, were inoculated with a Philippine BB race 5 (isolate PXO 112) at the seedling stage. As a result, out of 2, 739 M₂ lines tested, two resistant mutant lines were found and they were designated XM5 and XM6. M₃ progenies derived from M₂ plants in both mutant lines were tested for segregation for resistance. The results suggested that resistance of these mutant lines was induced by the MNU treatment. The mutation frequency of BB resistance was 7.30 × 10^-4. (no. of resistant mutant lines/no. of tested M₂ lines). Both of the mutant lines showed resistant to all six known Philippine BB races. We crossed these two resistant mutant lines with IR24 to clarify their inheritance of resistance. The reaction of F₁ hybrids and F₂ populations to BB races suggested that both mutant lines have single recessive genes for BB resistance.

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Rice cultivars from Myanmar were evaluated for resistance to four Philippine races of bacterial blight pathogen (Xanthomonas campestris pv. oryzae) with clipping inoculation method (KAUFFMAN et al. 1973). Out of 1473 cultivars screened at seedling stage. 337 cultivars were initially categorized into five groups by their differential reactions to races 1, 2, 3, and 4 e.g. SRSS, RSSM, RRSM, RRRM (or RRRR) and MMMM. The MMMM reaction at seedling stage was further classified either into RRRR with browning reaction around lesions or moderately resistant cultivars (non-classified) on the basis of repeated tests at adult stage. As discussed by OGAWA et al. (1991), the RRRR reaction with the browning around the lesions is similar to that of Java 14 group. The cultivars of this group were considered to have Xa-3 for resistance. The reactlon SRSS is similar to that of CAS 209 (Xa-10) group. Likewise, the reaction patterns of RSSM, RRSM, and RRRM (without browning) resembled the reaction patterns of TKM 6 (Xa-4), Mond Ba (both Xa-10 and Xa-4), and DZ 192 (xa-5) groups, respectively. Out of 337 cultivars screened at adult stage, 218 were susceptible. Of the 119 resistant cultivars, 44 were placed in CAS 209 group, 33 in TKM 6, 4 in Mond Ba group, 9 in DZ 192 group, 3 in Java 14 group, and 26 as non-classified cultivars. The raction of the cultivars of each group was compared with that of each of the near-isogenic lines having a specific gene for the cultivar groups. Homogeneity of each group was confirmed through variance analysis over three seasons. Thus, the cultivars of CAS 209 and TKM 6 groups were predominant with a small number of cultivars belonging to Java 14 and DZ 192 groups.

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The genetic control of the photosynthetic capacity of a single leaf was studied in rice. The photosynthetic capaclty was estimated as the amount of oxygen evolved that was measured by oxygen polarography using a multi-channel apparatus. The amount of oxygen evolved by the F₁ plants and the F₂ populations of the two reciprocal crosses; Zaiyeqin 8 (high capacity) × Shinshukaneko (low capacity) and Jukkoku (high) × Naxi (low), were measured. The frequency distribution of the amount of oxygen evolved which was measured at a fixed period of measurement in the F₂ populations showed a normal dlstribution.

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Computer simulation of diallel crosses was carried out to investigate the influences of environmental variation involved in the values of a diallel table on the (V_r, W_r) graph and on the genetical components of variation. The influences on V_r and W_r were not uniform, but varied with parents, being greater for parents with a larger number of recessive alleles. The variation of V_r and W_r exhibited a positlve correlation, which was closer for more recesive parents. Heterogeneity and correlation of the variation of W_r and V_r invalidated the t-test on the regression of W_r on V_r, analysls of variance for the heterogeneity of W_r, V_r among arrays, and estimation of the standard errors of genetical components of variation by the least squares method. The standard error of the genetical components D, F, H₁, H₂, and h² estimated by the least squares method was slightly or much smaller as compared with that obtained by simulation. Distributions for the estimate of the average degree of dominance, the number of genes, and the proportion of dominant alleles in all the parents, and for the regression of W_r on V_r were widely dispersed, and some of the values of the parameters deviated considerably, even at a fairly high heritability level (h² = 0.7). It was concluded that diallel analysis loses its utility unless the heritability value is 0.8 or higher.

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Hybrid cell lines were produced by the intergeneric protoplast fusion between Luffa cylindrica ROEM. (L. cylindrica) and Gynostemma pentaphyllum MAKlNO (G, pentaphyllum). Protoplasts derived from the cotyledons of L. cylindrica and protoplasts derived from the cultured cells of G. pentaphyllum were fused according to the method of MENCZEL and WOLFE. Four fusion products were confirmed as hybrid cells based on isozyme analysis

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The nature-reserve population of a rare species, Primula sieboldii in the Tajimagahara flood plain of the Arakawa River in Saitama Prefecture has been designated as precious natural product. However, recently the population has decreased tremendously and faces extinction as a result of biological and abiological changes in the environment due to rapid urbanization, etc. In terms of conservation of this rare species, WASHITANI et al. (in press) assessed intrapopulational variations of several characteristics related to fertility and found that there were wide inter-clonal variations of fertility, phenology, etc. and that insect visitation was rarely observed in this area. To build up a scheme for conservation of the population, we tried to clarify the genetic variation within the population.

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A Mutation causing the abnormal development of grains was induced in rlce (Oryza sativa L.) by means of the tetraploid-irradiation technique. The grain was about half of the size of a normal brown rice and consisted entirely of the embryonic tissue. Microscopic observations revealed that the endosperm cells stopped dividing at early developmental stage, while the embryo continued growing into a large cellular clump in which a plumule, a radicle and a scutellum differentiated. We termed these grains endospermless grains. On the basis of the segregation ratios of endospermless grains, it is concluded that a recessive allele on a single locus or a deletion of small chromosomal segment is resposible for the abnormal development of grains.

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Somatic embryos of melon (Cucumis melo L.) were cryopreserved in liquid nitrogen (LN₂) after controlled desiccation. Desiccation of embryos was carried out slowly under controlled relative humidity (RH) of 50-65 % after preculture with 10mg/l abscisic acid (ABA). Desiccated embryos were immersed directly into LN₂. Of the total number of embryos 65 % survived storage in LN₂ when desiccated at a RH of 60 %. Viability was affected mainly by the size of the embryos. The water content of the desiccated embryos was 11.8% at RH 60%, which was considered to be reasonably low to avoid freezing injury of the cells. This study demonstrates that the desiccation method enabled the cryopreservation of melon somatic embryos without the use of expensive facilities.

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Thirty-nine genotypes of maize (Zea mays L.) and one genotype of teosinte (Zea mays ssp. mexicana ) were investigated for the production of haploid plants in common wheat (Triticum aestivum L. var. Nishikazekomugi). The method to product them was followed: the detached wheat spikes pollinated by teosinte or maize genotypes were cultured in a solution of 100mg/l 2, 4-dichlorophenoxyacetic acid, 10ml/l ethanol, 0.8ml/l sulfurous acid and 40g/l sucrose for 16 days, and subsequently excised embryos were cultured on B₅ medium. Wheat × teosinte cross was the highest in frequency of embryo obtained (38.5%) and in haploid frequency per pollinated florets (31.5%). It is suggested that teosinte can be used effectively in haploid breeding programs of wheat employing intergeneric crosses.

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In order to analyze the cause of the highly spikelet sterility observed in the F₁ hybrids between Silewah and Hayakogane, reciprocal crosses between Hayakogane and Silewah were conducted. Since F₁ hybrids in the reciprocal crosses showed slmilarly low spikelet fertility, the spikelet sterility in the F₁ hybrids was not caused by cytoplasmic male sterility. In addition, the F₁ hybrids displayed normal pollen fertility and crossed seed fertility in reciprocal crosses between F₁ hybrids, Silewah/Hayakogane and Hayakogane was normal. These results indicated that pollen and ovule of the F₁ hybrid were normal. The F₁ hybrids between Silewah and Hayakogane showed a large number of indehiscent anthers. Accordingly, it was deduced that the highly spikelet sterility in the F₁ hybrlds between Silewah and Hayakogane was mainly caused by indehiscent anthers. When spikelet fertility in the F₁ hybrids between pedigrees of Hayakogane and Silewah was examined, the F₁ hybrid between Norin 15 and Silewah showed the same extremely low spikelet fertility as that of the F₁ hybrid between Silewah and Hayakogane. Furthermore, the F₁ hybrids between either Kyowa or Hokuto and Silewah were partially fertile. The slightly decreased fertility was also observed in the F₁ hybrids between either Hashiribozu or Matsumotomochi. These F₁ hybrids had normal pollen fertility and a number of indehiscent anthers. The F₁ hybrids of the remaining pedigrees of Hayakogane crossed with Silewah showed a normal spikelet fertility in F₁ hybrids crossed with Silewah. These results suggest that varietal differentiation for spikelet sterllity in the F₁ hybrids including Silewah may occur in Japonica rice varieties.

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Total DNA was extracted from leaves of grapevines, 8 cultrvars of Vitis vinifera, Concord (V. labrusca) and a rootstock variety, F-3309. All the tested DNA showed different Southern analysis patterns using L-phenylalanine ammonia-lyase (PAL) cDNA of carrot (Daucus carota) as a probe. A dendrogram based on the RFLPs of PAL cDNA relatively agreed well with morphological taxonomy.

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Ninety six tetraplold spring wheat genotypes and six hexaploid wheat cultivars were allowed to germinate in four growth chambers set at temperature regimes of 5°C, 10°C, 15°C, and 20°C. Temperature had a strong effect on seedling emergence time of all genotypes. This effect was much more dramatic at the lower than at the higher temperature values. Optimum temperature conditions (15°C and 20°C) were associated with smaller genetic variances for seedling emergence time. The 15°C and 20°C did not statistically differ in their effccts on emergence time. The 5°C and 10°C treatments can be successfully used to screen genotypes for their cold tolerance because of much larger genetic variances. Genotypes were classified into three categories according to their cold tolerance: tolerant, intermediate, and susceptible. Hexaploid genotypes were the most cold tolerant in this wheat population. The most cold tolerant tetraploid genotypes are 1460, Adamello, Creso, Echiopia Komugi 72-201, Kunduru 1149, Kyperounda, Latino, Mindum, and Norba. The emergence time of these 9 tetraploid genotypes was cornparable to that of the hexaploid genotypes. Under low temperature conditons some spring wheat genotypes performed simllarly as the winter types suggesting that cold torelance during seedling emergence is independent of varnalization requirement. There was no genotype x temperature interactionindicating that selection for cold tolerance is effective. The 10°C can be successfully used to screen genotypes for their cold tolerance durlng the emergence growth phase.

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