There are two morphogenic pathvways in plant regeneration. These are adventitious shoot and root formation (organogenesis) and somatic embryo formation (embryogenesis). To establish a rice (Oryza sativa L.) culture system, in which highly-frequency of either organogenesis or embryogenesis were achieved, effective regeneration media were investigated. We tested N6 medium containing 20 g·l^-1 sucrose, 35 or 50 g·l^-1 sorbitol, 3 g·l^-1 casein hydrolysate, lO mM L-proline, 10 g'l^-1 agarose and different levels of abscisic acid (ABA), auxin, and cytokinin for regeneration. In our culture system, the type of cytokinin was the key to control the morphogenic pathways. One of the most active urea cytokinins, N-(2- chloro- 4- pyridyl)-N' -phenylurea (4PUCl), tended to induce adventitious shoots. A purine cytokinin, kinetin, in low concentration tended to induce somatic embrvos.

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Rice seedlings were exposed to cold (5°C) at a relative humidity of 100 % for 24 h and a subtracted CDNA Iibrary was constructed. Six clones isolated by differential screening of the subtracted cDNs library were designated as RC (responsive to cold) clones. Increase of RNA Ievel detected with these cDNA probes was observed within 3 h under cold treatment. Thereafter the RNA Ievel either remained high or decreased during the initial two days of cold treatment. Reincubation of plants at 28 °C following the 5 °Ctreatuent caused a rapid decrease of RNA Ievels detected with all the clones. RNAS detected with four of the RC clones (RC42, RCI04, RC114, RC235) were also accumulated when seedlings were subjected to drought, abscisic acid (ABA) and NaCl treatlnents. However, accumulation of RNAs detected with two of the RC clones (RC167 and RC179) under these stress treatments was not observed, suggesting the existence of a specific pathway that is generated only by cold treatment, but not by other stresses. Examination of chilling injury and cold-induced accumulation of these RNAs in 22 rice varieties using four cDNA probes suggests that the accumulation of RC167 and RC235 mRNAs was associated with chilling sensitivity.

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Chromosome association and fertility of the hybrids of C. persicum (2n=2x=48)xC. hederifolium (2n=34) and the amphidiploids were compared with their parental species. The mean chromosome association per PMC at metaphase I in meiosis was 0.13 I + 23.93 Iin C. persicum and 0.15 I +16.92 II in C. hederifolium. These parental species formed normal cells at telophase I and the tetrad stage, and produced viable pollen grains and seeds. On the other hand, the hybrids (2n=41) showed partial chromosome association with a mean of 35.39 I + 2.81 II . They formed abnormal cells at telophase I and the tetrad stage, which resulted in sterile pollen. The hybrids failed to set a seed by cross-pollination with fertile C. persicum pollen grains, suggesting female sterility. In the amphidiploids (2n=82), bivalents were formed at high frequency and the mean chromosome association was 0.51 1 +40.75II. Meiosis proceeded normally and fertile pollen grains were produced. These amphidiploids yielded viable seeds by self- pollination. These observations suggest that C. persicum and C. hederifolium are distantly related within the genus Cycl amen.

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Relationship between the ratio of regenerable plants (regeneration frequency) and productivity of somatic embryos was studied for three different genetic sources of alfalfa (Medicago sativa L.), including (i) four commercial cultivars and three breeding populations, (ii) five selfed and (iii) three crossed progenies of regenerants. Number of somatic embryos, stability of embryo formation and days to embryo formation were referred to as the productivity of somatic embryos in this study. The regeneration frequency of each line ranged from 14 to 70 % in the cultivars and breeding populations, 12 to 92 %in the selfed progenies and 14 to 58 % in the crossed progenies of the regenerants. In the cultivars and breeding populations the increase of the regeneration frequency was independent of the increase of the productivity of somatic embryos. This result indicates that regeneration and the productivity of somatic embryos are controlled by different genetic factors. In the selfed and crossed progenies the regeneration frequency was correlated with the average number of embryos and the average stability of embryo formation (r = 0.906 and r = 0.882, respectively, significant at I o/o level). In the relationships among the three characteristics of the productivity of somatic embryos, genotypes which produced many enrbryos showed a higher stability. In the genotypes which showed a higher stability of embryo formation the score of the number of embryos and the days to embryo formation varied. It was concluded that the production of somatic embryos in alfalfa was controlled sequentially by the following factors, regeneration competency, stability of embryo formation and number of embryos. Furthermore the correlation in the selfed and crossed progenies may suggest that the productivity factor could increase the regeneration frequency.

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Linolenic acid is the unstable component of soybean [Gly- cine max (L.) Merr.] oil responsible for undesirable odors and flavors commonly associated with poor oil quality. The soybean line M-5, developed by mutagenesis from Bay, had a half of linolenic acid content compared to that of the original variety. Reciprocal crosses of both F₁ seeds and F₁ plants did not differ significantly, which indicated no maternal effect on linolenic acid content. Cytoplasmic inheritance was not observed based on the lack of reciprocal differences for linolenic acid in the analysis of both F. seeds and F2 plants. The content of linolenic acid in both F₂ seeds and plants was distributed as a trimodal pattern and the results indicated that the low, intermediate normal contents of this fatty acid were in 1 : 2 : 1 ratio. The low and intermediate linolenic acid contents in theseeds of B₁, and intermediate and normal contents in the . seeds of B₂ were fitted with the ratio of 1 : 1. These results indicated that linolenic acid in M-5 was controlled bv Materials and Methods a single major gene, acting in an additive manner. Due to the absence of maternal and cytoplasmic effects, and since a single major gene controlled the linolenic acid, the M-5 mutant could be used in a breeding program to improve the Bay (Takagi et al. 1990) was modified and renamed the variety with low linolenic acid content.

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Nitrate uptake ability from low-concentration nitrate solution was evaluated based on Michaelis-Menten kinetics in rice. In 16 cultivars, including eight japonica and eight indica, apparent Km (Michaelis constant) and apparent Vmax (maximum uptake rate) ranged from 75.7 to 130.3 μM and from 4.30 to 7.17 μmol/g fresh weight/h, respectively. There was no difference in both apparent Km and apparent Vmax between japonica and indica, suggesting that there was no intraspecific difference in the gene encoding nitrate uptake carrier. However, small differences in both apparent Km and apparent Vmax were found within each subspecies. Of four mutants related to nitrate assimilation, M605, a chlorate hypersensitive mutant, showed remarkably higher apparent Km than the original cultivar, Norin 8. This fact suggests that the nitrate uptake carrier can be altered by mutation.

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Viability of maize pollen after the drying and freezing process was estimated by its germination on maize silks. Secondly, frequencies of embryo formation were determined in crosses of hexaploid wheat with freeze-stored pollen of maize. Maize pollen germinated at frequencies ranging from 54.2 to 66.60/0 when pollen water content was reduced from 59.0% (fresh) to 9.50/0 . Pollen with a water content of 9.50/0 maintained viability and germinated at a frequency of 22.1% after four weeks of storage at - 80 °C. Embryos were successfully obtained in crosses of wheat with the maize pollen dried to 12.7 and 10.3% water content and stored for 13 weeks at - 80 °C. These embryo formation frequencies were 9.6 and 8.6% respectively. It was 22.2% in crosses with fresh pollen. All regenerated plants were wheat polyhaploids. These results suggest that stored maize pollen can be used for hexaploid wheat haploid production when and where fresh maize pollen is not available.

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Translocated chromosomes in the common wheat variety Eshimashinriki were identified, and their transmission to Japanese varieties were investigated to evaluate their breeding significance. Pairing configurations were ex-amined at the first metaphase in monotelodisomic hybrids of Eshhnashinriki with Chinese Spring ditelosomics. Eshimashinriki was confirmed to contain two independent reciprocal translocations relative to Chinese Spring, one between chromosomes 4B and 6B and another of small segments between 3B and probably 7B. According to C-banding and pairing frequencies, the breakpoints in the translocation between 4B and 6B were identified to be within the centromeric regions, giving rise to T4BS · 6BL and T4BL· 6BS. The translocation between 4B and 6B originated in the local variety Shinriki and transmitted to Eshimashinriki in the course of its breeding. Furthermore, this translocation was transmitted from Eshimashinriki to 81 % of the tested 16 varieties. Among these varieties, Saikai 102 and 12 of Norin varieties had inherited this translocation through nine different breeding cross combinations. These results indicate that the translocation between 4B and 6B of Eshimashinriki has important breeding potential resulting in its preferential transmission and maintenance in different breeding crosses. Based on the information on these varieties, yellow rust resistance, and probably adaptability and yield-improvement genes are the most possible reasons for the wide spread of this translocation. Location of these genes at the proximal region of one or both arms of the translocated chromosomes, where recombination is very rare, would insure their segregation and selection as a block with the translocated chromosomes

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A short-culm mutant line HS90, which was induced from a Japanese rice variety Gimbozu by ganuna-ray irradiation, was analyzed for the genetic factors controlling its short culmness. Compared with the original variety, HS90 has about 35 o/o reduced culm length and flowers later by a few days. The F₁' F₂ and F₃ generations of four crosses, Gimbozu X HS90, Jukkoku X Shiranui, HS90 X Jukkoku and GimbozuXJukkoku, were grown in a paddy field for genetic analysis. A variety Shiranui has already been proved to harbor a semidwarfing gene sd-1, while Jukkoku so far has been assumed to harbor sd-1 because of the cross parent of the former. In each cross, several F1 plants, about 300 F₂ plants, and 50 to 90 F₃ Iines which were raised from randomly selected F₂ plants were examined for culm length and heading date. It was clarified that the shorten-ing of HS90 is caused by an induced mutant semidwarfing gene (tentatively sd-1h ), an incomplete recessive gene identical with or allelic to sd-1 . This mutant semidwarfing gene causes remarkable reduction of culm length (ca. 35 olo) its genotypic value in the heterozygous state seems almost equal to that of the midparent. In addition, HS90 was proved to harbor another incomplete recessive semidwarfing gene (tentatively sd(t) ) non-allelic to sd-1, which was de-rived from the original variety Gimbozu. This semidwarf-ing gene reduces culm length less than sd-1h (ca. 20 olo ) : its genotypic value in the heterozygous state seemed sorne-what larger than that of the midparent. As Gimbozu and its derivative varieties have often been used as a cross parent in Japanese rice breeding, the semidwarfing gene sd(t) seemd to be widely distributed among Japanese rice varieties. The F1 plants of HS90 (sd-1h sd-1h sd(t) sd(t) ) X Gimbozu(Sd-1 Sd-1 sd(t) sd(t) ) exhibited a culm length coming within the category of semidwarfism optimum for the present cultivation methods; hence, the genotype of the F1 plants, Sd-1 sd-1h sd(t) sd(t), was considered favorable for F1 hybrid rice varieties. In this study, it was also verified that the genotype of major-genes controlling the culm length of Jukkoku is identical with that of Shiranui, which indicates that Shiranui inherited sd-1 from Jukkoku.

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Mesophyll protoplasts of tomato (Lycopersicon esculentum Mill. cv. 'Ohgata Zuiko') and Solanum lycopersicoides were fused by electrofusion method to develop fertile tetraploid somatic hybrids. Following electrofusion the protoplasts were plated in modified TM2 (MTM2) medium in which S. Iycopersicoides protoplast could not form callus. The putative hybrid calli were regenerated on MS3ZG regeneration medium in which tomato protoplasts derived calli could not regenerate shoots. Tomato protoplasts were partially inactivated with iodoacetamide (IOA) for the easy selection of heterokaryons. Three hundred regenerated plants were grovvn to maturity in a green house. The hybridity of the plants was argued by morphological, isozyme and random amplified polymorphic DNA (RAPD) analyses. All plants were heterotic in their growth, expressing an erect stem with a prominent internode like tomato, as well as days to flowering, perennial habit, free anther without sterile tip like S. Iycopersicoides. Several traits, such as leaf margin, inflorescence, flower and fruit color were intermediate between both parents. The electrophoretic pattern of PGI (.phosphoglucoisomerase), GOT (.glutamate oxaloacetate transaminase) and PG[M (phosphoglucomutase) confirmed the hybrid nature of the nuclei of all the tested plants. RAPD markers generated from 35 randomly selected plants, using eight decamer primers reconfirmed the hybrid nature of their nuclear genomes. Cyt.ological study of 20 randomly selected plants revealed 60 %of them had euploid chromosome numbers (2x=4n= 48). Tetraploid plants produced fertile pollen and developed fruits and viable seeds upon self pollination. About two thirds of the tested somatic hybrid plants survived in the winter-cold temperature (Average minimum -1.25°C) to maximum 5.3°C).

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The characteristics. of landraces of foxtail millet (Setaria italica P. Beauv.) collected in the mountainous areas of northern Pakistan were compared with Eurasian strains. Seventv-one strains from northern Pakistan were divided into three groups, the Chitral group, the Baltistan group and the Dir group according to the combination of charact.ers. The Chitral group was characterized by early heading and very short plant height. It had a large number of tillers and short conical panicles with long bristles s.imilar to those of green foxtail (S. viridis P. Beauv.), the probable ancestor of foxtail millet. The Baltistan group was distinguished by early heading, short plant height and a non-tillering habit that had only one conical panicle with short bristles. The Dir group was intermediate to late heading and tall plant height. It had a large number of tillers with long-conical panicles. Orange colored anther and elliptic grain with lucid lemma and palea lvere obs.erved in the Chitral group and the Dir group. The Baltistan group had white anther and round shaped non-lucid grain. Strains with a negative phenol color reaction were frequently found in the Chitral group and the Baltistan group. Of six strains of the Dir group examined, two showed a positive reaction but three showed a negative one. The Chitral group contained three strains with shattering habit. The distribution areas of these three groups were clearly isolated from each other. Also, these three groups had three different local names obtained bv field information. This tells. us that farmers of these areas maintain not only their specific landraces but also the names by which they are called. Comparing Eurasian strains with those grown in Kyoto, the distinctive characters of t.he Chitral group, the Baltistan group and the Dir group were similar to the strains of different regions of Eurasia. It is pointed out that these three groups of foxtail millet grown in the mountainous areas of northern Pakistan are phylogenetically distinct.

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Improvement of differential varieties is necessary, as the number of resistance genes used for breeding of blast resistance in rice increased. Establishment of new differential system is essential for population genetics and molecular genetics on host pathogen relationship. Blast fungus was collected from the ear necks of resistant varieties in several prefectures. Varieties from which the fungus was isolated were Kagahikari (Pi-i Pi-k" ) and Notohihari (('Pi-z" ) in Ishikawa Prefecture, Niigatawase ("Pi-z" or (Pi-a Pi-z" ) in Niigata Prefecture, Hatsuboshi ('Pi-i" ) in Fukushima Prefecture, Akiyutaka ((pi-k Pi-z" ) and Hanahikari ('Pi-i" ) in Yamagata Prefecture, and Yamahikari ('Pi-ta₂) in Mie, Gifu and Nagano Prefectures. These isolates were tested for pathogenicity using twelve differential varieties, and 66 races (genotypes) were obtained. When plural nonrandom associations in interactions between avirulence loci were recognized in a field, two types of interactions (cross-type and noncross-type) were always found.

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A homologous series of higher alcohols from C22 to C30 was analyzed in the waxy layer and outer rind of 15 varieties of sugarcane belonging to the genus Saccharum, and 1 variety of Sorghum bicolor. The results showed that the waxy layer contained an appreciable amount of alcohols and the dominant compound was octacosanol (C28H*<70H) except for one variety. The varietal difference of octacosanol con-tent was remarkable. The content of octacosanol in Saccharum sinensis and Sorghum bicolor was relatively low. Two varieties of Saccharum spontaneum contained more than 10 % hexacosanol (C26H530H). The total contents of higher alcohols from the outer rind were negligible, which suggested that octacosanol in the filter mud of sugar factories was derived from the waxy layer. In addition, NMR spectra indicated that octacosanol predominated among the soluble compounds in organic solvents.

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