The utilization of germplasm of the wild species in sweet-potato breeding has been conducted for the last three decades. Such attempts brought some remarkable achievments in improving root yield, starch content and resistance to the nematodes of sweet potato. Some wild plants in polyploid series may have many genes potentially important for further improvement of the agronomic traits. However, the genomic relationship between the wild relatives and hexaploid sweet potato (2n=6x=90) has been unrevealed. Meiotic studies were carried out on the hexaploids synthesized with diploids and tetraploids and on the F₁ hybrids, when possible, with sweet potato. Chromosomes in pollen mother cells (PMC's) and root tip cells were fixed in New-comer's solution and stained according to Feulgen reaction with Schiff's reagent. The present report was concerned wlth two kinds of the synthetic hexaploids. The first was the hexaploids derived from chromosome doubling of triploid hybrids between Ipomoea lacunosa (K61, 2n=30) and I.tiliacea (K134, 2n=60). the synthetic hexaploid exhibited mostly regular meiosis with bivalents at the metaphase I stage (MI), and it was considered an allo- or segmental allo-hexaploid. The synthetic hexaploids were fertile, but failure in obtaining hybrids by crosses with sweet potato suggested a critical reproductive barrier between them. The second synthetic hexaploids with 2x I, trifida (K221, 2n=30) and 4x I, trifida (K233, 2n=60) showed the chromosome configurations characterized by the occurrence of tetravalents and hexavalents. Such multivalent associations, high in frequency and number per cell, suggested the presence of the genomes at least in quadruplicate. Similar pattern of the chromosome configura-tions was observed in a cultivar of sweet potato and the F₁ hybrid between the synthetic hexaploid and sweet potato. Consequently, the genomic formula for sweet potato was proposed as B1B1B2B2B2B2, in which B1B1 was given to 2x I.trifida and B2B2B2B2 to 4x I. trifida. However, it is necessary to clarify the degree of homology between B1 and B2 genomes for more conclusive genomic constitution of sweet potato. A brief account was given for the taxonomic identification of the wild Ipomoea strains used in the present study.

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Leaf isozymes of four enzymes in citrus were analyzed using polyacrylamide gel electrophoresis to demonstrate the phylogenic relationship of the cultivars. Two loci for the superoxide dismutase(SOD) (EC1.15.1.1), one locus for the peroxidase (EC 1.11.1.7) and polyphenol oxidase (EC1.10.3.2), respectively were examined. In addition to the two loci of glutamate oxal-acetate transaminase(GOT) (EC2.6.1.1), reported in the former study, a new locus was detected in the present report. These experiments suggest that the mandarin cultivars originated from three genetic sources ; Indian, Chinese, and Japanese ones. Most of the Chinese mandarins including 'Kinokuni' showed identical genotypes, while the 'Ponkan' and 'Dancy tangerine' differed from the Chinese cultivars in their genotypes at the Px locus, and they were assumed to have originated from India as suggested by T. Tanaka. On the other hand, the Japanese mandarins were considered to be genetically affected by the'Chinese mandarins. But some of the Japanese mandarins including 'Yatsushiro' and 'Koji' exhibited genetic effects from Tachibana, the wild type of the mandarin in J.apan. The genotypes of the sweet orange cultivars were homogeneous and similar to those 0L the Chinese mandarins. Sour orange was heterozygous at several loci, and was assumed to be a hybrid between mandarin and pummelo. Among the pummelo cultivars, some heterogeneity was detected at some loci.

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Simple and efficient protoplast culture procedure of eggplant was developed. Protoplasts were isolated from hypocotyls by the treatment with 0.067% Macerozyme R-10 and 0.33% Meicelase for 16 h at 25°C, and cultured in the medium with l/2 MS salts (200 mg/l NH4NO3), 1/2 MS vitamins, 1 mg/l 2, 4-D, 1 mg/l NAA, 1 mg/l kinetin, 1% sucrose and 0.3 to 0.5M mannitol. Auxin concentrations were reduced by the addition of the same medium without auxins at weekly intervals and finally to 0.1 mg/l of 2, 4-D and NAA. Mannitol concentration was also reduced gradually. Calluses larger than 3 mm were transferred to the MS medium with 0.2 mg/l IAA and 1 or 3 mg/l zeatin, which gave the highest shoot regeneration frequency. Elongated shoots were cultured in the MS Iiquid medium with 1 mg/l NAA for two days and transferred to the MS agar medium without hormones to regenerate roots. This culture procedure was applied to the protoplasts of various eggplant cultivars. Varietal differences were observed in the efflciency of colony formation and shoot regeneration. Regenerated plants were obtained efficiently from the protoplasts of 'Koushien', 'Khatkhatia long' and Solanum insanum.

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The effect of chromosomes 2D and 2R on the seed fertility of hexaploid triticale was investigated to know whether 2D is responsible for the high seed fertility which causes the preferential chromosome substitution of 2D for 2R. Using three parental lines ; (1) S78, a hexaploid substitutional triticale line (genome formula, AABBR'R') with aestivum (aes) cytoplasm, where R' stands for 2D-2R substitution in R genome, (2) Beagle, a hexaploid line (AABBRR) and (3) (cer)-JM135, a hexaploid line (AABBRR) with cereale (cer) cytoplasm, crossings were made between S 78 and Beagle, and (cer)-JM135 and S 78. Combining the two cytoplasms, (aes) and (cer), and the two genome canstitutions, AABBRR and AABBR'R', plants of four nucleo-cytoplasmic genotypes, (aes)-AABBRR, (aes)-AABBR'R', (cer)-AABBRR and (cer)-AABBR'R' were identified at the F₂ and F₃ generations and their seed fertilities were examined. Marked relatioriships between the four genotypes and their seed fertilities were found as follows : (1) chromosome 2D gave high seed fertility in (aes) cytoplasm but low seed fertility in (cer) cytoplasm, (2) chromosome 2R gave both low and high seed fertility in (aes) and (cer) cytoplasm, however, 2R was necessary to high seed fertility in (cer) cytoplasm (Fig. 2). The results indicated that the favorable effect of 2D over 2R on the seed fertility under (aes) cytoplasm resulted in the 2D-2R substitution in secondary hexaploid triticale.

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Immature barley embryos in culture show a high ability of plant regeneration, but the period in which embryos can be used is limited. To overcome this difiiculty, regeneration of shoots from callus cultures derived from seeds and mature embryos detached from seeds was attempted, using 16 six-rowed and 4 two-rowed varieties of barley. Callus was initiated from seeds and mature embryos cultured on B 5 medium with 2, 4-D at concentrations ranging from 5 to 100μM and then allowed to grow on the same medium for two months. Regeneration of plants was observed in two varieties Golden Grain and Haisa 4X when 2, 4-D at concentrations of 10 and 30μM was used for the culture of calli derived from seeds and in one variety Golden Promise at concentrations of 10 and 15μM for the culture of calli derived from mature embryos. It must be noted that regeneration of plants occurred on medium with high concentrations of 2, 4-D.

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In Japanese two-rowed barley varieties, there are 4 genotypes for esterase isozymes at 3 loci (Est1' Est2 and Est4) which are closely linked as a gene block at the terminal of the long arm of chromosome 3. The genotypes are Pr-Fr-Su, Ca-Dr-Nz, Ca-Fr-Su and Ca-Fr-At which consist of different allelic c.ombinations at 3 loci, Est1-Est2-Est4, respectively, and most of the varieties have either Pr-Fr-Su or Ca-Dr-Nz genotype. While the varieties which are old or introduced ones in the early 20 century, for instance, Golden Melon, have mainly the Ca-Dr-Nz genotype, the Pr-Fr-Su genotypes are frequently found in improved varieties. Thus, the varieties with the Pr-Fr-Su genotype which was derived from Prior occupy the major acreage of two-rowed barley cultivation at present (Figs. 2 and 3).

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In order to make selection on the malting quality of malting barley in early generations, it was examined the possibility of evaluating the malting quality by head type and kernel appearance. Materials were F₃, F₄ and F₆ lines that one of parents was high quality line, Nitta Nijo 1 (named to Haruna Nijo in 1979). As an inex of head type, spike density was used. And as an index of kernel appearance, volume of wrinkles on husks was used. Volume of wrinkles on husks was judged by panel test. Consequently high rank correlation coefficients between panelers (r=0.6 over) were obtained in mid generations. In eary generations those were slightly low. Calculating correlations between spike density and volume of wrinkles on husks with malting quality, positive correlations were obtained between volume of wrinkles on husks and malt extract, extract yield, examination marks, especially high for malt extract. However no relationship was found between spike density and malting quality. Somewhat high relationships were obtained between generations in spike density, volume of wrinkles on husks, malt extract and examination marks. It was estimated that high malt extract could be selected easily by judgement of volume 0L wrinkles on husks. Consequently it was expected that this method would be effective for the selecting of high malt extract lines in early-mid generations of handling much of materials.

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The variation of heading time in the hybrids of the cross between a Japanese rice variety Koshihikari and a U.S.A. rice variety Saturn was genetically analyzed by use of close linkage with the gene for resistance to blast disease. The experiments were conducted in the central part of Japan at 350' North Latitude. Saturn and Koshihikari headed 95 and 98 days after sowing, respectively, and their F₁ hybrids headed 9 days later than Koshihikari. The F₂ population showed a bimodal distribution and transgressive segregation for earlier and later heading (Fig. 1). The majority of the BC1F₁[S](P1/P2/P2) plants headed as early as the recurrent parent Saturn with some plants heading later, while the BC1F₁[K](P1/P2/P1) showed relatively larger variations and the convergence was not remarkable even by backcrossing with Koshihikari. The plants of the three hybrid populations were divided into early and late groups on the 101 st day that separated the heading time of the F₁ from that of the parents. These variations showed a good fit to the segregation ratios that were attributed to three gene pairs (Table 1).

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Artificially induced amphihaploid or amphidiploid Raphanobrassica (2n=18 or 2n=36, RC or RRCC) between radish (Raphanus sativus L., 2n=18, RR) and ornamental kale (Brassica oleracea L., 2n=18, CC) are favorable bridge plants in transferring some agronomic characteristics from one parental species to the other (NAMAI 1976, SARASHIMA & MATSUZAWA 1979). The chromosome addition lines of radish with single kale chromosome may provide an useful material for this breeding program. In this paper, cytological and morphological observations were made on the successive progenies which were derived from crossing of amphidiploid Raphanobrassica with radish, and then seven types of chromosome addition lines (2n=19) of radish with single kale chromosome were bred. Female parents used in the first generation were Rb-63 and Rb-74 lines of Raphanobrassica (2n=36, RRCC) which were bred by R. sativus L., (2n=18, RR)×B.oleracea L., var. acephala (2n=18, CC) (MATSUZAWA et al. 1985). Male parents were the same cultivars of Japanese radish as the female parent of Raphanobrassica.

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There has been some inconsistencies in pollination requirement of Brassica juncea which is considered to be self-compatible and to set seeds well without insect pollinators (FREE and SPENCER-BOOTH 1963) and also with insect pollinators in isolation cages (NAMAI 1983 b). In this paper, we reported the relationships among the number of insect pollinators, the number of pollen grains deposited on the stigma and seed set percentage in caged B.juncea (L) Coss., digenomic (AABB), self-compatible and self-fertilizing species, in comparison with B.campestris, monogenomic (AA), self-incompatible and outcrossing species.

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Shoot tips 0.5mm long were taken from actively growing almond (Prunus amygdalus Batsch cv. hardy) shoots. These were cultured on the modified 1/2 MS medium (UEMATSU and AKIHAMA 1987) supplemented with 6-benzyladenin (6-BA) or N-(2-chloro-4-pyridyl)-N-phenylurea (4PU, Kyowahakko Kogyo K. K.). About 70 to 80% of shoots survived on the paper-wick liquid medium containing 2.0 or 4.0 mg/l 4PU. Growing shoots were transferred to the solid multiplying medium containing 2g/l gerlite and 0.5mg/l 6-BA. These shoots were subcultured on the same fresh medium at forty days intervals. After nine months of culture, the multiplication rate was 6.6-fold per L0rty days. The longest shoot reached to 3.8cm. Within a month after transferring to the rooting medium containing 0.5mg/l naphthalene aceticacid (NAA), root induction occurred.

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Breeding of a restorer line for the male-sterile cytoplasm [ms-CW] of wild rice (W 1 ; Oryza rufipogon Griff.), identified by KATSUO and MIZUSHIMA (1958), was demon-strated by transferring the restoring gene(s) of W 1 to a cultivar through anther culture. Anthers of the F₁ hybrid between W I (=) and O. sativa L. cv. Somewake (=) were cultured and two regenerated plants with high pollen stainability were obtained. Of these two plants, one was sterile in seed set, but the other (A₁) was fertile and its selfed progenies (A₂) also showed a high seed fertility. In a test cross of one of A 2 plants (=) with a cytoplasmic male-sterile strain carrying the cytoplasm of W₁ and the nucleus of cv. Reimei, the resulting F₁ gave a high seed fertility, demonstrating that the regenerated plant (A1) possessed restorer gene(s). The F₂ and BIFI progenies of W₁ (=)/Somewake in the conventional crossing showed a wide variation in pollen stainability and seed fertility, that might be due to not only cytoplasmic but also genic hybrid sterility. These results suggest that anther culture is effectively utilized for breeding restorer lines from remote hybrids, especially when they suffer from hybrid sterility.

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Frequencies of haploid production in wheat were compared between the two methods of anther culture and intergeneric crossing with Hordeum bulbosum L. using three varieties and their reciprocal F₁ hybrids. Average frequencies of embryo and plant production per 100 florets were 5. 02 embryoids and 1.27 plants (including 0.76 albino plants) through the anther culture technique, 55.0 embryos and 39. 4 green plants through the bulbosum technique, indicating that the bulbosum technique was obviously much more efficient. Problems to be solved for applying both methods to all the wheat genotypes were discussed.

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