Genetrcally fixed "7S-low lines" were developed from a cross Keburi × F1 (Oodate No. 1 × Mo-shi-dou Gong 503) in soybean. Seven S-low lines are characterized by the lack of the α'-subunit of 7S globulin and a marked decrease of both the α- and β-subunits of 7S globulin due to the simultaneous incorporation of α'-null, α-low and β-low alleles. The 7S-low lines and ordinary varieties were examined for their respective contents of 7 S and 11S globulins, total protein contents, development of protein bodies and amino acid composition in the mature seeds. The contents of 7S globulin in the 7S-low lines were only half of those in the ordlnary varieties, whereas the contents of 11S globulin in the lines were about 14% higher than those in the ordinary varieties. The marked modifications in the protein compositlon of the seeds did not adversely affect the total protein contents as well as de-velopment and morphology of the protein bodies. A high negative correlation was found be-tween the 7S and 11S globulin contents (r= -0.84, P{r=0}0.001), and the calculated absolute value of the slope of the regression line was slightly larger than 1.0 (a=-1.5). These results suggest that 11S globulin may compensate for the decrease in 7S globulin to maintain the production of total seed protein in the 7S-low lines. The mean value of the sulfur-containing amino acid contents in the seeds of four representative 7S-low lines was about 20% higher than that of four ordinary varieties.

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The varietal differences in embryogenic ability in anther culture of Chinese cabbage, Brassica campestris ssp. pekinensis, were investigated. In the first experiment, the anthers of B. campestris were incubated in the modified B5 medium (KELLER and ARMSTRONG 1979) at 30°C for 14 days and then maintained at 25°C in the dark. Only a few embryos were ob-served in a limited number of cultivars in this treatment. In contrast, embryos were formed efficiently by the treatment at 35'C for one day. The embryogenic ability from anthers was remarkably different among the cultivars. Among the cultivars of B. campestris, the anthers of 'ASO Ichigo' belonging to the Kenshin group produced embryos most efficiently. The second experiment was conducted to know the embryogenic ability of cultivars in the Kenshin group. Although some varietal differences in the embryogenic ability were observed, one of the cultivars exhibited the highest culture efficiency (expected yield of embryos from 1, 000 anthers cultured) of over 10, 000. Comparing the data of two experiments, the Kenshin group were thought to have a high embryogenic ability in anther culture of Chinese cabbage.

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To verify the habitat segregation of Echinochloa weeds into flooded rice paddies and unflooded uplands, about 200 accessions of the weeds were field-collected at various locations in Kyoto and Shiga Prefectures. Sixty six of the 68 accessions of E, oryzicola and E, crusgalli var. formosensis in total were present in flooded rice paddies, while 56 of the 60 accessions of E. crus-galli var. praticola at habitats of upland conditions. E. crus-galli var. crus-galli showed no specific habitats and distributed throughout the habitats we surveyed. In pot experiments with one strain each of the weeds, either E. oryzicola or E. crus-galli var. formosensis was little affected in seed germination and seedling growih under 10 and 15cm flooding and the seeds germinated even under nitrogen. However, no seeds of E. crus-galli var. praticola virtually germinated either under flooding at 5 cm depth or nitrogen atomosphere and the seedlings stunted in height when the post-germinating seeds were sowed under flooding. Seed germination and seedling growth of E. crus-galli var. crus-galli were also adversely affected under flooding and nitrogen atmosphere, but not as greatly as those of E. crus-galli var. praticola. These results and the Km values of seeds in oxygen uptake suggested that the incapability of anaerobic germination constitute the primary physiological barrier(s) against its invation into flooded rice.

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Anthers of Poncirus tnfoliata and Citrus aurantium cultured on agar inedia were cytologically examined at three-day intervals for microspore dedifferentiation. The results proved that plantlets obtained by anther culture of these citrus originated from microspores. Microspore development in vitro followed three main routes. In route A and B, microspores ultimately lost their contents. In route C, multi-nucleate-cellular structures developed into microspore embryoids. In this route C, microspores showed abnormal nuclear division; one route (C₁), produced two types of morphologically similar nuclei which were rather large or small and classified as 'vegetative-type' (C₁a) or 'generative-type' nuclei (C₁b) respective-ly. The other route (C₂), produced 'vegetative-type' and rather small 'generative-type' nuclei. Route C₂ diverged to two routes, C₂a and C₂b. In C\2a, only a 'vegetative-type' nucleus divided repeatedly whereas route C₂b showed independent division of both 'vegeta-tive' and 'generative-type' nuclei. That is, repeated division of both 'vegetative' and 'generative-type' nuclei independently of each other contributed to the formation of microspore embryoids in citrus anther culture. Of these pathways, the route C2 may be the most responsible for the embryoid formation. Nuclear fusion occurred in route C and appeared to contribute to ploidy variation. Calli which appeared from the inside of the anthers originated from both anther wall and microspores. Embryoids derived from somatic tissue of anthers were not observed.

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Southern blot analysis was used to identify differences in the characteristics of mitochondrial DNAs (mtDNAs) of rice with normal and male-sterile cytoplasms. Six oligonucleotides, coding for parts of plant mitochondrial proteins, were chemically synthesized and used as hybridization probes. In the restriction enzyme digested mtDNAS from normal and cms-Bo male-sterile cytoplasms, signals homologous to a probe for an apocylochrome b (cob) or an ATPase subunit 6 (atp6) gene were different in electrophoretic mobility between the two cytoplasms. Furthermore, the copy number of the two genes were considered to be twice as many in the mtDNAs of cms-Bo cytoplasm than that of normal cytoplasm. In four other DNA probes for a cytochrome oxidase subunit II, a cytochrome oxidase subunit I, a F₁-ATPase a subunit, and an ATPase subunit 9 gene, no differential gene organization was observed between the two cytoplasms. Restriction fragment length polymorphisms in the probes for the cob and apt6 genes were observed among mtDNAs from six strains of cyioplasmically male-sterile rice. These results indicate a genetic divergence of rice mtDNA, and suggest that the gene rearrangements around tbe cob and atp6 genes of mtDNA, together with the duplication of the two genes, were brought about in some of the male-sterile cytoplasms during the domestication of rice.

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The present study was undertaken in order to clarify the effect of the culture media and the genotypes on the regeneration of green plantlets from pollen embryoids by anther culture of Japanese wheat cultivars. Pollen embryoids of 4 cultivars produced on Potato-2 medium were transferred onto two kinds of regeneration media (Table 1). On both media, embryoids grew into calli and then regenerated green or albino shoots and/or roots (Fig. 1 b and c). In rare cases, embryoids germinated (Fig. 1 a). The frequencies of green plantlets regenerated from embryoids differed with their genotypes even in the regeneration medium from 2.8% in Nanbukomugi to 33.5% in Chinese Spring. Moreover, the ability of embryoids to regenerate green plantlets was not affected by anther culture media, Potato-2 and C₁ medium (Table 2). The effects of abscisic acid (ABA) on the embryoid formation and green plantlet regeneration were studied in anther culture of 7 cultivars (Table 3). ABA at a low concentration (0.1 and 0.5mg/l) had a stimulatory effect on the embryo formation in some cultivars which were genotypes of a rather low ability in embryoid formation, while ABA had a suppressive effect in other cultivars. However, ABA did not show a stimulatory effect on the regeneration of green plantlets in all cultivars tested. In conclusion, the ability of the green plantlet regeneration depended on genotypes regardless of the anther culture and regeneration media tested in this study: Norin 12 and Chinese Spring showed relatively high frequency of the green plantlet regeneration, while Hachimankornugi, Kitakarnikornugi and Norin 61 did not regenerate green plantlets. On chromosome constitutions of the regenerated green plants almost 659 were haploid (2n=21) and about 35% were diploid (2n=42) (Table 4, Fig. 2).

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Wet endurance in F₁ hybrids and F₂ populations and the heritability in early generations in barley were estimated to improve wet endurance of malting barley. Materials were grown under excess soil moisture treatment (irrigated condition) at the internode elongation stage. Selection character for wet endurance was degree of dead leaf expressed by the score 0 (most tolerant)∼5(most susceptible) under excess soil moisture treatment, because degree of dead leaf under excess soil moisture treatment showed signifi-cant correlation to the reduction ratios of grain yield per plant and culm length by the treat-ment (the mean value of excess soil moisture plot/that of control plot). Mean damages of F₁ hybrids (5 cross cornbinations) under excess soil moisture treatment were less than those of their midparents, indicating the heterosis of wet endurance. Frequency distributions of the degree of dead leaf in F₂ populations under excess soil moisture treatment showed continuous variation. Therefore, wet endurance of barley seerns to be due to the effect of polygene.

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The authors developed new inoculation methods and evaluated approximately five thousand barley verieties for screening resistant varieti.es to Fusarium head blight or scab. For the first mass selection, the 'cut-spike' inoculation method was applied: At the time of flowering, spikes were taken off frorn the plants at the second internodes, arranged in pans with overflowing water and were inoculated with an ascospore suspension of Gibberella zeae. Spikes were kept at 25°C and at 100% humidity for two days after inoculation, and then transferred to a growth chamber where the temperature and humidity were controlled at 23-13°C (with a sine curve) and about 95%, respectively. Illumination was 5, 000-10, 000 lux during 14 hours a day. Eight days after inoculation, the reaction of the varieties to the causal fungus was scored from 0 to 8 according to the infected spikelet percentage (Tables 1 and 2). Varietal differences in the scores were highly siguificant, indicating the efficiency of the inoculation method (Table 4). Varieties with the score of less than 4 were resistant and those with more than 4 were susceptible in the field conditions (Table 5).

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Self-compatibility, shoot-regeneration ability and embryoid formation in the first backcross generation (B₁F₁) between cultivated tomatoes of Lycopersicon esculentum and a wild species L, per, var. glandulosum were studied for the programme of transferring the high shoot-regeneration ability of L. per. var. glandulosum into L. esculentum. Self-compatibility in each B₁F₁ plant was assessed by fruit set and seed content that were determined by observing the B₁F₁ plants which flowered in the field and of which fruits were set under open pollination. From the results, three B₁F₁ plants were selected as completely self-compatible ones because they showed sufEicient fruit set and seed content. Shoot-regeneration ability was compared among eight BIFI plants together with a cultivated tomato, a wild species L. per. var. glalrdulosum and their F₁ by means of in vitro culture of leaf segment. The results revealed that, with respect to shoot-regeneration ability, L. per. var. glalrdulosum was completely dominant against cultivated tomato and eight B₁F₁ plants segregated with a wide range of variation from plants nearer to L. per. var. glandulosum to those to cultivated tomato. Totally B₁F₁ plants were rather close to L. per. var. glandulosum. Two out of the three self-compatible plants were estimated to have a higher shoot-regeneration ability than cultivated tomato. In the experiment for embryoid formation, one self-incompatible B1F1 plant was used. Callus cells derived from leaf were cultured in suspension in 8E media supplmented with low concentrations of auxin and, subsequently, small masses of cells in size of 350∼850 um were cultured on MS agar medium supplemented with 1.0mg/l ZR. Embryoids began to appear in 15∼20 days. This confirms that som.e of the genes responsible for em-bryoid formation in L. per. var. glandulosum are transmitted to the first backcross genera-tion between L. esculentum and L. per. var. glavrdulosum. In addition to the conclusion, this experiment could also deepen the understanding about plant hormones, NAA and 2, 4-D, which added to the suspensio medium and ZR to the medium for embryoid formation.

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Mesophyll protoplasts of black mustard and Hakuran were fused by the PEG-high pH ?? igh Ca method. Out of six plants regenerated, one showed hybrid morphology. The hybridity was ascertained by the isozyme pattern of acid phosphatase and chromosome number. This hybrid was estimated to be a trigenomic hexaploid having A. B and C genomes, and showed similar male sterility to Hakuran.

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Difficulty in F₁ seed production in carrot has resulted in a much more delayed release of F1 varieties than in other major vegetables. In Japan, F₁ varieties outnumbered the open-pollinated ones among the new varieties of carrot released during the period 1981-1987. In USSR, in spite of the active promotion of the use oi male sterility, F₁ varieties do not prevail in commercial fields. F₁ varieties of carrot are superior in yield, growih vigour, uniformity of top growih and root size and disease resistance. New methods involving biotechnology, especially tissue culture including synthetic seeds, are likely to play a major role in the breeding and propagation of F₁ varieties.

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