M₂ populations of rice used in the present experiments originated from seeds of a Japanese cultivar, Harebare, treated with ethyleneimine and ethyl-methan-sulfonate. These plants were grown under different conditions in terms of planting time and amount of nitrogen fertilizer applied. Frequency distribution of M₂ plants for heading time was affected by the planting time and the amount of nitrogen fertilizer applied. Selection efficiency for early heading of the M₂ plants was the highest in the case of normal planting time, and the, Iowest in the case of late planting. Mechanisms controlling the changes in the selection efficiency for heading time are briefly discussed.

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The relationship of 9 Medicago species belonging to 4 subgenera was analyzed by using restriction fragment length polymorphism (RFLP) methodologies. We analyzed 85-132 RFLP band patterns, which were caused by chloroplast DNA variations, to estimate the genetic distance among the species. These species were clustered together at around 0.1 to 0.4 Ievel of distance for marker, indicating that the Medicago species have a large genetic similarity. The most similar species were M. Iittoralis and M. truncatula and the most dissimilar one was M. Iupulina. The cluster analysis based on RFLP band patterns differentiated 9 species in another 4 groups: a) M. Iittoralis. M. truncatula, M. scutellata and M. sativa ; b) M. orbicularis and M. radiata ; c) M. rigidula and M. minima ; d) M. Iupulina. Comparing the previous classification of Medicago species with that in this study, there are two discrepancies; M. Iupulina is the most distant species from others and M. sativa (subgenus M:edicago) was closely clustered with M. scutellata. M. Iittoralis and M. truncatula classified in subgenus Spirocarpos.

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We report the inheritance of the 11S globulin (glycinin) subunits and results of evaluating progenies lacl(ing these subunits in order to breed soybean varieties having different glycinin subunit compositions. F₂ seeds from a cross between a mutant soybean line lacking group I (A₁*B₂, A₁bB₁b and A₂B₁*) and A₅A₄B₃ subunits and a wild soy-bean (Glycine soja) accession lacking A₃B₄ subunit were examined for glycinin subunits by SDS-PAGE. The segregation for the presence or absence of the glycinin sub-units fitted well for independent inheritance among the three loci containing the group I, A₅A₄B₃ and A₃B₄ sub-unit genes, respectively. Due to this fact, we propose here that the group 11 including A₅A₄B₃ and A₃B₄ subunits can be classified into two subgroups, IIa (A5A4B3 subunit) and IIb (A₃B₄ subunit). F₁ plants obtained from a cross between cv.

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Some characteristics of interspecific hybrid plants between Allium chinense and some other edible Allium species were surveyed. Interspecific hybrid plants between Allium chinense and A. tistulosum, were similar to A. chinense in morphological appearance. All the hybrid plants formed white-colored bulbs similar to those in A. chinense. Bulb weight varied widely, ranging from 1.6 g to 49.0 g with an average value of 15.8 g. The average weight of the hybrid(15.8 g) was much greater than that of A. chinense (8.1 g). The average value of total bulb weight per hybrid plant was 104.3 g, again significantly higher than 68.9 g in A. chinense. Multiplication in the hybrid plants also ranged widely from 1.5 to 21.5, and the average value of 6.6 in hybrid plants was intermediate between both parents. Flowering time in the hybrid plants was June to August, which was intermediate between both parents.

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Germination ability of rice seeds at a low temperature varies with the cultivars. However, the biochemical mechanism of this difference has not been clarified. To analyze the role of active oxygen-scavegning enzymes in germination at a low temperature, calatase activity in rice seed embryo was determined. The specific activity of catalase increased during germination and the rate of increase was high in cultivars with a high germination ability at a low temperature. Catalase activity was detected even in the embryo of dry seeds (before imbibition). This initial level of catalase also varied with the cultivars and there was a positive correlation between initial level of catalase activity and germination rate at a low temperature. Such a relation was not observed between the superoxide dismutase activity of dry seed embryo and germination rate at a low temperature. It was also found that cultivars with a high initial level of catalase activity in the embryo could germinate even in a 3 % hydrogen peroxide solution. These charac-teristics reflect one of the genetic traits of rice.

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Amphidiploid plants were obtained by colchicine treatuent of an interspecific hybrid between N. trigonophylla (2n= 24) and N. tabacum (2n = 48) that had been produced through ovule culture. Eight colchicine-treated plantlets were found tp be amphidiploids with a chromosome number of 2n=72, namely, the sum of the chromosome numbers of the two parents. The plant, flowers and leaves of the amphidiploids were morphologically similar to those of un-treated F1 plants, which had characteristics intermediate between those of the parents. Even though pollen fertility was high (more than 90% ), only about 1.5% of the ovules developed into viable seeds. From histological observations of selfed amphidiploids, we found that the fertilized ovule ratio was also low (12-14% ) although the embryo sacs appeared normal. The low seed set percentage was mainly due to the fact that most of the pollen tubes terminated in the style and very few pollen tubes were observed in the ovarian cavity.

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cDNA Iibraries were constructed from poly(A)+RNAs that had been isolated from calli 7 days after induction of regeneration on two different media, namely, embryogenesis-inducing medium and organogenesis-inducing medium. Differential screening of the libraries with cDNA probes prepared from unorganized calli and from calli that had been induced to undergo somatic embryogenesis and orga-nogenesis (formation of adventitious shoots) allowed us to identify a CDNA clone, pRSEM1, that was specific to regeneration. Analysis of the temporal accumulation of the mRNA that corresponded to pRSEMI during

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In order to detect mobility variants of soybean Kunitz trypsin inhibitor (SKTI) proteins, we developed a large slab gel method (18.5 cm long X 14.5 cm wide) of elec-trophoresis, and analyzed 173 cultivars of soybeans (Glycine max ) from Japan and China, and 62 populations of wild soybeans (G. soja ) collected from all over lwate Prefecture, Japan. As a result of this electrophoretic survey, two new mobility variants were discovered: a variant showing a slightly slower mobility than the Tia type (tentatively designated as Tia-s ) in a wild soybean line and another variant with a slightly faster mobility than the Tib type (tentatively designated as Tib-f) in a cultivated soybean variety. Transmissibility of this variation to consecutive generations was confirmed by parent-offspring tests and hybridization tests using the variants and/or the common types. Isoelectric focusing (IEF) test applied to these two variants revealed differences in the location of the isoelet-ric points in the gel. Significance of these discoveries was discussed.

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Reciprocal crosses were made to analyze the intergeneric crossability and to obtain intergeneric hybrids between Raphauus sativus and four Sinapis species (S. alba. S. arvensis. S. pubescens and S. turgida ). Pollen germination in the pistil and development of hybrid embryos depended on the direction of each cross. The crossability was relatively higher when Sinapis species were used as pistillate parents, whereas S. pubescens was compatible with R. sativus only when used as pollen parent. By embryo rescue technique and/or conventional method, hybrid plants were produced in all intergeneric crosses between R. sativus and four species of Sinapis except for the cross of S. pubesceus x R. sativus due to strong prefertilization barriers. When Sinapis species were used as pistillate parents,

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In order to improve the nutritional value of soybean protein through the decrease of the β-conglycinin content or increase of the glycinin content, 3, 000 dry seeds of a culti-var 'Wasesuzunari' were treated with 10 to 50 kR y -rays. The 3, 500 M2 seeds were observed for the analysis of the protein composition of the mutants by SDS-PAGE. As a result, a mutant trait characterized by the lack of both the α and β subunits of β-conglycinin and lethal chiorosis was detected. Investigation on the segregation of the mutant trait was carried out from the M3 to M8 generations and a peculiar segregation ratio (3 normal : 4 with half the amount : I null for the α, β subunits) was obtained from heterozygous individuals from the previous generations.

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Methods of discrimination of indica and japonica rice based on the shape of silica body from motor cells in the leaf blade and on morphological and physiological characters of grain were compared, and their relationship was investigated. Fifty Chinese native and im-proved rice varieties (25 Hsien and 25 Keng) were used. Four morphological characters of silica body from the motor cells (vertical length, VL; horizontal length, HL; Iateral length, LL and shape coefficient b/a) (Fig. 1), grain shape (length, L; width, W and their ratio L/W), apiculus hair length (AH), phenol reaction of the hull (PR) and potassium chlorate (KCI03) resist-ance of seedlings (KC) based on injury scores (O to 3) were analysed. Based on the above characters of indica and japonica cultivars defined by Sato's discriminant function (Z (SD) =PR+1.313KC-0.82AH-1.251)

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A total of 48 two-rowed barley varieties with various percentage of hull-cracked t5crrains which reduce the germinability of malting barley grains, was examined in Kurashiki and Gunma both in 1992 and 1993 with two replications. Percentage of hull-cracked grains and thousand kernel weight were recorded (Table 1). Be sides, progenitors of Yoshikei 16 and Nittakei 22, whose hullcracked grain percentage was extremely high, were examined in Gunma in 1992 and 1993 for analyzing the inheritance of the trait.

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We have developed a package of computer programs named GEST which can be used for analysis of genotype X environment interaction and stability of crop plants. The prolgrams are written entirely in N88-BASIC under IVIS-DOS operatintg system which can be run on an NEC micro-computer. GEST (Ver. 1.0) is composed of 6

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The objectives of this study were to analyze the genetic system controlling days to flowering in soybean under shortday conditions and to identify microsatellite DNA Ioci linked to the gene controlling the trait using the cross between cv. Heihe 5 and Akisengoku which differ in photo-period sensitivity. Sixty six F₂ individuals were grown under 11.5 h photoperiod in a chamber. The results of the experiment showed that days to flowering was controlled by a major gene, and earliness was partially dominant to lateness. Based on genetic marker analysis in the F₂ generation, a gene locus associated with days to flowering was found to be located between two microsatellite DNA markers, (AAT)-2800 and (AAT)-3700.

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