A shattering resistance gene in a mutant line, SR-5, induced from an indica rice variety, Nan-jing11 was mapped on chromosome 3 based on QTL (Quantitative Trait Locus) analysis using RFLP markers, and it was designated as sh4. Seventy eight plants of the F₂ population derived from a cross between a javanica (tropical japonica) rice variety Dinalaga with shattering habit and SR-5 were investigated for the degree of shattering and marker genotypes by RFLP. The results of QTL analysis suggested that sh4 was located at the same position as that of an RFLP marker R250 on chromosome 3. In the F₂ population, the shattering degree showed a continuous distribution including transgressive segregation covering wider ranges of prone and resistance to shattering compared with parental variations. The variance explained (R²) at sh4 showed a lower value than the heritability (h²) of tbe shattering degree in the F₂ population. Based on the results of QTL analysis in the region on chromosome 1 where the shattering gene, sh2 and a single recessive shattering resistance gene in a mutant line SR-1, induced from an indica rice variety Nan-jing11, were localted, it was confirmed that these loci were not related to the segregation in the F₂ population. It was also suggested tbat in addition to sh4, other factors may control the trait.

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In order to study the relationship between the diversity of rice cultivar groups carrying different resistant genes to bacterial blight(BB) and Indica-Japonica classification, the Indica (Z≤O) and Japonica (O<Z) types defined by the discriminant Z-function (Sato 1991) were studied for the BB resistant groups in relation to the isozyme types. Based on the combination of phenol reaction(Ph), KCIO₃ resistance(K) and apiculus hair length(H), the 832 cultivars were classified into Indica and Japonica types. Among the total cultivars, it was found that the distribution of Z score in the range from -1.8 to 2.0 formed three peaks:one peak (Z≤O) corresponding to Japonica type, and two peaks (O<Z≤1.4, 1.4<Z) corresponding to Indica type.Cultivars showing Ph-negative and K-susceptible tended to form the peak of O<Z≤1.4, and this peak was not the minority in the BB resistant groups. Therefore, the peaks of O<Z≤1.4 and 1.4<Z were tentatively separated as Interrnediate and Indica types respectively. In the Java 14 group, almost 80% consisted of isozyme type VI, and the type VI was composed of both Japonica and Intermediate types with an even balance. The TKM 6 and Cas 209 groups consisted of isozyme type I, and almost all cultivars were Indica and Intermediate types. The DZ 192 group consisted of type II, and typeII was also classified as Indica and Intermediate types. The TN 1 group involved type I predominantly and a small group of type VI as well. In this group, most cultivars of type VI were Japonica type, while Intermediate type was frequent in the type I. Based on these results, it was found that isozyme type I of the TKM 6, Cas 209 and TN 1 groups as well as isozyme type II of the DZ 192 group were composed of Intermediate and Indica types. It was also shown that Japonica type was related to the type VI of the Java 14 and TN 1 groups.

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By using image analysis, we examined the position and dimensions of white-core in the kernels of two rice cultivars for sake brewery, i.e. Hyogokitanishiki and Yamadanishiki. They were grown during the years 1992 to 1996 in Hyogo prefecture, and in 1995 and 1996 in Niigata prefecture. Standard images of white-core varied with the year and location when the kernels were obtained even for the same cultivar (Fig.1). It was suggested that the position of white-core in the kernels was stable in each cultivar irrespective of environmental conditions, whereas the dimensions of white-core fluctuated depending on the year and location where the kernels were obtained (Figs.2 and 3). These findings suggest that the position of white-core in kernels is determined genetically but that the dimensions depend on environmental factors.

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The genetic diversity of 24 Asian chestnut varieties, including 14 Japanese chestnuts (Castanea crenata) originating in Japan or the Korean Peninsula, 7 Chinese chestnuts (C. mollissima) and 3 other Castanea species, was characterized by AFLP (amplified fragment length polymorphism) using 9 primer combinations. About 60% of the amplified fragments (165/271) were polymorphic bands which were observed on both intra-species and inter-species. All varieties were identified from the differences of more than 14 bands and a lot of variety-specific AFLP fragments could be obtained. A phenogram of chestnut varieties was constructed based on polymorphisms. According to the phcnogram, all C. crenata cultivars originating in Japan were grouped into the same cluster with Shibaguri varieties which were considered the native species. In contrast, the genetic diversity of C. crenata cultivars from the Korean Peninsula was fairly extensive compared to that of C. crenata in Japan. These results suggest the possibility that cultivated chestnut in Japan might have been derived from Shibaguri or the possibility that both might have originated from the same ancestor. In addition, the genetic diversity among C. mollissima and the genetic relationship between C. crenata and C. mollissima were discussed.

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As a first step to clarify theα-amylase production in embryos, preparation of mass-isolated rice embryos was established. Morphological and biochemical characterization of the mass-isolated embryos revealed that the embryos are viable and suitable for characterization of α-amylase production. Activity staining for α-amylase revealed that the production of RAmy1A-encoded protein (isoform A) is under hormonal control, but that of other isoforms including RAmy3D-encoded protein (isoforms G and H) are not. All isoforms were repressed by glucose. The physiological role of α-amylase produced in the embryos was discussed.

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A novel chitinase was identified in a rice EST Iibrary based on a partial polypeptide sequence of a putative dormancy-related protein in rice husk and its genetic locus was detected on chromosome 4. Thereafter, the whole genomic sequence of Cht4 was determined by using TAIL-PCR based on cDNA sequence data. A full sequence of the protein encoded by Cht4 was confirmed to be significantly shorter than that of known rice chitinases, and to have a unique primary structure. The 5' flanking sequence of about 700 bp was also determined and compared with that of known chitinases. Besides a common intron in the sequence there is a polymorphism in the 3' flanking region for an inserted sequence which is similar to the Wanderer element, one of the transposons. The insertion was observed only in Indica cultivars.

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Palmitic acid is one of the two major saturated fatty acids of soybean [Glycine max (L.) Merr.] oil that is closely related with physical, chemical and nutritional qualities. The average pahuitic acid content in the seed oil of common cultivars is 11.0%. Soybean mutants with both reduced and elevated palmitic acid have been developed. Previous studies had shown that reduced palmitic acid in a mutant C1726 and elevated palmitic acid in a mutant C1727 were respectively controlled by fap1 and fap2 alleles, and reduced palmitic acid in a nrutant J3 was controlled by sop1 allele. The objective of this study is to determine the genetic relationships of sop1 allele in J3 with fap1 and fap2 alleles in C1726 and C1727, respectively. Reciprocal crosses were conducted for J3 × Bay, C1726 × Bay, J3 × C1727 and J3 × C1726. No maternal effect for palmitic acid content was observed from the analysis of reciprocal F₁ seeds in any of the crosses. The data for palmitic acid content in F₂ seeds of J3× Bay and C1726 ×Bay fitted a 1:2:1 ratio. The segregation observed from the analysis of F₂ seeds of J3 × C1727 fitted the ratio of 1:14:1 and of J3 × C1726 fitted the ratio of 3:10:3. The F₂ segregation ratio and the segregation of F₃ seeds from F₂ plants of these crosses indicated that allele for palmitic acid in J3 was at a different locus from the alleles in C1726 and C1727. The segregant with the genotype sop1sop1fap1fap1 from J3 × C1726 has an average 3.5% palmitic acid and therefore, it is considered as an important germplasm that would be an advantage for soybean oil with better physical, chemical and nutritional qualities.

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The QT2 Iine, which lacks β-conglycinin in the seed storage protein, was detected from our wild soybean germplasm collection. Although induced mutant lines lacking β-conglycinin were reported to be non viable in previous studies, the QT2 Iine grew normally and produced successive generations. To distinguish it from the non viable β-conglycinin-lacking line, this pheno-type was referred to as the “QT2-type”. In these studies, we investigated the mode of inheritance of the QT2-type and the genetic relationships between the QT2-type and some other soybean storage proteins. In spite of the fact that β-conglycinin was composed of three major subunits, genetic analysis of the QT2 Iine indicated that the QT2-type was controlled by one single dominant gene. The new genetic symbol of Scg was assigned to the QT2 type in this report. Furthermore, the mode of inheritance of the QT2-type was independent of that of the α'-subunit of β-conglycinin and seed lipoxygenases. The QT2-type hybrids, even without the presence of seed lipoxygenases, did not show any physiological abnormalities. These results indicate that the QT2 Iine is a suitable gene source to breed soybean varieties lacking β-conglycinin.

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A joint research project has been carried out between Japan and China on the origin and spread of rice in the Middle and Lower Changiiang River Valley of China by plant opal analysis since 1992. The excavation of ancient paddy fields near the Caoxieshan site in Wu County, Jiangsu Province was conducted. Ten accumulated soil layers with each cultural period property were confirmed, and the layers from the fifth layer to the tenth layer were identified as belonging to the Middle Majia-bang period (B.P.5900-6200). And the existence of paddy fields in soil layers of Chunqiu, Songze and Majiabang period were identified by plant opal analysis. Moreover, more than forty paddy field sites were excavated under the ninth or tenth layer. This paper reports on the results of quantitative and morphological analysis of plant opals on soil samples collected from nineteen paddy filed sites and ten soil layers at the Caoxieshan site in 1994 and 1995, and discusses the cultivar group and its historical change of ancient rice cultivated near the Caoxieshan site. The quantitative analysis of plant opals detected large amounts of rice plant opals from motor cell silica bodies in all the samples, suggesting that the rice cultivation near the Caoxieshan site began from the middle Majiabang period and continued up to the present. Moreover, the rapid increase of rice leaf weight inferred from plant opals in soil layers of middle Majiabang period suggested that rice cultivation had been prevalently practised during this period. The morphological analysis of plant opals suggested that the plant opals from the soil layers of middle Majiabang period were derived from japonica rice. Compared to the motor cell silica bodies from Chinese native Keng (correspond to japonica) rice, the plant opals had a larger value in b/a as well as in vertical length and lateral length, and the discriminant scores were more like those from typical japonica rice. A comparison of the discriminant scores of plant opals from the ten soil layers showed a slowly decreasing trend from the lower layers to the upper ones. And the scores were especially small for the soil layers above the third one (the Song period), suggesting that it is highly possible that the indica rice would be probably cultivated from Song period near the Caoxieshan site.

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To fully exploit the genetic potential of African rice, Oryza glaberrima Steud., we aimed at developing a series of O. glaberrima introgression lines (GILs) in the back-ground of Japonica rice (O. sativa L. cv. Taichung 65). Each GIL carrying homozygous chromosome segments from O. glaberrima will be selected using RFLP markers. As a first step, an RFLP Iinkage map based on backcross population (BC₁F₁) was constructed. QTLs for two quantitative traits, male sterility and heading date, were investigated in the BC₂F₁ population. The RFLP map contained 101 well-dispersed RFLP markers. Total map length was 1403.4 cM. Linkage arrangement of the RFLP markers was in good agreement with that of the previously constructed maps. Significant segregation distortions were observed in chromosomes 4, 5, 6 and 11. In chromosome 6, a strong distortion towards O. glaberrima was found. On chromosomes 1, 6 and 10, significant (<1%) QTLS for heading were detected. In the heterozygous condition, O. glaberrima allcles around the RFLP markers C1211 (chromosome 1) and XNpb27 (chromosome 6) delayed heading, while another O. glaberrima allele(s) around XNpb37 (chromosome 10) caused early heading. On chromosomes 3, 7 and 10, significant (< 1%) QTLS for pollen sterility were detected. O. glaberrima allele(s) in these regions reduced the pollen fertility in the heterozygous condition. On chromosome 10, a wide region showed a significant association with the trait, suggesting the existence of a powerful male-sterility gene.

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[in Japanese]

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Isoflavone contents of 15 soybean (Glycine max (L.) Merrill) cultivars were analysed using high performance liquid chromatography (HPLC). Effects of environ mental and genetic factors on isoflavone contents were evaluated by analysing the seeds produced in three sowing dates in two locations (Londrina - 23°11'50” S latitude and Ponta Grossa - 25° 05'58” S Iatitude), of Parana state, Brazil. Cultivars IAC 100, IAS 5, IAC 8, GO/BR-33 and BR-37 showed the highest levels of total isoflavones (ranging from 146.9 to 119.5 mg/100g), while cultivars BA/BR-31 and BR-36 showed the lowest levels (57.5 and 53.7 mg/IOOg, respectively), in both locations. Average total isoflavone concentration in Londrina was 31% Iower than in Ponta Grossa (82.0 mg/100g and 119.7 mg/IOOg, repectively), probably as a consequence of local temperature (23°C, and 20°C, respectively), and other environmental differences such as soil.

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A new glutmous upland nce vanety “Yumenohata mochi” with medium maturationtime, which was registered in Ministry of Agriculture, Forestry and Fishery as “upland rice Norin mochi 60”, was released in 1996 by Plant-Biotechnology lnstitute, Ibaraki Agricultural Center. This variety was developed after two backcrossings with the improved variety `upland rice Norin mochi 4'(NG4) in a cross between NG4 and the native Indian variety `Jaypole Collection N0.81'(JC81) selected as a drought resistant parent by the investigation of root amount and thickness. The selection of drought resistant lines was conducted on the basis of rootamount and thickness as well as shoot traits. Yumenohatamochi showed high drought resistance in upland fields of Japan. The eating quality was equivalentto that of paddy glutinous rice varieties with middle level of eating quality. Among the upland rice varieties, this variety is considered to display the highest eating quality at present. Thus, Yumenohatamochi is expected to contribute to the stable production of upland rice in Japan and to the increaseof the demand for upland rice.

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