Diploid potato breeding populations with quantitatively inherited traits related to pest resistance were selected. These lines were further crossed to 4x cultivars via FDR 2n pollen to examine the level of transmission of variable traits including the resistance to bacterial wilt (BW), potato tuber moth (PTM), and root-knot nematodes (RKN). Transmission of quantitative traits including late blight (LB) resistance and the presence of glandular trichomes which confer general insect resistance in tetraploid genotypes was also examined in the 4x × 2x progeny. All the quantitative traits except for the resistance to PTM were transmitted to progeny with a high frequency of resistant progenies. Among 557 clones from 4x × 2x crosses, 114 clones showed a combination of two types of quantitative resistance traits in a single clone. Four types of cornbinations, BW + RKN (85 clones), LB + BW (14 clones), BW + glandular trichonres (1 clone), and RKN + glandular trichomes (14 clones), were identified. Our results indicated that: 1) the transmission of combined quantitative traits related to pest resistance was possible via FDR 2n pollen; and 2) quantitative traits related to LB resistance and the presence of glandular trichomes could be transmitted to progeny with a high frequency.

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Survival and yield performance of the diploid potato genotypes selected during field trials in the coastal desert area of Lima, Peru, were evaluated under sub-tropical conditions in San Ramon, Peru, in a field with severe bacterial wilt (BW) infestation. Some selected diploid genotypes, which had been found to be resistant also to other biotic stresses in field trials in Lima, showed comparable yields to those of the tetraploid standard local cultivars under the subtropical conditions. Based on analysis of variance, the effects of the resistance to BW on the survival and yield were not consistent. These facts were considered to result from interactions between the BW resistance, adaptation (e. g. heat tolerance) and environmental factors. Observations of the latent infection provided an insight into how the expression of BW resistance is modified by environmental and pathogenic factors under field conditions.

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Protein Z, a major water-soluble seed protein of barley, is thought to be one of the factors influencing foam stability of beer. To find the breeding material for raising the protein Z content in nralting barley, we surveyed the protein Z contents of malting barley varieties. Generally, North American six-row varieties had higher contents than Japanese varieties. Especially, variety Bonanza had the highest protein Z content among the 62 varieties surveyed. Using the lines derived from the crosses between Bonanza and the Japanese malting varieties, we found that the protein Z structural gene region contributed to the protein Z content of seeds. We also estimated the position of protein Z structural gene on chromosome 4H using a set of RFLP markers. Consequently, we concluded that the high protein Z content of Bonanza could be introduced and screened by the RFLP patterns of the protein Z structural gene.

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We carried out quantitative trait loci (QTL) analysis for three years to identify genes controlling the nulnber of vascular bundles (Vb) in the peduncle and primary rachis branch (Rb) in rice (Oryza sativa L.). Sixty-five reconrbinant inbred lines derived from the cross between ajaponica variety Asominori and an indica variety IR24 were used for QTL mapping and 289 markers were employed to identify QTLs. Nine QTLs for Vb were detected on chromosomes 1 (two regions), 4, 5(two regions), 6 (two regions), 11 and 12. One of the QTLs on chromosome 6 was detected in all 3 tested years. Three QTLs on chromosomes 1, 4 and 12 were identified in 2 years. Most effective QTLs were found on chromosomes 4 and 6, explaining 20-23% of the total variance. The alleles of IR24 increased Vb except for QTL on chromosome 4. One of the 9 QTLs for Vb was located close to the region established as QTLs for the number of spikelet and grain. For the number of Rb, three QTLs on chromosomes 2 and 8 (2 of 4 regions) were commonly detected in all 3 tested years and five others on chromosomes 4, 6 and 8 were found in at least one year. The QTL on chromosome 8 was the most effective and explained 18-25% of the total variance. Except for QTL on chromosome 6, the alleles of Asominori increased Rb. The expression of QTLS was more stable in Rb than in Vb. The QTLs for Vb and Rb and gene loci of diagnostic traits for the differentiation between indica and japonica types are discussed.

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We previously identiffed three random amplified polymorphic DNA (RAPD) markers linked to a major gene conferring clubroot resistance (CR) in Brassica rapa. The markers were cloned and sequenced. A pair of primers were designed for specific amplification of each marker. All three CR markers were specifically amplified as clear single and dominant bands. Identity of the loci of the amplified markers with the original RAPD markers was demonstrated using a segregating F₂ population. The marker bands can be amplified by at least two types of PCR machine. Therefore these three markers may be widely used as a reference to CR genes in the genome of B. rapa. Presence of the markers in turnips and Chinese cabbage cultivars was examined. Turnips showed a high degree of DNA polymorphism within cultivars. No relationship between CR and the presence of the marker bands was detected, while Chinese cabbage hybrid cultivars showed a rather low DNA polymorphism. One of the CR markers, RA12-75A was found to be useful for the breeding of CR Chinese cabbage, because no clubroot-susceptible cultivars of Chinese cabbage harbour this marker band. Use of these specifically amplified markers in marker-as-sisted selection (MAS) of Brassica crops is discussed.

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In order to apply isozymes as genetic markers tn sugarcane breeding, the polymorphism of 24 Japanese varieties, including breeding nraterials, was analyzed using 12 enzyme systems. Of the enzymes examined, the activity of Alcohol dehydrogenase (ADH), Esterase (EST), Glutanrate oxaloacetate transaminase (GOT), Isocitric dehydrogenase (IDH) and Peroxidase (POX) was clearly revealed and polymorphism was detected among the varieties. The 24 varieties could be identified by these five enzyme systems. In the selfed progenies of NiF8, Ni9 and RK86-129, Iarge numbers of bands in EST and POX were segregated. Segregation patterns in some of the isozymes in EST and POX showed a monogenic segregation ratio of 3 : 1. However, others deviated from the monogenic segregation ratio. In a parentage test using isozymes, the hybridity of alnrost all the seedlings could be identified in 10 cross combinations. These results indicate that the isozyme technique is a useful tool for variety identification and progeny hybridity in sugarcane breeding.

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A major protein endogenously expressed in Camellia pistils with a high level of expression at the period of anthesis was detected by two-dimensional gel electrophoresis. Their N-terminal amino acid sequences showed a high level of honrology with pathogenesis-related (PR)-1 proteins from plants. Northern blot analysis demonstrated that the protein was expressed specifically in pistils. The gene coding the PR-1-Iike protein was cloned from tea (Camellia sinensis), and compared with those of other PR-1 and PR-1-Iike proteins. Based on sequence homology and induction, the protein was designated as Camellia PR-1-Iike (PRL-1) protein. The deduced PRL-1 protein sequence displayed the highest homology with STS14, which was earlier described as a PR-1-Iike protein expressed in pistils of potato. With the addition of this PRL-1 protein, we discussed the possibility of a new class of PR-1-Iike proteins, which are specifically induced in pistils of many plaut families. The sequence of PRL-1 gene is registered as Accession: AB015047.

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Mapping of quantitative trait loci (QTLs) in plants was performed using the data of marker genotypes and phenotypic values of a quantitative trait in a segregating generation such as F₂ and BC1 derived from the crossing of two pure lines. A Iarge sample must be examined to map QTLs with small effects. However genotyping of many markers for a large number of individuals is costly. For mapping QTLs using a F₂ population, useful information is included in the derived F₃ Iines. Phenotypic measurements of F₃ Iines can be obtained at a relatively low cost. Therefore, by utilizing tlhe phenotypic measurements of F₃ in addition to F₂ data, the detection of QTLs could be improved even when only a small number of F₂ individuals are genotyped. In this paper a model for mapping QTLs is proposed, where the data of both F₂ mdividuals and F₃ Iines are jointly analyzed. The effectiveness of this method is evaluated theoretically and numerically and it is shown that the ability of detecting QTL can be remarkably enhanced, especially when the heritability of the trait is low.

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DNA markers linked to a fertility restorer (Rf) gene for Ogura cytoplasmic nrale sterility in radish (Raphanus sativus L.) were screened by bulked segregant analysis using random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) and high-resolution agarose gel electrophoresis. Ten male-fertile and 10 male-sterile plants arbitrarily selected from the F₂ segregating population made by the selfing of an F₁ plant between ‘MS-Gensuke' (a male-sterile line possessing Ogura cytoplasm) and ‘Comet' (a restorer having a nuclear Rf gene), were used as the materials for bulked DNA samples. Using 10 out of 260 arbitrary prixners tested, RAPD fragments specific to the bulked DNA samples from male-fertile F₂ plants were identified. Further Itnkage analysis performed with 89 individuals in the F₂ segregating population showed that the seven RAPD markers were linked to the Rf gene. RAPD markers distributed on both sides of the Rf gene, and the closest marker, OPH11₄₁₀ positioned 1.2 cM from the Rf gene. The three closest RAPD markers to the Rf gene were converted to SCAR markers by molecular cloning and nucleotide sequencing. This allowed identification of more reliable DNA markers linked to the Rf gene than the RAPD fragments.

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Root thickness was evaluated in the diploid species, Ipomoea trifida. Variation in root thickness was observed among the accessions and some of them produced thick roots >15 mm in diameter. One clone from an Indonesian I. trifida population had storage root like root formation, however, dry matter content was much lower than that of sweetpotato. Most of the progenies of the cross between sweetpotato and diploid accessions of I. trifida produced storage roots. The highest storage root obtained was 1, 800 g/plant. High storage root weight was also found in back crossed progeny of the hybrids to sweetpotato but dry matter content was low. Therefore, diploids with thick roots are considered to have a high potential for storage root formation. In order to develop cultivars with high storage root yield and high dry matter content, improvement of dry matter content of diploids and/or use of high dry matter content sweetpotato may be required. Diploid I. trifida with thick roots or storage root-Iike roots will be useful not only for development of new cultivars with high storage root yield but also for studying phylogeny of sweetpotato.

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