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This study was carried out to utilize DNA markers in carnation (Dianthus caryophyllus L.) breeding and to clarify the genetic basis such as the ploidy level and genetic diversity of carnation cultivars. 1. Construction of genetic linkage map, quantitative trait locus (QTL) analysis and application to breeding in carnation To improve the selection efficiency in carnation breeding for resistance to bacterial wilt caused by Burkholderia caryophylli, the first genetic linkage map for the carnation was constructed by using a resistance-segregating population of 134 progeny lines derived from a cross between 'Carnation Nou No.1' (a line resistant to bacterial wilt) and 'Pretty Favvare' (a susceptible cultivar) based on RAPD and SSR analysis. The linkage map contained 137 RAPD and 9 SSR markers. Linkage analysis revealed that 124 loci could be mapped to 16 linkage groups that extended for 605.0 cM. The average interval between two loci was 4.9 cM. QTL analysis was applied to replication 8 evaluations of resistance to bacterial wilt. A QTL with a large resistance effect was detected on Group 6, which accounted for 60.5% of the total phenotypic variance with an LOD score of 23.46. Two other QTL with a small effect were detected on Groups 2 and 5 with LOD scores of 2.32 and 2.87, respectively. These results suggest that resistance to bacterial wilt in carnation is related to one major and at least two minor genes. The availability of marker-assisted selection (MAS) using DNA markers close to the QTL of resistance to bacterial wilt in carnation was examined. The STS-WG44 marker tightly linked to the major resistance gene was detected in all backcross lines with resistance selected by the root-soaking method. The ratio of markers OQ12 and STS-WB66 close to the two QTL with a small effect in resistant lines was lower in succeeding generations of backcrossing. These findings suggest that STS-WG44 is available for selecting resistant lines. In practical breeding populations, the difference in mean disease incidence between two groups categorized as having or lacking STS-WG44 was 62.6% and STS-WG44 was present in most lines showing disease incidence of less than 20%. These findings suggest that STS-WG44 as a selective marker facilitated the narrowing of populations to those that are highly resistant for practical breeding. MAS would be available for breeding improved resistance to bacterial wilt in carnation. Flower color is an important trait in ornamental plants. To understand the genetic basis for anthocyanin pigmentation traits in the flower petals of carnation, the segregation of anthocyanin content in petals was evaluated and QTL analysis was conducted by using the linkage map constructed in this study. The frequency of low anthocyanin content (

To contribute to the development of new integrated practices for the control of soilborne diseases, the relation between the development of bacterial wilt, a serious soilborne disease induced by Ralstonia solanacearum, and calcium (Ca) nutrition in tomato (Lycopersicon esculentum Mill.) seedlings was investigated. Increased application of Ca in the soil or increased Ca concentrations in the nutrient solution reduced the disease severity in the seedlings of resistant cultivars, and decreased the populations of the pathogen in stems. This Ca-dependent resistance was also observed in susceptible tomato seedlings grafted onto rootstocks of a highly resistant cultivar, and in various resistant cultivars. The resistance was affected by the Ca concentration after infection with the pathogen, but not before infection, suggesting that the Ca concentration in plant tissues after infection might regulate the expression of the resistance. When varietal differences in the resistance and nutrient uptake by the seedlings were examined, highly resistant cultivars were characterized by a high Ca uptake. This characteristic of high Ca uptake in the cultivars was due to differences in the Ca uptake of the roots, based on the results of experiments using mutually grafted seedlings of cultivars differing in resistance. Fertigation of solutions containing high concentrations of Ca was effective on the suppression of the disease. Moreover, application of composts with various Ca concentrations reduced the disease severity, and the degree of reduction was correlated with the increase of the Ca uptake in shoots. These results may contribute to the new integrated practices for the control of bacterial wilt in tomatoes.

'Daizaburou' is a new rootstock cultivar of eggplant,and was registered as 'Nasu Nourin Dai No.3' in 2003. 'Daizaburou' is an eggplant (Solanum melongena) and an inbred line, though most of the rootstock cultivars for eggplant are interspecific hybrids or related species in Japan. 'Daizaburou' is highly resistant to bacterial wilt and Fusarium wilt. The earliness and uniformity of seed germination and early growth of 'Daizaburou' seedlings were superior to those of related species rootstock varieties, this means that grafting is easy. The total yield of scions grafted on 'Daizaburou' were equal to those of 'Daitaro'. The fruit qualities such as shape or outer color, of scions on 'Daizaburou' were almost the same as those on 'Daitaro'. 'Daizaburou' is suitable for summer culture in areas infested with bacterial wilt.

'Tomato Chuukanbohon Nou 9', synonym of 'Tomato Parental Line 9', with a high level of bacterial wilt resistance and a larger fruit size was developed. The level of resistance to bacterial wilt of the line was clearly higher than those of the leading varieties for fresh market and of the rootstock, 'Kagemusha'. Compared with the highly resistant cultivar 'Hawaii7998', the resistance was identical or slightly lower. The resistance to bacterial wilt may be controlled by a small number of genes with major effect. In addition, no association of bacterial wilt resistance with the fruit size, color and shape was observed. The fruit of 'Tomato Chuukanbohon Nou 9' is slightly flattened round, pink in outer color and the commercial size averages 160 to 200g. The cultivar is very promising as a breeding material for fresh-market variety with bacterial wilt resistance.

Bacterial wilt (Burkholderia caryophylli) is one of the most important and damaging diseases of carnations (Dianthus caryophyllus) in Japan. Interspecific hybridization between carnation and D. capitatus ssp. andrzejowskianus, a highly resistant wild species to bacterial wilt, was carried out in order to introduce the resistance into carnation cultivars. Thus, a new bacterial wilt resistant line 'Carnation Nou No.1' was selected out of the F_1 progenies. Two approaches were used to improve the vase life of carnations. The application of α-aminoisobutyric acid (AIB) in continuous treatment and pretreatment was effective in the preservation of the freshness of cut carnation flowers. Moreover, conventional cross-breeding techniques were used to develop many carnation lines with long vase life. Many lines with long vase life that show low ethylene production or low ethylene sensitivity were obtained.

To suppress bacterial wilt of tomato caused by Ralstonia solanacearum with soil administration, soil conditions that influence the production of extracellular polysaccharides (EPS) in R. solanacearum were surveyed, and the prevention of this disease by strains that do not produce EPS (EPS- strains) was investigated. The culture conditions, using either liquid medium or sterilized soil were investigated to induce the phenotype conversion (PC) in relation to the reduction or loss of EPS production in R. solanacearum. EPS- colonies were frequently detected under unfavorable culture conditions, such the use of a rather alkaline medium (pH8 and pH8.5), higher temperature (37℃) or still culture rather than shaking culture. The culture conditions under which the EPS- colonies were detected with a high frequency varied depending on the strains tested. In the case of culture conditions of the bacterium using either sterilized of non-sterilized soil, EPS- colonies were also observed with a high frequency in all the cases, including, acidic soil, higher temperature, and soil moisture exceeding the maximum water holding capacity. Disease severity was evaluated after the EPS-producing strains were inoculated either alone or simultaneously with EPS-non-producing strains by mixing into soil where subsequently tomato was planted. When EPS-producing strains and EPS-non-producing strains were simultaneously inoculated, the damage was less serious than in the case of inoculation with EPS-producing strains alone. When the ratio of EPS-non-producing cells to EPS-producing cells increased, the effect on disease suppression was more pronounced. If the phenotype conversion of R. solanacearum living in soil could be induced with a high frequency by soil administration, bacterial wilt disease may be effectively suppressed.

本試験では養液栽培において,青枯病の発病抑制効果が期待できるスイートバジル,オレガノ,ローマンカモミールを用いて,ハーブの栽植密度を変えてトマトとの混植試験を行い,ハーブの混植が青枯病発病ならびに培養液中の青枯病菌密度に及ぼす影響を調査した。その結果,対照区と比べて,スイートバジル混植区では青枯病発病が4日遅れ,オレガノ,ローマンカモミール混植区では,青枯病の進行が508日抑制された。さらに,スイートバジル,オレガノ混植区では培養液中の青枯病菌密度が検出限界以下(約10^2 cfu/mL以下)に減少した。以上のことから,ハーブの混植により,青枯病発病抑制,青枯病進行抑制,培養液内の青枯病菌密度低下効果などが得られる可能性が示唆された。, The effect of the mixed planting of herbs and tomatoes at different planting density on the incidence of bacterial wilt of tomatoes was investigated in hydroponics. The herbs used in this study were sweet basil, oregano and roman chamomile, all of which are known to have antibacterial activities against Ralstonia solanacearum. The mixed planting with sweet basil delayed the incidence of bacterial wilt disease by four days compared with the control treatment, while the mixed planting with oregano and roman chamomile delayed the development of bacterial wilt disease in tomato plants by five to eight days. Furthermore, the mixed planting with sweet basil and oregano reduced the population density of Ralstonia solanacearum to less than 10^2 cfu/mL in nutrient solutions. These results suggested the effectiveness of mixed planting of herbs and tomatoes for the avoidance of severe damage by bacterial wilt disease.