1. Bacterial Wilt Disease Occurrence on Eggplant Rootstock (EG203) Grafted Tomatoes in Ralstonia solanacearum Infested Soil Munhaeng Lee 1*, Heekeng Lee 1, Hong Gi Kim 2, Hyeong Jin Jee 3, Yong Ki Kim 3, Chang Ki Shim 3, Jeong Soon Kim 3, and Youn Su Lee 4* Buyeo Tomato Experiment Station, CARES Buyeo 323-814, Korea 1, Department of Applied Biology, Chungnam National University, Daejeon 305-764, Korea 2, National Academy of Agricultural Science Department of Agro-food Safety, Organic Agriculture Division 3, Department of Applied Plant Science, Kangwon National University, Chuncheon 200-701, Korea 4 Bacterial wilt resistant eggplant rootstock EG203 significantly reduced bacterial wilt incidence in field experiments. Compared to commercial root stocks Chung- gang and B-blocking, eggplant rootstock EG203 showed a stable resistance against bacterial wilt disease of tomato caused by Ralstonia solanacearum. In the field experiment in 2009, non-grafted Yoyo seedlings showed 20~80% disease incidence compared to the EG203 grated tomato seedlings showed 2 ∼ 5% disease incidence. In the field experiment in 2010, eggplant rootstock EG203 grated tomato seedlings showed 0% disease incidence. On the other hand, commercial root stocks Chung-gang and B-blocking showed 0 ∼ 0.2% and 0 ∼ 0.1% disease incidence, respectively, and Yoyo showed 12% disease incidence. Number of fruits per plant of eggplant rootstock EG203 grated tomato was significantly different compared to those of commercial root stock (Chung-gang or B-blocking) grafted tomatoes. Eggplant root stock EG203 grafted toamto had an average 101 ∼ 115 fruits per plant. Commercial root stocks Chengang and B-blocking grafted tomato had an average 121 ∼ 130 fruits per plant. In the field experiment in 2011, EG203 root stock grafted tomato Yoyo exhibited 0 ∼ 1% disease incidence, and commercial root stock Chung-gang grafted tomato showed 60 ∼ 85% disease incidence. Based on these results, when the conditions are favourable for the occurrence of bacterial wilt disease, eggplant root stock EG203 showed strong resistance against R. solanncearum. Further studies on the mechanisms involved are necessary. Materials & Methods Results & Discussion Abstract References The experiment was carried out by using tomato variety Yoyo(Dakki) and tomato rootstocks B-blocking(Dakki) and Chunggang(Monsanto), as well as one eggplant rootstock EG203(Buyeo Tomato Experiment Station) against wilt disease caused by Ralstonia solanacearum in the field. Tomato rootstock B- blocking which shows strong resistance against bacterial wilt has been widely used(Han et al.,2009). Tomato rootstock Chunggang was developed in 2008. Eggplant rootstock EG203 was introduced from AVRDC. Eggplant rootstock EG203 was seeded three weeks before the seeding of tomato Yoyo. Tomato rootstock Chunggang was seeded when the Yoyo was seeded. Three weeks after the seeding, seedling were grafted and the grafted seedlings were cultured for 1 week in rootage room. The experiments were carried out in the field at Gumi, Gyeongsangbuk-do, Korea from 2009 to 2011. Each year, plants were transplanted to the field during June, and the results were analyzed in August. Disease incidence of bacterial wilt on grafted and non-grafted tomatoes at Gumi were evaluated in 2009, 2010 and 2011. Bacterial wilt resistant eggplant rootstock EG203 significantly reduced bacterial wilt incidence in field experiments. Compared to commercial root stocks Chung-gang and B-blocking, eggplant rootstock EG203 showed a stable resistance against bacterial wilt disease of tomato caused by Ralstonia solanacearum. In the field experiment in 2009, non-grafted Yoyo seedlings showed 20~80% disease incidence compared to the EG203 grated tomato seedlings showed 2 ∼ 5% disease incidence. In the field experiment in 2010, eggplant rootstock EG203 grated tomato seedlings showed 0% disease incidence. On the other hand, commercial root stocks Chung-gang and B- blocking showed 0 ∼ 0.2% and 0 ∼ 0.1% disease incidence, respectively, and Yoyo showed 12% disease incidence. Number of fruits per plant of eggplant rootstock EG203 grated tomato was significantly different compared to those of commercial root stock (Chung-gang or B-blocking) grafted tomatoes. Eggplant root stock EG203 grafted toamto had an average 101 ∼ 115 fruits per plant. Commercial root stocks Chengang and B-blocking grafted tomato had an average 121 ∼ 130 fruits per plant. In the field experiment in 2011, EG203 root stock grafted tomato Yoyo exhibited 0 ∼ 1% disease incidence, and commercial root stock Chung-gang grafted tomato showed 60 ∼ 85% disease incidence. Based on these results, when the conditions are favourable for the occurrence of bacterial wilt disease, eggplant root stock EG203 showed strong resistance against R. solanncearum. Further studies on the mechanisms involved are necessary. a The results are the average of three replications in each farm. In each farm, each replicate consisted of 100 plants. Table 1. Disease incidence of bacterial wilt on grafted and non-grafted tomatoes at Gumi in 2009 a Table 2. Disease incidence and various characteristics of growth and development of grafted and non-grafted tomatoes at Gumi in 2010 a a The results are the average of three replications in each farm. In each farm, each replicate consisted of 100 plants. Fig 1. Comparison of bacterial wilt symptoms on tomatoes grafted with tomato rootstock Chunggang and eggplant rootstock EG203. Aganon Clarita P., Mateo Lun G., Cacho Dennis, Anacleto Bala Jr and Aganon Teotimo M. 2002. Enhancing off-season production through grafted tomato technology. Philippine Journal of crop science 27(2) 3-9 Frey, P., Prior, P., Marie, C., Kotouiansky, A., Trigaliet-Demery, D. and Trigalet, A. 1994. Hrp mutants of Pseudomonas solanacearum as potential biocontrol agents of tomato bacterial wilt. Appl. Environ. Microbiol. 60:3175-3181 Guo, J., Qi, H., Guo, Y., Ge, H., Gong, L., Zhang, L. and Sun, P. 2004. Biocontrol of tomato wilt by plant growth- prpmoting rhizobacteria. Biol. Control 29:66-72 Hayward, A. C. 1991. Biology and epidemiology of bacterial wilt caused by Pseudomonas solanacearum. Annu. Rev. Phytopathol. 29:65-87 Han Youkyoung, Min Jisen, Park Jonghan, Kim daehyun, Lee Jungsup and Kim Hyeonghwan. 2009 Screeng of tomato cultivars resistance to bacterial wilts. Res. plant disease 15(3): 198-201 Lin Chihhung, Hsu Shihtien, Tzeng Kuoching, Wang Jawfen. 2008. Application of a preliminary screen to select locally adapted resistant rootstock and soil amendment for integreated management of tomato Bacterial wilt in Taiwan. Plant disease 92: 909-916 Palade M. C. and Wu D. L. 2005. Increasing off-season tomato production using grafing technology for peri-urban agricultural in southeast Asia. ISHS Acta Horticulturae 742: International conference and Exhibition on soilless culture: ICESC Trigalet, A., Trigalet-Demery, D. and Prior, P. 1998. Elements of biocontrol of tomato bacterial wilt In: Bacterial wilt diseased. by Prior, P., Allen, C., Elphinstone, J., pp332-336. Springer, Berlin a The results are the average of three replications in each farm. In each farm, each replicate consisted of 100 plants. Table 3. Disease incidence of bacterial wilt on grafted tomatoes at Gumi in 2011 a