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POSTERS: Population biology and genetics

Competition between R. solanacearum sequevars causing Moko disease on banana (Musa acuminata) in Suriname
Crystal Conner - University of Florida MREC. Ana Maria Bocsanczy- University of Florida MREC, Brantlee Spakes Richter- University of Florida, David Norman- University of Florida MREC

Ralstonia solanacearum is the causal agent of Moko/Bugtok disease. Musa acuminata, Cavendish cultivar, accounts for 47 percent of global banana production and is susceptible to R. solanacearum. Our objective was to characterize isolates of R. solanacearum from Cavendish bananas collected in Suriname, August 2018. Sequencing of the endoglucanase gene identified sequevars 4 (P856) and 38 (P853). Previously, sequevar 4 had been associated with banana but sequevar 38 had not. Competition assays were performed in vitro and on banana with strains P853 and P856, using Rifampicin mutants of each strain. For in vitro assays, P853, P856, P853R, and P856R were grown in liquid CPG/ CPGR for 24 h and diluted to 106 cells/ml. Mixtures (1:1) were created with P853R/P856, and P856R/P853. Suspensions were dilution plated on CPG/ CPGR, incubated for 24 hours, and colonies were counted. Six plants were inoculated with each isolate or mixture by stem injection with 1 ?l of a 1x106 cell/ml bacterial suspension. Plants were maintained in a greenhouse with controlled temperature and lighting. After three weeks, 100 ?l of sap was extracted from each plant, suspended in 1.9 ml of liquid CPG/ CPGR, dilution plated onto CPG/ CPGR agar, and counted after 24h. In two repetitions in vitro, P856 outcompeted P853; however the reverse was observed in an initial repetition of the in planta assay. Additional repetitions are in progress, as are host range assays with both strains on Solanaceae species and squash. Preliminary tests reveal susceptibility to strain P853 on Solanaceae and Cucurbitaceae species.