Diversity and distribution of Ralstonia solanacearum strains in Guatemala and rare occurrence of tomato fruit infection

Fifty-nine Ralstonia solanacearum isolates from diverse crops and regions were collected and characterized to determine the distribution and diversity of this soilborne pathogen in Guatemala. Three distinct types were present: a phylotype I, sequevar 14 strain, probably originating from Asia, infecting tomatoes and aubergines at moderate elevations; a phylotype II, sequevar 6 strain of American origin causing Moko disease in lowland banana plantations; and a phylotype II, sequevar 1 (race 3 biovar 2) strain causing brown rot on potatoes, Southern wilt of Pelargonium spp. and bacterial wilt of greenhouse tomatoes at high elevations. These data on strain diversity will inform effective regional efforts to breed for wilt resistance. A sensitive enrichment method did not detect the pathogen in fruits from naturally infected commercial tomato plants in Guatemalan fields and greenhouses, although it was detected in 6% of fruits from a wilt-resistant hybrid. Low numbers of R. solanacearum cells were also infrequently detected in fruits from plants artificially inoculated in the growth chamber with either race 3 biovar 2 or a phylotype II tomato strain.