Evaluation of tomato, eggplant and pepper accessions for resistance to Ralstonia solanacearum species complex (RSSC) strains from Louisiana

Abstract

Bacterial wilt (BW), caused by Ralstonia solanacearum species complex (RSSC), is a major disease affecting tomato and other solanaceous crops produced in Louisiana and worldwide. The most effective and economic management strategy for BW is the use of crop genetic resistance. However, regional genetic variation among RSSC strains has made stable and durable resistance elusive. A collection of tomato, eggplant and pepper (TEP) accessions that responds to globally diverse strains in the RSSC was screened for resistance to six RSSC strains, belonging to phylotypes I and II, from Louisiana, United States (US). Wilt severity was quantified from six days up to 25 days post-inoculation (DPI). Wilting increased most rapidly to 10 DPI and was generally more severe with Phylotype II strains. However, wilt response profiles depended on the accession-strain combination. Differences in aggressiveness, as measured by the area under the disease progress stairs, were observed among the phylotype I and II strains on TEP. Wilting responses were the most severe with the tomato accessions. Hawaii 7996, TML46, CLN1463 and R3034 were highly resistant to all phylotype I strains, but Hawaii 7996 displayed the best resistance to phylotype II strains. Remarkably, eggplant accession Ceylan SM 164 was resistant to all six strains. Eggplant accessions SM6, Surya, and AG91–25, as well as pepper accessions CA8 and MC4, were moderately to highly resistant to all six strains. Although resistance spectrum and levels of these tomato, eggplant and pepper accessions need to be confirmed by further experiments, our results already indicate that these accessions are potential BW-resistant rootstock candidates for grafting to susceptible market-driven tomato, eggplant and pepper produced in this US state.