Quantifying Host Range in the Ralstonia solanacearum IIB-4 Clade
Date
2022-03-08
Authors
Beutler, Jonathan
Lowe-Power, Tiffany
Norman, David
Georgoulis, Stratton
William, Darrielle
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
Type
Conference Presentation
Degree Level
Abstract
Bacterial wilt diseases caused by Ralstonia solanacearum are major crop production constraints of significant global concern. Ralstonia are diverse plant pathogenic bacteria with thousands of distinct lineages in four phylogenetic branches (phylotypes) of continental or archipelagic origins in Africa, Asia, the Americas, and the South Pacific. The Ralstonia pathogen family has a remarkably broad host range, infecting hundreds of host species in dozens of taxonomic families, but the breadth of host range is not uniform amongst the thousands of known strains. The phylotype IIB, sequevar 4 (IIB-4) clade exhibits a particularly broad host range and has caused multiple economically important wilt outbreaks in the Americas. Here we quantified virulence and a snapshot of the IIB-4 host range using 19 non-clonal strains isolated in Florida, the Caribbean, and Latin America- a broad swath of the phylotype II ancestral range. We monitored disease progress from stem and soil-drench inoculations on four experimental hosts: tomato (Solanum lycopersicum cv Moneymaker), melon (Cucumis melo cv. Sweet Granite), Impatiens (Impatiens walleriana cv. Beacon Orange), and banana (Musa acuminata cv. Dwarf Cavendish). We calculated area under disease progress curve (AUDPC) values individually for each of the 3,005 plants in the study and aggregately for each host-strain combination. Tomato plants were the most broadly susceptible: 17 strains were highly virulent, and two strains were moderately virulent. Virulence on melon plants was more variable: eleven strains were highly virulent, four strains were moderately virulent, and four strains exhibited low virulence. Virulence on Impatiens plants was also variable: twelve strains were highly virulent, four strains were moderately virulent, and three strains exhibited low virulence. Banana plants were the most broadly resistant: one strain was highly virulent, two stra ins were moderately virulent, five strains exhibited low virulence, and eleven strains were avirulent. Through concurrent phylogenetic analysis of 49 conserved Ralstonia genes, we demonstrate that closely related IIB-4 strains can exhibit considerable variation in virulence and pathogenicity on diverse hosts. Such variation points to favorable targets for further genetic screening to investigate the determinants of host-specificity traits.
Description
Keywords
Wilt, Ralstonia, Host Specificity
Citation
Degree
Department
Program
Advisor
Committee
Part Of
Soils and Crops Workshop