Assessing host specialization ofBotrytis cinereaon lettuce and tomato by genotypic and phenotypic characterization

Abstract

This study tested the hypothesis that Botyrtis cinerea shows host specialization on tomato and lettuce, using phenotypic and genotypic tools. Strains were isolated from tomato and lettuce grown together in the same greenhouse. Forty‐four lettuce strains and 42 tomato strains were investigated for their genetic diversity and their aggressiveness. Both gene diversity and allelic richness were significantly higher in lettuce strains than in tomato strains (P = 0·01). Cluster analysis revealed a clear division of the strains under study into two clusters. However, this structure did not separate the strains according to their host of origin. Tomato strains were significantly more aggressive than lettuce strains when inoculated on tomatoes (P = 0·001), but no significant differences in aggressiveness were observed when the strains were inoculated on lettuce (P = 0·17) or on apple (P = 0·87). The results suggest an absence of clear host specialization of B. cinerea on tomato and lettuce.

The polyphagous plant pathogenic fungusBotrytis cinereaencompasses host‐specialized and generalist populations

“…A pattern of pathogenicity partially consistent with specialization was previously observed in indoor samples of B . cinerea collected on lettuce and tomato but differences in pathogenicity were not associated with population subdivision (Leyronas et al ., ). To the best of our knowledge, this is the first report of host‐associated ecological divergence in B .…”

“…For example, Leyronas et al . () showed lack of genetic differentiation between B . cinerea populations found on tomato ( Solanum lycopersicum ) and lettuce ( Lactuca sativa ).…”

“…g . Karchani‐Balma et al ., ; Leyronas et al ., ) host plants revealed differentiation between sympatric populations from different hosts. However, no correlation was found between population structure and cross‐pathogenicity, suggesting that the observed differentiation between populations was not related to host specialization, or that it was instead linked to components of specialization that have not been measured.…”

“…However, no correlation was found between population structure and cross-pathogenicity, suggesting that the observed differentiation between populations was not related to host specialization, or that it was instead linked to components of specialization that have not been measured. For example, Leyronas et al (2015) showed lack of genetic differentiation between B. cinerea populations found on tomato (Solanum lycopersicum) and lettuce (Lactuca sativa). Patterns of pathogenicity were also consistent with generalism, as strains showed significant differences in quantitative pathogenicity on tomato hosts, but not on lettuce.…”

First report of Sclerotinia subarctica in France detected with a rapid PCR-based test

“…Leaves of witloof chicory were inoculated with isolate SS_2428, following a method routinely used in our laboratory for pathogenicity tests with B. cinerea (Leyronas et al 2015).…”