Botrytis pseudocinerea, a New Cryptic Species Causing Gray Mold in French Vineyards in Sympatry withBotrytis cinerea

Abstract

Botrytis cinerea is a major crop pathogen infesting >220 hosts worldwide. A cryptic species has been identified in some French populations but the new species, B. pseudocinerea, has not been fully delimited and established. The aim of this study was to distinguish between the two species, using phylogenetic, biological, morphological, and ecological criteria. Multiple gene genealogies confirmed that the two species belonged to different, well-supported phylogenetic clades. None of the morphological criteria tested (spore size, germination rate, or mycelial growth) was able to discriminate between these two species. Sexual crosses between individuals from the same species and different species were carried out. Only crosses between individuals from the same species were successful. Moreover, population genetics analysis revealed a high level of diversity within each species and a lack of gene flow between them. Finally, a population survey over time showed that B. cinerea was the predominant species but that B. pseudocinerea was more abundant in spring, on floral debris. This observation could not be explained by temperature adaptation in tests carried out in vitro or by aggressiveness on tomato or bean leaves. This study clearly establishes that B. cinerea and B. pseudocinerea constitute a complex of two cryptic species living in sympatry on several hosts, including grapevine and blackberry. We propose several biological or molecular tools for unambiguous differentiation between the two species. B. pseudocinerea probably makes a negligible contribution to gray mold epidemics on grapevine. This new species has been deposited in the MycoBank international database.

Fenhexamid Resistance in the Botrytis Species Complex, Responsible for Grey Mould Disease

“…In the same line, monitoring started before the introduction of fenhexamid, show that the variations in frequencies of B. pseudocinerea -naturally resistant to fenhexamid -in grey mould populations, seem to be independent of selection by fenhexamid. B. cinerea and B. pseudocinerea are found in sympatry on the same hosts, but clearly differ in their phenology, demonstrating differences in ecological niche (Walker et al, 2011): although present at low frequencies (0-15 %), B. pseudocinerea is predominantly found in spring populations and has only a reduced impact on grey mould epidemics.…”

“…The other species, called Botrytis pseudocinerea, has been found at low frequency in French populations. This species is morphologically indistinguishable from B. cinerea sensu stricto, but Walker et al (2011) established several molecular markers to distinguish both species. In addition B. pseudocinerea has a different pattern of fungicide susceptibility (phenotype HydR1), displaying natural resistance to fenhexamid and hypersensitivity to fenpropidin and edifenphos (Leroux et al, 2002).…”

“…Another example is Rhizoctonia solani which is subdivided into different anastomosis groups some of which are tolerant to pencycuron, an anti-microtubular agent (Campion et al, 2005). Also in the case of grey mould, it became clear that the species later on named Botrytis pseudocinerea a close relative of B. cinerea, was naturally resistant to fenhexamid at the stage of mycelial growth (Fournier et al, 2005, Walker et al, 2011. Later, resistant isolates were selected from the B. cinerea sensu stricto populations, initially sensitive to fenhexamid.…”

Gray mold caused by Botrytis cinerea limits grape production in Chile

“…This Lorenzini and Zapparoli, 2014;Walker et al, 2011;Zhou et al 2014). Similarly, phylogenetic analysis suggests the presence of cryptic species in B. cinerea from stone fruits in Chile (Ferrada et al, 2014).…”

“…Isolates belonging to Group I have been identified as B. pseudocinerea sp. nov. (Walker et al, 2011), and these isolates appeared to play a minor role in the gray mold epidemiology of grapevines (Vercesi et al, 2014).…”