An isolate morphologically and phylogenetically distinct from Botrytis cinerea obtained from withered grapes possibly represents a new species of Botrytis

Grapes kept after harvest for withering in drying fruit rooms (fruttaio) are highly susceptible to Botrytis cinerea infection. A taxonomically undefined isolate (B83) was identified during a survey of B. cinerea populations in these specific environments. This isolate yielded negative results in B. cinerea-specific PCRs and displayed a different colony morphology on potato dextrose agar. Based on this data, the isolate underwent a taxonomic investigation. Sequencing of the ITS-5·8S-ITS2 region indicated that the isolate belongs to the Botrytis genus. IGS-RFLP analysis revealed that Botrytis sp. B83 was a different haplotype from genotypes of indigenous B. cinerea strains. Comparative sequence analysis of three housekeeping genes, G3PDH, HSP60 and RPB2, showed that the isolate constitutes a taxon related to Botrytis aclada, distant from B. cinerea. A phylogenetic tree built with NEP genes was in agreement with the combined tree built with G3PDH, HSP60 and RPB2 sequences. Botrytis sp. B83 is morphologically similar to B. aclada. Conversely, its host range indicates that it is polyphagous like B. cinerea, despite its lower virulence. This study provides evidence for the existence of a new species of Botrytis. Nevertheless, the description of only a single isolate and the need for further information on genetic divergence, reproductive isolation and host preference, prevent the classification and formal description of a new taxon.