Botrytis californica, a new cryptic species in the B. cinerea species complex causing gray mold in blueberries and table grapes

Abstract

The Botrytis cinerea species complex comprises two cryptic species, originally referred to Group I and Group II based on Bc-hch gene RFLP haplotyping. Group I was described as a new cryptic species B. pseudocinerea. During a survey of Botrytis spp. causing gray mold in blueberries and table grapes in the Central Valley of California, six isolates, three from blueberries and three from table grapes, were placed in Group I but had a distinct morphological character with conidiophores significantly longer than those of B. cinerea and B. pseudocinerea. We compared these with B. cinerea and B. pseudocinerea by examining morphological and physiological characters, sensitivity to fenhexamid and phylogenetic analysis inferred from sequences of three nuclear genes. Phylogenetic analysis with the three partial gene sequences encoding glyceraldehyde-3-phosate dehydrogenase (G3PDH), heat-shock protein 60 (HSP60) and DNA-dependent RNA polymerase subunit II (RPB2) supported the proposal of a new Botrytis species, B. californica, which is closely related genetically to B. cinerea, B. pseudocinerea and B. sinoviticola, all known as causal agents of gray mold of grapes. Botrytis californica caused decay on blueberry and table grape fruit inoculated with the fungus. This study suggests that B. californica is a cryptic species sympatric with B. cinerea on blueberries and table grapes in California.

• cryptic species
• gray mold
• phylogenetic analysis
• plant pathogen
• Vaccinum corymbosum
• Vitis vinifera

ACKNOWLEDGMENTS

We thank S. Pelham for technical support and F. Dugan for pre-submission review. This research was supported in part by the California Table Grape Commission. Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendations or endorsement by the U.S. Department of Agriculture. USDA is an equal opportunity provider and employer.