Molecular identification of Botrytis cinerea, Botrytis paeoniae and Botrytis pseudocinerea associated with gray mould disease in peonies (Paeonia lactiflora Pall.) in Southern Chile

Abstract Background In Chile, the peony is the most important ornamental flower exported from the country. Gray mould is a phytopathological problem of this crop. This disease is caused by Botrytis cinerea and Botrytis paeoniae . Aims We carried out the first survey of Botrytis species associated with peony gray mould in Southern Chile to estimate the diversity of these pathogens. Methods Diseased peony leaves were collected from seven locations in Southern Chile covering a distance of 300 km. The Botrytis isolates obtained were studied by morphological and molecular methods. Finally, a PCR assay using primers based on the necrosis and ethylene-inducing protein gene ( nep 1) was used to specifically identify B. paeoniae . Results Seventeen isolates belonging to Botrytis genus were obtained, and all of them were pathogenic to peonies when inoculated in plants grown in a greenhouse. Morphological analyses showed that four isolates shared common characteristics, which distinguish them from the rest. Homology and phylogenetic analysis of G3PDH, as well as determination of the Bc-hch allele, allowed us to identify 12 isolates as B. cinerea , 4 as B. paeoniae and one isolate as Botrytis pseudocinerea . The PCR assay was found to be specific to B. paeoniae , amplifying a single band of 470 bp. Conclusions Three Botrytis species involved in peony gray mould disease are present in Chile. This is the first time that both B. paeoniae and B. pseudocinerea have been reported to be present in the country and also that they affect peonies. Finally, to our knowledge, the PCR based method herein described is the first of its kind to be used to identify B. paeoniae .