Cercospora species cause pink spot disease on guava fruit in Brazil

Abstract

Guava producers in Brazil have reported the occurrence of small, pink spot lesions on the surface of fruits in orchards. Symptomatic fruits were harvested from commercial guava orchards, and 18 monosporic isolates were obtained. All tested isolates were pathogenic to guava fruit and showed colony and conidial characteristics indicative of cercosporoid fungi. Phylogenetic analysis of the concatenated gene sequences showed that all isolates belonged to the genus Cercospora and clustered into four haplotypes. Conidia released 3-5 germ tubes, and penetration occurred through the stomata. All isolates produced cercosporin. Histopathological analyses showed that hyphal growth occurred intercellularly and that there was a collapse of epidermal and subepidermal cells in the injured areas. In addition, the oil cavities in the lesioned tissue had large numbers of lipid droplets compared with the nonlesioned tissue. This is the first report of Cercospora spp. as the causal agent of pink spot disease of guava fruit in Brazil.