Curvularia soli causes a new leaf spot disease on Pereskia aculeata

Abstract

Pereskia aculeata (Barbados gooseberry) is a vegetable member of the Cactaceae family. Pereskia aculeata leaves are highly valued for culinary use in some Brazilian regions, mainly in Minas Gerais. In March 2023, severe leaf spot disease affecting P. aculeata plants was observed in Viçosa, Minas Gerais, Brazil. Notably, we found that Curvularia sp. was associated with disease symptoms. However, the fungus Curvularia has not been reported to cause any diseases in P. aculeata. Given the absence of any previous records documenting this fungus as a pathogen for this host, this study aimed to identify Curvularia species associated with leaf spots on P. aculeata and elucidate the etiology of the disease. The fungus was identified as Curvularia soli based on its morphological characteristics and molecular features using glyceraldeyde-3-phosphate dehydrogenase (GAPDH) and translation elongation factor 1-α (TEF1-α) for phylogenetic analyses. Healthy P. aculeata plants were inoculated with a representative isolate of C. soli and the same symptoms as observed in the field were reproduced. All steps were performed to fulfill Koch's postulates and confirm the etiology of the disease.