Identificação de espécies de Colletotrichum associadas com videiras e atividades antifúngica de monoterpenos sobre Colletotrichum spp. e Saccharomyces cerevisiae

Abstract

Ripe grape rot is one of the main diseases that occur in vineyards in southern Brazil, however, there is little information about the species of fungi responsible for the disease. Essential oils and their major compounds, monoterpenes, are considered alternatives for the control of fungal diseases, such as the grape ripe rot caused by Colletotrichum species. However, the mode of action of the monoterpenes has yet to be elucidated. The study aimed at the isolation and identification of Colletotrichum species from grapevines with symptoms of grape ripe rot, as well as the evaluation of fungicidal activity and mode of action of monoterpenes on isolates of Colletotrichum and the model yeast Saccharomyces cerevisiae. A total of 61 isolates were isolated from grapes with symptoms of grape ripe rot, the samples were identified by sequencing and phylogenetic analysis of GAPDH, TUB2, LSU, and ITS. Data showed the presence of six Colletotrichum species, C. viniferum (23), C. fructicola (22), C. kahawae (6), C. nymphaeae (7), C. limitticola (1) e C. karstii (2). Highlighting C. limitticola and C. karstii, which by the first time were associated with the grape ripe rot. Then, the fungicidal activity of 20 monoterpenes was evaluated on Colletotrichum isolates and S. cerevisiae. It was observed that the oxygenated monoterpenes showed greater antifungal activity compared to the other groups. Citral and geraniol monoterpenes showed the highest activity on Colletotrichum and S. cerevisiae. The mode of action of these monoterpenes on Colletotrichum was associated with a loss of cell membrane integrity, intracellular reactive oxygen species accumulation, although without evidence of loss of mitochondrial membrane potential. In addition, in S. cerevisiae was observed that citral and geraniol treatments caused loss of cell membrane and cell wall integrity, intracellular reactive oxygen species accumulation, and metacaspase-dependent apoptosis evidence, in which the Δyca1 mutant showed greater resistance to both monoterpenes. This study contributes to a better understanding of Colletotrichum species associated with grape ripe rot, moreover, shows alternatives for this fungus control through monoterpenes utilization.