Espécies do complexo Fusarium fujikuroi associadas à podridão da coroa da banana: diversidade, patogenicidade, potencial micotoxigênico e sensibilidade à fungicida

Abstract

Banana (Musa spp.) is one of the most globally consumed fruits, valued for both its taste and nutritional importance. Brazil ranks among the largest banana producers in the world, holding a prominent position as the fourth largest producer. This fruit plays a significant role in the country's agricultural economy and in the diets of many Brazilians, besides being exported to various international markets. However, its commercialization is seriously affected by post- harvest diseases that cause considerable damage and losses. Crown rot, caused by a fungal complex including various Fusarium species, is the most devastating post-harvest disease of bananas. The Fusarium genus is a globally important group of fungi, not only due to its ability to cause plant diseases but also because it harbors toxigenic species. Among these, F. verticillioides and F. proliferatum, which cluster in the Fusarium fujikuroi species complex (FFSC), are associated with crown rot. Members of the FFSC can produce mycotoxins, primarily fumonisins (FBs), which are harmful to human and animal health. The most applied method of post-harvest control to manage banana crown rot is the use of fungicides. Therefore, the aim of the study was to characterize FFSC species causing banana crown rot, collected from markets and processing units, through molecular approaches involving sequencing of the EF1- α and RPB2 genes, test their pathogenicity and aggressiveness; assess their potential to produce mycotoxins by identifying FUM genes using specific oligonucleotides (FUM53F/FUM53F and VERT1/VERT2); and evaluate resistance to the fungicide Imazalil in vitro. Phylogenetic analyses characterized 64 isolates belonging to the FFSC; the identified species were F. musae, F. annulatum, F. sacchari, F. verticillioides, and F. pseudocircinatum. This is the first report of the species F. annulatum associated with crown rot worldwide. Nine isolates were positive for genes encoding fumonisin production; F. verticillioides, F. musae, F. annulatum, and F. pseudocircinatum species showed the presence of FUM1 and FUM8 genes, indicating their capability to produce fumonisin. Species differed in their ability to infect and cause damage, with F. musae being more aggressive, while F. verticillioides were non-pathogenic. FFSC isolates showed significant variability in sensitivity to the fungicide, with identification of isolates highly resistant to the fungicide Imazalil. This study brings new contributions regarding the diversity of etiological agents associated with banana crown rot in the Cariri region of Ceará, FFSC members, and the capacity of these species to produce fumonisins. Considering the relevance of bananas as one of the most consumed fruits in the Brazilian population's diet, our results contribute with new knowledge for future evaluation of mycotoxin quantification in banana fruits in Brazil. Since this study indicates a potential threat to the quality of Brazilian bananas. Keywords: aggressiveness; Fumonisin; DMI fungicide; post-harvest rot; fungicide resistance;