Siderophore production in Botryosphaeriaceae fungi associated with grapevine trunk diseases

Fungi from the Botryosphaeriaceae are recognized as causal agents of dieback diseases in a variety of economically important woody plants, including grapevine. Some species produce secondary metabolites that may function as virulent factors. In some fungi, siderophores have been associated with pathogenicity. Siderophores constitute an essential group of secondary metabolites with diverse biological functions in microorganisms. Additionally, they have potential applications in medicine and biotechnology. The primary role of siderophore is to bind insoluble extracellular iron (Fe³⁺), which is then transported into the cell via siderophore-iron transporters. This study aimed to evaluate the siderophore production capability of several species within the Botryosphaeriaceae. A total of 25 isolates were assessed using CAS-agar and CAS-liquid assays. The universal CAS assay indicated that multiple types of siderophores are produced by Botryosphaeriaceae species. Particularly, Lasiodiplodia brasiliensis strains MXBCL28 and VSM18MX showed the highest siderophore production levels, exceeding 60 %, followed by Neofusicoccum australe UCD1467So with 57.2 %, and L. gilanensis UCD256Ma with 46.7 %. Partial purification and selective extraction of siderophores from L. brasiliensis MXLBC28, using solvents classified by chemical properties, revealed the presence of both hydroxamate- and catecholate-type siderophores. The catecholate-type siderophores caused stronger phytotoxic effects in grapevine leaf assays, suggesting greater tissue-damaging potential. These results enhance our understanding of secondary metabolite production in the Botryosphaeriaceae and provide insights into the potential role of siderophores in fungal pathogenicity. • Botryosphaeriaceae produce hydroxamate and catecholate siderophores. • Lasiodiplodia brasiliensis shows highest production of siderophores. • Lasiodiplodia brasiliensis siderophores are phytotoxic to grapevine leaves.