Proteomic and secretomic response of an African Armillaria species to iron.

Armillaria species have attracted considerable research interest because they are widely distributed, mostly plant-pathogenic, and exhibit unique characteristics. Abiotic factors influence intra- and inter-species variations in pathogenicity and/or virulence of these fungi. However, the mechanisms involved in causing these variations are not well understood. Iron is an indispensable element in several molecular and biological processes. Yet, excessive abundance of iron can be toxic to organisms due to Fenton-like reactions. This study aimed to gain insights into the type and extent of iron-responsive proteomic and secretomic changes in Armillaria sp. strain CMW4456 cultured in liquid media supplemented with iron using a multi-omics approach. Significant iron-dependent alterations of proteins involved in metabolism and growth were observed in the proteomes and secretomes. Iron supplementation at 100µM did not elicit an oxidative stress response by the fungus. Our analyses revealed three putative siderophore biosynthetic gene clusters (BGCs) in the genome and expression of proteins encoded by some BGC genes in the proteome. This knowledge contributes to a better understanding of the mechanisms employed by an Armillaria sp. in response to iron, gives insights into possible modes for inhibiting or attenuating pathogenicity and/or virulence of Armillaria spp., and can be valorised for more biotechnological applications.