Around the world in eight white rot species: Assessment of enzymatic and non-enzymatic wood decay pathways of worldwide Esca Complex of Diseases (ECD) associated basidiomycetes

Abstract

Esca Complex of Diseases (ECD) is widespread in viticultural areas worldwide, posing a serious risk to modern viticulture. The role of basidiomycetes in the onset of foliar symptoms has recently been reconsidered, highlighting a link between the reduction in these symptoms and the presence of Fomitiporia mediterranea in vines. As several basidiomycetes have been associated with wood decay in grapevine, understanding their degradation mechanisms could help unravel the role of wood degradation in ECD. Thus, a collection of ECD-associated basidiomycetes, including F. capensis, F. langloisii, F. polymorpha, F. australiensis, Tropicoporus texanus, Inonotus vitis, and Stereum hirsutum, was examined in addition to F. mediterranea. Our study investigates the production and activity of lignocellulosic enzymes (particularly class-II peroxidases and laccases), along with the low molecular weight compounds (LMWC) in the secretome of these fungi, to assess their ability to perform the Chelator-Mediated-Fenton (CMF) pathway. Results highlight the production of ligninolytic enzymes with low production of active manganese peroxidases and a virtually total absence of lignin peroxidase activity. Additionally, the study confirms that the CMF mechanism is widespread among these fungi, with all LMW secretomes fulfilling the required steps of the CMF mechanism. This study provides critical insights into the degradation strategies of ECD-associated white rot agents, offering potential new perspectives on studying ECD symptomatology and developing targeted control strategies. The findings emphasize the need to consider the CMF mechanism in the context of fungal wood degradation and its potential role in ECD development.