Identification and Pathogenicity of Biscogniauxia and Sordaria Species Isolated from Olive Trees

Abstract

A field investigation of olive trees in Istria, Croatia, revealed branch dieback and cracked bark. Samples of diseased branches were collected from eight different locations and analysed. Additionally, meteorological data from two locations were analysed to determine if there was a connection between climatic changes and the appearance of pathogens in the region. Pathogenicity tests were conducted on olive seedlings. This study provides a description of Biscogniauxia and Sordaria species’ morphology and elucidates their phylogeny based on the internal transcribed spacer (ITS), beta-tubulin (TUB2) and translation elongation factor 1-alpha (TEF1- α) regions. This research represents the first documented occurrence of Biscogniauxia mediterranea causing charcoal disease in olive trees in Croatia. Additionally, it is the first report of Biscogniauxia nummularia (Bull.) Kuntze and Sordaria fimicola causing diseases in olive trees anywhere in the world. Furthermore, this study marks one of the initial forays into molecular investigations of these species isolated from olive trees. Considering the potential threat posed by the inherent aggressiveness of Biscogniauxia species, further research is deemed necessary to curb the development of charcoal disease.

A New Species of Biscogniauxia Associated with Pine Needle Blight on Pinus thunbergii in China

“…In 2019, B. nummularia was first recorded in southern Poland as an endophyte of white fir (Abies alba) and Pinus × rhaetica Brugger [65,66]. Research has illuminated the endophytic characteristics of B. nummularia, enabling it to swiftly transition from a benign endophyte to a primary pathogen [67][68][69]. Similarly, Biscogniauxia, typically found in woody plants, has also been isolated from pines such as Pinus koraiensis, firs such as Abies nephrolepis, and Douglas fir, as well as from Taxus cuspidata as an endophyte [70].…”

“…Due to imbalances in nutrient exchange, environmental changes, and change in host, endophytes can transit into pathogens under such circumstances [72]. Biscogniauxia is globally distributed, usually acting as an ubiquitous wood decomposer and a common endophyte [69]. There is substantial evidence that Biscogniauxia species exist as endophytes within healthy trees and later become pathogenic to plants when adverse stress occurs [70,73].…”