Responses of woody hosts to Armillaria species infections: Current insights and knowledge gaps

Abstract

Armillaria, and the closely related genus Desarmillaria, are a diverse group of fungi with over 40 species. Many species of Armillaria cause Armillaria root rot in a wide range of hosts. This disease has caused severe losses in diverse ecosystems worldwide, in both natural and managed environments. Despite the considerable efforts invested in assessing the varying degrees of resistance among diverse woody hosts to Armillaria, most host screening studies have neglected the integration of concepts and mechanisms pertaining to woody host defense. While a modest body of knowledge exists concerning host defense mechanisms against Armillaria, the research is predominantly confined to selective host species within forest ecosystems. Thus, a multitude of theoretical and applied questions pertaining to the reactions and resistance of woody hosts to pathogenic Armillaria species continue to remain unanswered. The present review consolidates the current understanding surrounding defense mechanisms exhibited by diverse woody hosts in response to infection by pathogenic Armillaria species. Additionally, it outlines potential avenues for future research in this domain.