Pomegranate Woody Mycobiota Associated with Wood Decay

Abstract

The rapid expansion of pomegranate (Punica granatum L.) cultivation in central and southern Italy has revealed emerging phytosanitary challenges, including “pomegranate wood decay syndrome”, characterised by cortical cankers, wood browning, andprogressive plant decline. This study investigates the fungal microbiota associated with symptomatic pomegranate wood using a combined approach of traditional fungal isolation and ITS2 metabarcoding analysis. Samples from two orchards in Lazio were examined, revealing a complex fungal community with a high prevalence of Neofusicoccum parvum (putative) and species belonging to the genus Diaporthe. Pathogenicity tests confirmed the role of N. parvum in causing significant wood browning, while other isolates showed vari able virulence. Statistical analyses validated the pathogenicity of select isolates, with the putative Diaporthe eres (Nitschke) consistently demonstrating potential pathogenic activity across all trials. Metabarcoding identified 289 taxa, highlighting a richer fungal diversity in the symptomatic wood compared to the asymptomatic sections. Notably, Coniella granati, previously implicated in pomegranate decline, was absent in the studied orchards. The f indings reveal that pomegranate wood decay is a complex syndrome driven by fungal pathogens and environmental stressors, such as low temperatures. This study highlights the value of integrative approaches for understanding and managing fungal-associated wooddiseases in pomegranate orchards.