Pomegranate Woody Mycobiota Associated with Wood Decay

TL;DR

This study identifies fungal species linked to wood decay in pomegranate trees in Italy, emphasizing the role of Neofusicoccum parvum and Diaporthe species in causing the disease.

Contribution

The study integrates traditional and molecular methods to reveal the complex fungal community associated with pomegranate wood decay syndrome.

Findings

Neofusicoccum parvum was confirmed as a significant pathogen causing wood browning in pomegranate trees.

Diaporthe species showed variable virulence, with Diaporthe eres consistently demonstrating pathogenic activity.

Metabarcoding revealed 289 fungal taxa, indicating higher diversity in symptomatic wood compared to asymptomatic sections.

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, and progressive 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 variable 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 findings 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 wood diseases in pomegranate orchards.

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