Metabarcoding analysis identifies the phyllosphere fungal communities associated with a newly emerged leaf fall disease in rubber plants in Indonesia

Abstrak

Leaf fall disease of Hevea brasiliensis in Indonesia and Southeast Asia is an emerging threat to rubber production. While tentatively associated with Pestalotiopsis, Colletotrichum, and Neopestalotiopsis species, the disease etiology remains poorly characterized. This study aimed to identify the fungal community associated with symptomatic rubber leaves using culture-independent ITS amplicon sequencing. Leaf samples representing three symptom severity levels were collected from Central Java and South Sumatra. Fungal community composition analysis revealed that geographic origin, rather than symptom severity, was the primary driver of community clustering. Phyllosticta and Colletotrichum were consistently dominant across all samples, with Phyllosticta displaying notably higher relative abundance. Phyllosticta was identified as a newly reported pathogen of H. brasiliensis. Minor proportions of Pestalotiopsis, Neopestalotiopsis, Corynespora, and Pestalotia were also detected. Multigene phylogenetic analysis (ITS and β-tubulin) revealed three major clades corresponding to Neopestalotiopsis, Pestalotiopsis, and Colletotrichum. Pathogenicity assays confirmed that representative isolates reproduced field symptoms. This first metagenomic assessment of the phyllosphere mycobiota in diseased rubber leaves identifies Phyllosticta as a critical yet overlooked component of the leaf fall disease complex, providing insights into fungal ecology and pathogenic interactions underlying this emerging production threat.

Kata kunci

• Fungal community
• ITS amplicon sequencing
• Leaf fall disease
• Phyllosticta
• Rubber