Recently, attention has been shifting toward the perspective of the existence of plants and microbes as a functioning ecological unit. However, studies highlighting the impacts of the microbial community on plant health are still limited. In this study, fungal community (mycobiome) of leaf, root, and soil of symptomatic leaf-spot diseased (SS) oil palm were compared against asymptomatic (AS) trees using ITS2 rRNA gene metabarcoding. A total of 3,435,417 high-quality sequences were obtained from 29 samples investigated. Out of the 14 phyla identified, Ascomycota and Basidiomycota were the most dominant accounting for 94.2 and 4.7% of the total counts in AS, and 75 and 21.2% in SS, respectively. Neopestalotiopsis is the most abundant genus for AS representing 8.0% of the identified amplicons compared to 2.0% in SS while Peniophora is the most abundant with 8.6% of the identified amplicons for SS compared to 0.1% in AS. The biomarker discovery algorithm LEfSe revealed different taxa signatures for the sample categories, particularly soil samples from asymptomatic trees, which were the most enriched. Network analysis revealed high modularity across all groups, except in root samples. Additionally, a large proportion of the identified keystone species consisted of rare taxa, suggesting potential role in ecosystem functions. Surprisingly both AS and SS leaf samples shared taxa previously associated with oil palm leaf spot disease. The significant abundance of Trichoderma asperellum in the asymptomatic root samples could be further explored as a potential biocontrol agent against oil palm disease.

Several economically important diseases of forest trees and agricultural crops in many parts of the world have been linked to the ascomycete fungal pathogen Thielaviopsis paradoxa. This study compared the growth rate of 41 isolates of T. paradoxa sourced from different hosts and two countries (Nigeria and Papua New Guinea (PNG)) under six temperature levels (22 °C, 25 °C, 30 °C, 32 °C, 34 °C and 35 °C). Phylogenetic relationships were obtained from the analysis of their nuclear ribosomal DNA internal transcribed sequence (ITS) data. While all the isolates from PNG and few from Nigeria grew optimally between 22 °C and 32 °C, the majority had their highest growth rate (2.9 cm/day) between 25 °C and 32 °C. Growth performances were generally low between 34 °C and 35 °C; no isolate from the sugar cane grew at these high temperatures. The oil palm isolate DA029 was the most resilient, with the highest growth rate (0.97 cm/day) at 35 °C. Phylogenetic analysis delineated five clusters: a very large clade which accommodates the majority (30 Nigerian and 3 PNG oil palm isolates) and four small clades containing two members each. To a large extent, the clustering pattern failed to address the temperature–isolate relationship observed. However, only the four small clades represent isolates with similar temperature tolerances. It is most likely that wider and robust analyses with more diverse isolates and genetic markers will provide better insight on thermal resilience of T. paradoxa. Additionally, future research to establish relationships between vegetative growth at different temperatures and of different pathogenicity and disease epidemiology merits being explored. The results might provide useful information for the formulation of effective management and control strategies against the pathogen, especially in this era of climate change.

Forest trees are ecologically and economically vital, contributing to carbon sequestration, biodiversity conservation, pollution mitigation, and renewable bioenergy. However, forests worldwide are increasingly threatened by interacting biotic and abiotic stressors, including pathogens, insect pests, drought, heat, and extreme weather events driven by climate change. Drought and heat stress trigger complex physiological and metabolic responses in trees that can reshape their resistance to pathogens. While moderate stress may activate protective mechanisms, severe stress can cause cellular damage, dehydration, and reactive oxygen species accumulation, weakening defense capacity. Emerging evidence highlights additional layers of regulation, including epigenetic mechanisms and the role of beneficial microbiomes in enhancing tree resilience under combined environmental and pathogen pressures. Breeding and genetic improvement are also essential for strengthening adaptation and resistance to emerging diseases. Although advances in forest genetics, long-term field studies, and tree genomics are improving our predictive capacity, major knowledge gaps remain. Addressing how forest trees respond to pathogens under climate change will require multidisciplinary approaches integrating molecular biology, multiomics, big data analytics, remote sensing, ecology, and climate modelling.