While much is known of the identities and specificity of pathogens, pests, and symbionts in agriculture and forest management systems, the diversity and complexity of natural systems presents significant challenges for characterizing and identifying cryptic plant-microbe interactions. Pathogenic fungi account for significant mortality in tropical seedling communities and their host-specific interactions can influence plant community dynamics through negative feedbacks. Conversely, there is evidence that microbial symbionts, acting through positive feedbacks, can dampen diversity-enhancing effects of plant diseases at the community level.
Results/Conclusions
Culture-based surveys of leaf, stem, root, and seed-associated microfungi of healthy and diseased seedlings from three Neotropical forests: Chiquibul Maya Mountain Forest Reserve, Belize; La Selva, Costa Rica; and Barro Colorado National Monument, Panama show non-asymptotic species (operational taxonomic unit) accumulation curves. Genetic characterization, using the nrITS gene region, of fungal taxa infecting a range of tropical seedling hosts highlights the predominance of low specificity of plant-associated fungi in species rich communities. Common garden field experiments and greenhouse inoculation trials reveal complex interactions that may in part reflect the variation among individual plant micro- and mycobiomes. While the majority of fungal taxa were found to associate with all surveyed plant species, >30% of non-singletons were only isolated from one plant species. Accumulating evidence shows that endemic plant diseases are a crucial component in maintaining biodiversity and ecosystem services, and further characterization of these complex interactions could shed light on potential emerging and invasive diseases.