Hernán D. Capador-Barreto is a Postdoctoral Research Fellow at the Smithsonian Tropical Research Institute (STRI) in Panamá. His multidisciplinary and cross-latitudinal research combines forest genomics and plant pathology to understand the genetics and evolution of disease resistance traits in trees. He studied Biology and Industrial Microbiology at the Pontificia Universidad Javeriana in Bogotá, Colombia (B.Sc.) and Plant Biology (M.Sc) at Swedish University of Agricultural Sciences in Uppsala, Sweden (SLU). He received his PhD from the Department of Forest Mycology and Plant Pathology also at SLU, where he studied the genomics of disease resistance in Picea abies, a widely planted conifer in Europe. Currently he investigates how genetic variation in Virola nobilis (Wild nutmeg or Sangrillo) affects its susceptibility to soil pathogens and its distribution on Barro Colorado Island in the Republic of Panama.
Multiple soil-borne pathogens contribute to disease and mortality of Virola nobilis seedlings
H.D. CAPADOR-BARRETO, J. BALLESTEROS, K. BRODERS, E.R. SPEAR, S.J. WRIGHT
Smithsonian Tropical Research Institute, Panama City, Republic of Panama.
According to the Janzen-Connell hypothesis, conspecific negative density dependence (CNDD) maintains the exuberant plant diversity observed in tropical rainforests. Virola nobilis (syn. Virola surinamensis), a tree species native to Central America is a model species to study CNDD: Seedling mortality is high under conspecific V. nobilis trees, but toucans and monkeys disperse some seeds far from their mother tree, where survival is higher. Although it is generally accepted that natural enemies are responsible for CNDD in V. nobilis, it is unknown which microbes are driving it. Therefore, in this study we have characterized fungal pathogens infecting V. nobilis seedlings in Barro Colorado Island, in the Republic of Panama. We sowed seeds under conspecific trees and isolated fungi from symptomatic seedlings. Using infection assays in shade-houses we confirmed pathogenicity for several species of fungi in the Nectriaceae family. Isolates of Calonectria were among the most frequently isolated fungi and caused high mortality on V. nobilis seedlings. Additionally, we have characterized the fungal community using ITS metabarcoding from soil near V. nobilis trees and show that abundance of putative pathogens varies significantly between trees. In all, our results demonstrate the effect of several soil fungal species in seedling mortality and consequently the demographic dynamics of V. nobilis. Moreover, these results enable future studies to understand how plant-microbe interactions shape diversity in tropical forests.