CONICET | Buscador de Institutos y Recursos Humanos

Plant-microbes interactions may potentially affect fitness and evolution of involved species. Therefore, it is interesting to understand the underlying mechanisms that maintain mutualistic interactions (i.e. both partners are benefited) under natural and human selection context. Endophytes of genus Neotyphodium are asexual fungi commonly present in allogamous cool-season grasses. Under certain context, host plants obtain protection against stresses meanwhile fungi obtain nutrients from the apoplast and a means of dissemination through the seeds. Here we propose a model that considers the potential responses of host plant fitness, genetic specificity between partners, mutualism effectiveness, and endophyte transmission efficiency to the genetic distance among mating host parents. In this model, gene flow is viewed as a source of genetic variability promoting host fitness and raw material for evolution. Since endophyte success depends on host plant fitness, we propose that the endophyte-grass interaction might work as an integrated entity. Despite the apparent trade-off between genetic specificity and host fitness in relation to the genetic distance among mating parents, the model assumes that a certain heterosis level is needed for the mutualism effectiveness. Although genetic specificity could be the highest at low genetic distance among mating parents, the mutualism effectiveness and the transmission efficiency will be low in inbreeding depressed hosts. According with the increment in the genetic distance among mating parents, the mutualism effectiveness and the transmission efficiency will also be increased. However, this relationship will be positive until a level where genetic specificity is disrupted because the genetic distance among mating parent is extremely high (out-breeding depression). By testing the predictions emergent from the model, we will take advantage of our understanding of the coevolutionary origin and future directions of the endophyte-grass interaction.