Molecular study of the pathogenic fungus Puccinia psidii Winter, the causal agent of rust, in vitro and during their interaction with Eucalyptus spp

Abstract

Brazil is a leading global producer of Eucalyptus spp., though productivity has been hampered by the occurrence of injuries caused by pathogens such as Puccinia psidii Winter, the causal agent of rust. Disease management could be improved by understanding the pathogenicity mechanisms of this fungus but little is known about its biology and the interaction processes with their host. One of the greatest barriers limiting the molecular study of this fungus is its biotrophic lifestyle, with limited in vitro development. Consequently, many studies of biotrophic fungal pathogens have been conducted mainly in planta at the end of the infection stage during the onset of symptoms, and data from early stages of infection when several typical structures of the pathogen are formed, is masked by the plant material which is too difficult to be completely removed from the samples. Thus, this project aims (I) the improvement of a protocol to increase the uredospore germination rate, (II) to induce the structural morphogenesis of the pathogen P. psidii in vitro and (III) to identify candidate genes related to morphogenesis of early infection structures, fungal pathogenicity and virulence factors through RNAseq analysis. Transcriptomics data of fungal in vitro and in planta development will be validated by qPCR. Additionally, leaf cuticular wax metabolites from resistant and susceptible genotypes of Eucalyptus grandis will be investigated to identify compounds related to genotype resistance or to the signaling of the beginning of germination and host infection. The present project will substantially collaborate with the better understanding of fungal pathogenicity mechanisms and which plant metabolites are involved in the early stages of plant-pathogen interaction, contributing for the development of pathogen control strategies in the future. (AU)