Résumé
Puccinia kuehnii, the causal agent of orange rust, is a fungal pathogen that induced significant losses to the sugarcane crop in Florida since 2007. During plant infection, rust fungi deliver effector proteins into host tissues to manipulate plant functions and promote parasitic growth. Identiflcation and functional characterization of secreted effectors are essential steps to understand the molecular basis of host-pathogen interactions. Like other biotrophic fungi, Puccinia species possess large repertoires of secreted proteins whose vast majority has no known function.The objective of our investigations is to identify genes encoding secreted proteins, including relevant disease-related candidate effectors that are expressed during sugarcane infection by the orange rust pathogen. In a first experiment, healthy leaves of sugarcane cultivars CPB9-2743 (susceptible to orange rust) and CP96-1252 (resistant) were inoculated with race 2743 of P. kuehnii. In a second experiment, healthy leaves of sugarcane cultivars CL85-1040 (susceptible) and CP96-1,252 (resistant) were inoculated with race 1040 of the pathogen. Total RNA was extracted at 0-72 days after inoculation and transcript expression was quantilified through Illumina RNA-sequencing. Differential gene expression profiling was then determined for the compatible and incompatible interactions using DESeq2. Ongoing work includes characterization of effector proteins differentiating races 1040 and 2743 of P. kuehnii. Our longterm goal is to identify a set of candidate effector proteins for identification of host defense related proteins in marker-assisted breeding of sugarcane.