Rust Proteomics: Tools to Understand Effector Molecules

Stripe rust is a major constraint to wheat production worldwide. The causal agent is the fungus Puccinia striiformis f.sp. tritici (Pst). During infection, the fungus creates a specialized cellular structure within host cells called the haustorium which allows Pst to obtain the nutrients necessary for development and reproduction. Nevertheless, one of the main roles of the haustorium is thought to be the secretion of virulence molecules called ‘effectors’ . Effector molecules are proposed to manipulate the physiological and immune responses of host cells to facilitate fungal colonization. Despite the availability of large sets of predicted effector genes derived from genomic and transcriptomic data of Pst, the molecular events that underlie the synthesis and delivery of effectors, and their functions within the host cell, are largely unknown. In our research, the combination of transcriptomic and proteomic data from haustoria, germinated and ungerminated spores have been useful to determine the presence of effector candidates in each tissue. Furthermore, the correlation of transcriptomic and proteomic datasets suggests that the synthesis and deployment of some effector proteins could occur at different spatiotemporal sites, and could even have destinations other than the host cell cytoplasm. The development of molecular assays to investigate the role of predicted effectors detected at the proteomic level, and how their synthesis and deployment deregulation could influence it, are currently priorities in our laboratory. Together, these studies provide insights into the pathogenic strategies of Pst and open new avenues of research with potential in the design of novel disease control strategies.