Unravelling Hyaloperonospora arabidopsidis effector functions in A. thaliana

ADRIANA CABRAL; GEORGINA FABRO

Birnham, Escocia, Reino Unido

Congreso; Oomycete Molecular Genetics Network 2008; 2008

Oomycete Molecular Genetics Network

Host-pathogen interactions involve a complex interplay between organisms. Pathogens use a wide range of effectors to gain access to resources available in their hosts, and plants can activate a defence network aimed at preventing invasion and eliminating infecting pathogens. This co-evolutionary interaction imposes an intense selective pressure on both organisms. The oomycete Hyaloperonospora arabidopsidis is a naturally occurring pathogen of Arabidopsis. As an obligate biotroph, Hpa requires living host tissue for growth and reproduction. Little is still known about how oomycete pathogens manipulate their hosts to establish a successful infection. To gain insight into these processes, we initiated the characterization of Hpa effector proteins. We focused our analyses on the class of secreted proteins translocated into the plant cell that are characterized by the presence of a RXLR motif. Hpa genome mining and EST-sequencing allowed the identification of about 200 RXLR candidate effectors A total of 105 RXLR genes expressed during infection have already been cloned. These genes are now being screened for possible in planta effector function by delivery of RXLR proteins into the plant cytoplasm using the type III secretion system (TTSS) of the bacterial plant pathogen Pseudomonas syringae (EDV assay established by Sohn et al., 2007). We will report on the results of potential effector activities related to enhanced bacterial virulence and/or suppression of PAMP triggered immunity, as well as possible avirulence functions.