TOWARDS THE IDENTIFICATION OF ARABIDOPSIS SUSCEPTIBILITY FACTORS PROMOTING THE PATHOGENICITY OF ERYSIPHE CICHORACEARUM

GEORGINA FABRO; LUCRECIA CAROT; SHAUNA SOMERVILLE; MARIA ELENA ALVAREZ

Cordoba

Congreso; XXXVII REUNION ANUAL SAIB (SOCIEDAD ARGENTINA DE BIOQUIMICA Y BIOLOGIA MOLECULAR); 2001

SAIB

Plant non-host resistance is developed by every plant species in response to the attack by the majority of microbial pathogens. This resistance is multigenic and is likely due to the absence of plant components (?susceptibility factors?, SF) required for completion of the pathogen infective cycle in planta. Despite the wide occurrence of this phenomenon in nature, little is known about its molecular bases including the identity of SFs. Our goal is to isolate Arabidopsis SFs that trigger pathogenicity steps of the biotrophic parasite E. cichoracearum. Microscopic quantification of the infective structures developed in challenged leaves (germ tube, haustorium, conidium) of Arabidopsis accessions with variable susceptibility levels (Col-0>Te-0>Kas-1), were used to define the limiting steps of the pathogenic process in each plant. Plant tissues isolated at those steps from susceptible and resistant plants were utilized for identification of SFs by proteomic assays in search of components only expressed under susceptible conditions. In addition, Arabidopsis genes responding to pathogen infection in a similar manner in susceptible and defense mutant plants were identified by microarrays. More than 30 candidate SF genes with altered expression at the time of haustorium formation were detected among ~7.800 genes examined (11.500 redundant EST clones). The molecular characterization of these genes is here presented.