ARABIDOPSIS GENES REGULATED BY THE INTERACTION WITH ERYSIPHE CICHORACEARUM.

GEORGINA FABRO; MARIA ELENA ALVAREZ

Cordoba, Argentina

Congreso; XXXVIII REUNION ANUAL SAIB (SOCIEDAD ARGENTINA DE BIOQUIMICA Y BIOLOGIA MOLECULAR); 2002

SAIB

We are studying the molecular bases of plant-pathogen interactions in the Arabidopsis thaliana - Erysiphe cichoracearum model system. We are interested in identify novel host genes specifically activated at early stages of interactions leading to either plant disease or resistance. Using a unique fungal virulent isolate to challenge three host ecotypes with differential fungal susceptibility (Col-0>Te-0>Kas-1), we have defined the limiting steps for the successful development of fungal infection. Microarray assays were applied to identify plant genes specifically induced at the initial limiting step (haustorium formation). Clustering analysis of four biological replicates was applied to select genes displaying 2.5-fold induction/repression, among 15.000 redundant ESTs loaded on the array. Seventeen genes were selected under these conditions and Northern blot assays confirmed the differential expression of some of them. A net induction of the At2g40080 gene (unknown function) is specifically detected before haustorium formation in susceptible plants (Col-0), while a weak and delayed activation is observed in the resistant ecotype (Te-0). At2g40080 is not induced by either compatible or incompatible bacterial infections suggesting that its function could be particularly required in fungal infections. Interestingly, Te-0 infected plants allow the fungus to built functional haustoria which are able to drive aminoacid uptake. Moreover, this non-susceptible ecotype does not exhibit physiological features of gene-for-gene resistance (i.e. cell death) suggesting that the At2g40080