A comprehensive analysis of genes encoding small secreted proteins identifies candidate effectors in Melampsora larici-populina (poplar leaf rust).

Stéphane Hacquard (1) , David L. Joly (2) , Yao-Cheng Lin (3) , Emilie Tisserant (1) , Nicolas Feau (2) , Christine Delaruelle (1) , Valérie Legué (1) , Annegret Kohler (1) , Philippe Tanguay (2) , Benjamin Petre (1) , Pascal Frey (1) , Yves van de Peer (3) , Pierre Rouzé (3) , Francis Martin (1) , Richard C Hamelin (2, 4) , Sébastien Duplessis (1)

1 IAM - Interactions Arbres-Microorganismes
2 NRCan - Natural Resources Canada
3 UGENT - Universiteit Gent = Ghent University
4 UBC Faculty of Forestry - Faculty of Forestry [Vancouver]

The obligate biotrophic rust fungus Melampsora larici-populina is the most devastating and widespread pathogen of poplars. Studies over recent years have identified various small secreted proteins (SSP) from plant biotrophic filamentous pathogens and have highlighted their role as effectors in host-pathogen interactions. The recent analysis of the M. larici-populina genome sequence has revealed the presence of 1,184 SSP-encoding genes in this rust fungus. In the present study, the expression and evolutionary dynamics of these SSP were investigated to pinpoint the arsenal of putative effectors that could be involved in the interaction between the rust fungus and poplar. Similarity with effectors previously described in Melampsora spp., richness in cysteines, and organization in large families were extensively detailed and discussed. Positive selection analyses conducted over clusters of paralogous genes revealed fast-evolving candidate effectors. Transcript profiling of selected M. laricipopulina SSP showed a timely coordinated expression during leaf infection, and the accumulation of four candidate effectors in distinct rust infection structures was demonstrated by immunolocalization. This integrated and multifaceted approach helps to prioritize candidate effector genes for functional studies.

Mots clés: petite protéine secrétér; small secreted proteins

Domaines: Sciences du Vivant [q-bio]

Stéphane Hacquard, David L. Joly, Yao-Cheng Lin, Emilie Tisserant, Nicolas Feau, et al.. A comprehensive analysis of genes encoding small secreted proteins identifies candidate effectors in Melampsora larici-populina (poplar leaf rust).. Molecular Plant-Microbe Interactions, 2012, 25 (3), pp.279-293. ⟨10.1094/MPMI-09-11-0238⟩. ⟨hal-01267890⟩