Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Frontiers in Plant Science art. 88 [17 ] appressorium coffee leaf rust germinating urediniospore haustorium pyrosequencing transcriptome 2014 fdi:010061842 ENG Frontiers in Plant Science 1664-462X ISI:000332731900001 10.3389/fpls.2014.00088 https://www.documentation.ird.fr/hor/fdi:010061842 https://www.documentation.ird.fr/intranet/publi/2014/04/010061842.pdf 5 Horizon (IRD) Hemileia vastatrix is the causal agent of coffee leaf rust, the most important disease of coffee Arabica. In this work, a 454-pyrosequencing transcriptome analysis of H. vastatrix germinating urediniospores (gU) and appressoria (Ap) was performed and compared to previously published in planta haustoria-rich (H) data. A total of 9234 transcripts were identified and annotated. Ca. 50% of these transcripts showed no significant homology to international databases. Only 784 sequences were shared by the three conditions, and 75% were exclusive of either gU (2146), Ap (1479) or H (3270). Relative transcript abundance and RT-qPCR analyses for a selection of genes indicated a particularly active metabolism, translational activity and production of new structures in the appressoria and intense signaling, transport, secretory activity and cellular multiplication in the germinating urediniospores, suggesting the onset of a plant-fungus dialogue as early as at the germ tube stage. Gene expression related to the production of carbohydrate-active enzymes and accumulation of glycerol in germinating urediniospores and appressoria suggests that combined lytic and physical mechanisms are involved in appressoria-mediated penetration. Besides contributing to the characterization of molecular processes leading to appressoria-mediated infection by rust fungi, these results point toward the identification of new H. vastatrix candidate virulence factors, with 516 genes predicted to encode secreted proteins. 076 UR186