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The Hemileia vastatrix effector Hv EC ‐016 suppresses bacterial blight symptoms in coffee genotypes with the S H 1 rust resistance gene

2016; Wiley; Volume: 213; Issue: 3 Linguagem: Inglês

10.1111/nph.14334

1469-8137

Thiago Maia, Jorge L. Badel, Gustavo Marin‐Ramirez, Cynthia de Melo Rocha, Michelle Bayer Fernandes, José Cleydson F. Silva, Gilson M. de Azevedo‐Junior, Sérgio Hermínio Brommonschenkel,

Plant-Microbe Interactions and Immunity

Summary A number of genes that confer resistance to coffee leaf rust ( S H 1– S H 9) have been identified within the genus Coffea , but despite many years of research on this pathosystem, the complementary avirulence genes of Hemileia vastatrix have not been reported. After identification of H. vastatrix effector candidate genes ( Hv EC s) expressed at different stages of its lifecycle, we established an assay to characterize Hv EC proteins by delivering them into coffee cells via the type‐three secretion system (T3 SS ) of Pseudomonas syringae pv. garcae ( Psgc ). Employing a calmodulin‐dependent adenylate cyclase assay, we demonstrate that Psgc recognizes a heterologous P. syringae T3 SS secretion signal which enables us to translocate Hv EC s into the cytoplasm of coffee cells. Using this Psgc ‐adapted effector detector vector ( EDV ) system, we found that Hv EC ‐016 suppresses the growth of Psgc on coffee genotypes with the S H 1 resistance gene. Suppression of bacterial blight symptoms in S H 1 plants was associated with reduced bacterial multiplication. By contrast, Hv EC ‐016 enhanced bacterial multiplication in S H 1‐lacking plants. Our findings suggest that Hv EC ‐016 may be recognized by the plant immune system in a S H 1‐dependent manner. Thus, our experimental approach is an effective tool for the characterization of effector/avirulence proteins of this important pathogen.