title: The Hemileia vastatrix effector HvEC-016 suppresses bacterial blight symptoms in coffee genotypes with the SH1 rust resistance gene.
abstract: A number of genes that confer resistance to coffee leaf rust (SH1-SH9) 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 (HvECs) expressed at different stages of its lifecycle, we established an assay to characterize HvEC proteins by delivering them into coffee cells via the type-three secretion system (T3SS) of Pseudomonas syringae pv. garcae (Psgc). Employing a calmodulin-dependent adenylate cyclase assay, we demonstrate that Psgc recognizes a heterologous P. syringae T3SS secretion signal which enables us to translocate HvECs into the cytoplasm of coffee cells. Using this Psgc-adapted effector detector vector (EDV) system, we found that HvEC-016 suppresses the growth of Psgc on coffee genotypes with the SH1 resistance gene. Suppression of bacterial blight symptoms in SH1 plants was associated with reduced bacterial multiplication. By contrast, HvEC-016 enhanced bacterial multiplication in SH1-lacking plants. Our findings suggest that HvEC-016 may be recognized by the plant immune system in a SH1-dependent manner. Thus, our experimental approach is an effective tool for the characterization of effector/avirulence proteins of this important pathogen.
authors.affiliation: Departamento de Fitopatologia and National Institute for Plant-Pest Interactions/Instituto de Biotecnologia Aplicada a Agropecuária-BIOAGRO, Universidade Federal de Viçosa, Viçosa, MG 36570-000, Brazil.
authors.forename: Thiago
authors.initials: T
authors.lastname: Maia
authors.affiliation: Departamento de Fitopatologia and National Institute for Plant-Pest Interactions/Instituto de Biotecnologia Aplicada a Agropecuária-BIOAGRO, Universidade Federal de Viçosa, Viçosa, MG 36570-000, Brazil.
authors.forename: Jorge L
authors.initials: JL
authors.lastname: Badel
authors.affiliation: Departamento de Fitopatologia and National Institute for Plant-Pest Interactions/Instituto de Biotecnologia Aplicada a Agropecuária-BIOAGRO, Universidade Federal de Viçosa, Viçosa, MG 36570-000, Brazil.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Marin-Ramirez
authors.affiliation: Departamento de Fitopatologia and National Institute for Plant-Pest Interactions/Instituto de Biotecnologia Aplicada a Agropecuária-BIOAGRO, Universidade Federal de Viçosa, Viçosa, MG 36570-000, Brazil.
authors.forename: Cynthia de M
authors.initials: CM
authors.lastname: Rocha
authors.affiliation: Departamento de Fitopatologia and National Institute for Plant-Pest Interactions/Instituto de Biotecnologia Aplicada a Agropecuária-BIOAGRO, Universidade Federal de Viçosa, Viçosa, MG 36570-000, Brazil.
authors.forename: Michelle B
authors.initials: MB
authors.lastname: Fernandes
authors.affiliation: Departamento de Fitopatologia and National Institute for Plant-Pest Interactions/Instituto de Biotecnologia Aplicada a Agropecuária-BIOAGRO, Universidade Federal de Viçosa, Viçosa, MG 36570-000, Brazil.
authors.forename: José C F
authors.initials: JC
authors.lastname: da Silva
authors.affiliation: Departamento de Fitopatologia and National Institute for Plant-Pest Interactions/Instituto de Biotecnologia Aplicada a Agropecuária-BIOAGRO, Universidade Federal de Viçosa, Viçosa, MG 36570-000, Brazil.
authors.forename: Gilson M
authors.initials: GM
authors.lastname: de Azevedo-Junior
authors.affiliation: Departamento de Fitopatologia and National Institute for Plant-Pest Interactions/Instituto de Biotecnologia Aplicada a Agropecuária-BIOAGRO, Universidade Federal de Viçosa, Viçosa, MG 36570-000, Brazil.
authors.forename: Sérgio H
authors.initials: SH
authors.lastname: Brommonschenkel
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000595:Amino Acid Sequence; D058947:Bacterial Secretion Systems; D001487:Basidiomycota / Q000235:genetics / Q000502:physiology*; D040503:Coffea / Q000235:genetics* / Q000382:microbiology*; D060467:Disease Resistance / Q000235:genetics*; D005091:Exons / Q000235:genetics; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D005800:Genes, Fungal; D017343:Genes, Plant; D005838:Genotype; D007438:Introns / Q000235:genetics; D010935:Plant Diseases / Q000382:microbiology*; D044224:Pseudomonas syringae / Q000254:growth & development / Q000472:pathogenicity*; D016415:Sequence Alignment
chemical_list: D058947:Bacterial Secretion Systems; D005656:Fungal Proteins; D000262:Adenylyl Cyclases
keywords: 
  Hemileia vastatrix
  ; Pseudomonas syringae pv. garcae; avirulence protein; coffee rust; effector delivery; effector prediction; necrosis suppression; plant immunity