title: Phytoplasma effector SAP54 induces indeterminate leaf-like flower development in Arabidopsis plants.
abstract: Phytoplasmas are insect-transmitted bacterial plant pathogens that cause considerable damage to a diverse range of agricultural crops globally. Symptoms induced in infected plants suggest that these phytopathogens may modulate developmental processes within the plant host. We report herein that Aster Yellows phytoplasma strain Witches' Broom (AY-WB) readily infects the model plant Arabidopsis (Arabidopsis thaliana) ecotype Columbia, inducing symptoms that are characteristic of phytoplasma infection, such as the production of green leaf-like flowers (virescence and phyllody) and increased formation of stems and branches (witches' broom). We found that the majority of genes encoding secreted AY-WB proteins (SAPs), which are candidate effector proteins, are expressed in Arabidopsis and the AY-WB insect vector Macrosteles quadrilineatus (Hemiptera; Cicadellidae). To identify which of these effector proteins induce symptoms of phyllody and virescence, we individually expressed the effector genes in Arabidopsis. From this screen, we have identified a novel AY-WB effector protein, SAP54, that alters floral development, resulting in the production of leaf-like flowers that are similar to those produced by plants infected with this phytoplasma. This study offers novel insight into the effector profile of an insect-transmitted plant pathogen and reports to our knowledge the first example of a microbial pathogen effector protein that targets flower development in a host.
authors.affiliation: Department of Disease and Stress Biology , John Innes Centre, Norwich NR47UH, United Kingdom.
authors.forename: Allyson M
authors.initials: AM
authors.lastname: MacLean
authors.forename: Akiko
authors.initials: A
authors.lastname: Sugio
authors.forename: Olga V
authors.initials: OV
authors.lastname: Makarova
authors.forename: Kim C
authors.initials: KC
authors.lastname: Findlay
authors.forename: Victoria M
authors.initials: VM
authors.lastname: Grieve
authors.forename: Réka
authors.initials: R
authors.lastname: Tóth
authors.forename: Mogens
authors.initials: M
authors.lastname: Nicolaisen
authors.forename: Saskia A
authors.initials: SA
authors.lastname: Hogenhout
mesh_terms: D000818:Animals; D017360:Arabidopsis / Q000254:growth & development / Q000382:microbiology*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D035264:Flowers / Q000254:growth & development* / Q000382:microbiology; D006430:Hemiptera / Q000235:genetics / Q000382:microbiology; D054884:Host-Pathogen Interactions; D007303:Insect Vectors / Q000235:genetics; D045582:Phytoplasma / Q000378:metabolism / Q000472:pathogenicity*; D010935:Plant Diseases / Q000382:microbiology*; D030821:Plants, Genetically Modified / Q000382:microbiology
chemical_list: D001426:Bacterial Proteins