title: Recognition of floral homeotic MADS domain transcription factors by a phytoplasmal effector, phyllogen, induces phyllody.
abstract: Plant pathogens alter the course of plant developmental processes, resulting in abnormal morphology in infected host plants. Phytoplasmas are unique plant-pathogenic bacteria that transform plant floral organs into leaf-like structures and cause the emergence of secondary flowers. These distinctive symptoms have attracted considerable interest for many years. Here, we revealed the molecular mechanisms of the floral symptoms by focusing on a phytoplasma-secreted protein, PHYL1, which induces morphological changes in flowers that are similar to those seen in phytoplasma-infected plants. PHYL1 is a homolog of the phytoplasmal effector SAP54 that also alters floral development. Using yeast two-hybrid and in planta transient co-expression assays, we found that PHYL1 interacts with and degrades the floral homeotic MADS domain proteins SEPALLATA3 (SEP3), APETALA1 (AP1) and CAULIFLOWER (CAL). This degradation of MADS domain proteins was dependent on the ubiquitin-proteasome pathway. The expression of floral development genes downstream of SEP3 and AP1 was disrupted in 35S::PHYL1 transgenic plants. PHYL1 was genetically and functionally conserved among other phytoplasma strains and species. We designate PHYL1, SAP54 and their homologs as members of the phyllody-inducing gene family of 'phyllogens'.
authors.affiliation: Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Kensaku
authors.initials: K
authors.lastname: Maejima
authors.forename: Ryo
authors.initials: R
authors.lastname: Iwai
authors.forename: Misako
authors.initials: M
authors.lastname: Himeno
authors.forename: Ken
authors.initials: K
authors.lastname: Komatsu
authors.forename: Yugo
authors.initials: Y
authors.lastname: Kitazawa
authors.forename: Naoko
authors.initials: N
authors.lastname: Fujita
authors.forename: Kazuya
authors.initials: K
authors.lastname: Ishikawa
authors.forename: Misato
authors.initials: M
authors.lastname: Fukuoka
authors.forename: Nami
authors.initials: N
authors.lastname: Minato
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamaji
authors.forename: Kenro
authors.initials: K
authors.lastname: Oshima
authors.forename: Shigetou
authors.initials: S
authors.lastname: Namba
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D035264:Flowers / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D054884:Host-Pathogen Interactions; D015151:Immunoblotting; D026161:MADS Domain Proteins / Q000235:genetics / Q000378:metabolism*; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D045582:Phytoplasma / Q000235:genetics / Q000378:metabolism*; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D030821:Plants, Genetically Modified; D011485:Protein Binding; D059748:Proteolysis; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; D001426:Bacterial Proteins; C091536:CAL protein, Arabidopsis; D018398:Homeodomain Proteins; D026161:MADS Domain Proteins; C121158:SEP3 protein, Arabidopsis; D014157:Transcription Factors
keywords: Arabidopsis; MADS domain proteins; floral development; floral quartet model; phyllody; phytoplasma