Recognition of floral homeotic MADS domain transcription factors by a phytoplasmal effector, phyllogen, induces phyllody

Kensaku Maejima, Ryo Iwai, Misako Himeno, Ken Komatsu, Yugo Kitazawa, Naoko Fujita, Kazuya Ishikawa, Misato Fukuoka, Nami Minato, Yasuyuki Yamaji, Kenro Oshima, Shigetou Namba

Research output: Contribution to journalArticlepeer-review

91 Citations (Scopus)


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'.

Original languageEnglish
Pages (from-to)541-554
Number of pages14
JournalPlant Journal
Issue number4
Publication statusPublished - May 2014
Externally publishedYes


  • Arabidopsis
  • MADS domain proteins
  • floral development
  • floral quartet model
  • phyllody
  • phytoplasma

ASJC Scopus subject areas

  • Genetics
  • Plant Science
  • Cell Biology


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