The phytoplasma effector, Phyllogen, structurally mimics host plant MADS transcription factors

Abstract

Phytoplasmas are obligate plant pathogens that include species causing severe developmental abnormalities in diverse plant families. Phytoplasma infections may result in dwarfism, witches' broom, virescence and phyllody, the conversion of reproductive organs into leaf-like structures. Phyllody is due to the activity of phytoplasma effector proteins, called phyllogens, that interact with the host MADS transcription factor (MTF) network. This interaction was believed to be specific for members of the AP1/SEP/AGL6 superclade of tetrameric MTFs, key regulators of floral meristem identity and organogenesis. Here, we determined the molecular and atomic basis for the interaction between the phyllogen from Onions Yellow phytoplasma (PHYLOY) and the floral MTFs, APETALA1, SEPALLATA and AGAMOUS using biochemical, structural and genetic experiments. The DNA-binding patterns of homo and heteromeric MTFs with PHYLOY are shown using electrophoretic mobility shift assays, revealing broader interaction patterns between PHYLOY and MTFs that depend on highly conserved hydrophobic residues. Point mutations of these residues allowed gain or loss of interaction between MTFs and PHYLOY. Expressing PHYLOY under the control of the SEP3 and AP1 promoter in Arabidopsis further demonstrated whorl specific phenotypes, recapitulating the in vitro interaction and DNA-binding patterns. These findings reveal how PHYLOY targets J o u r n a l P r e -p r o o f specific MTFs through structural mimicry, resulting in impaired MTF tetramer formation and homeotic conversion of floral organs due to loss of active MTF tetramers.

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BibTeX RIS

BibTeX

@article{galien2026phytoplasma,
  title = {{The phytoplasma effector, Phyllogen, structurally mimics host plant MADS transcription factors}},
  author = {Antonin Galien and Stephanie Hutin and Sarah Le Hir and Michel Paul and Pascal Albanese and Sylvie Kieffer-Jaquinod and Audrey Guillotin and Nozomu Iwabuchi and Kensaku Maejima and Max H Nanao and Mark D Tully and Veronique Hugouvieux and Chloe Zubieta},
  journal = {Journal of Biological Chemistry},
  year = {2026},
  month = sep,
  doi = {10.1016/j.jbc.2026.113449},
  url = {https://hal.science/hal-05741051v1},
  note = {CC BY-NC-ND 4.0},
}

RIS

TY  - JOUR
TI  - The phytoplasma effector, Phyllogen, structurally mimics host plant MADS transcription factors
AU  - Antonin Galien
AU  - Stephanie Hutin
AU  - Sarah Le Hir
AU  - Michel Paul
AU  - Pascal Albanese
AU  - Sylvie Kieffer-Jaquinod
AU  - Audrey Guillotin
AU  - Nozomu Iwabuchi
AU  - Kensaku Maejima
AU  - Max H Nanao
AU  - Mark D Tully
AU  - Veronique Hugouvieux
AU  - Chloe Zubieta
PY  - 2026
DA  - 2026/09/07
JO  - Journal of Biological Chemistry
DO  - 10.1016/j.jbc.2026.113449
UR  - https://hal.science/hal-05741051v1
AB  - Phytoplasmas are obligate plant pathogens that include species causing severe developmental abnormalities in diverse plant families. Phytoplasma infections may result in dwarfism, witches' broom, virescence and phyllody, the conversion of reproductive organs into leaf-like structures. Phyllody is due to the activity of phytoplasma effector proteins, called phyllogens, that interact with the host MADS transcription factor (MTF) network. This interaction was believed to be specific for members of the AP1/SEP/AGL6 superclade of tetrameric MTFs, key regulators of floral meristem identity and organogenesis. Here, we determined the molecular and atomic basis for the interaction between the phyllogen from Onions Yellow phytoplasma (PHYLOY) and the floral MTFs, APETALA1, SEPALLATA and AGAMOUS using biochemical, structural and genetic experiments. The DNA-binding patterns of homo and heteromeric MTFs with PHYLOY are shown using electrophoretic mobility shift assays, revealing broader interaction patterns between PHYLOY and MTFs that depend on highly conserved hydrophobic residues. Point mutations of these residues allowed gain or loss of interaction between MTFs and PHYLOY. Expressing PHYLOY under the control of the SEP3 and AP1 promoter in Arabidopsis further demonstrated whorl specific phenotypes, recapitulating the in vitro interaction and DNA-binding patterns. These findings reveal how PHYLOY targets J o u r n a l P r e -p r o o f specific MTFs through structural mimicry, resulting in impaired MTF tetramer formation and homeotic conversion of floral organs due to loss of active MTF tetramers.
SN  - 0021-9258
SN  - 1083-351X
ER  -

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