A Phytophthora effector promotes homodimerization of host transcription factor StKNOX3 to enhance susceptibility

Jing Zhou, Yetong Qi, Jiahui Nie, Lei Guo, Ming Luo, Hazel McLellan, Petra C. Boevink, Paul R. J. Birch, Zhendong Tian (Lead / Corresponding author)

Research output: Contribution to journalArticlepeer-review


Oomycete pathogens secrete hundreds of cytoplasmic RxLR effectors to modulate host immunity by targeting diverse plant proteins. Revealing how effectors manipulate host proteins is pivotal to understand infection processes and to develop new strategies to control plant disease. Here we show that the Phytophthora infestans RxLR effector Pi22798 interacts in the nucleus with a potato class II knotted-like homeobox (KNOX) transcription factor, StKNOX3. Silencing the orthologue NbKNOX3 in Nicotiana benthamiana reduces host colonization by P. infestans, whereas transient and stable overexpression of StKNOX3 enhances infection. StKNOX3 forms a homodimer which is dependent on its KNOX II domain. The KNOX II domain is also essential for Pi22798 interaction and for StKNOX3 to enhance P. infestans colonization, indicating that StKNOX3 homodimerization contributes to susceptibility. However, critically, the effector Pi22798 promotes StKNOX3 homodimerization, rather than heterodimerization to another KNOX transcription factor StKNOX7. These results demonstrate that the Oomycete effector Pi22798 increases pathogenicity by promoting homodimerization specifically of StKNOX3 to enhance susceptibility.

Original languageEnglish
JournalJournal of Experimental Botany
Early online date11 Jul 2022
Publication statusE-pub ahead of print - 11 Jul 2022


  • Potato late blight
  • Effector
  • Pathogenicity
  • Homodimerization
  • Class II knotted-like homeobox (KNOX) transcription factor
  • Plant immunity


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