A gamma-thionin protein from apple, MdD1, is required for defence against S-RNase-induced inhibition of pollen tube prior to self/non-self recognition

Zhaoyu Gu, Wei Li, James Doughty, Dong Meng, Qing Yang, Hui Yuan, Yang Li, Qiuju Chen, Jie Yu, Chun sheng Liu, Tianzhong Li

Research output: Contribution to journalArticle


Apple exhibits S-RNase-mediated self-incompatibility. Although the cytotoxic effect of S-RNase inside the self-pollen tube has been studied extensively, the underlying defence mechanism in pollen tube in Rosaceae remains unclear. On exposure to stylar S-RNase, plant defence responses are activated in the pollen tube; however, how these are regulated is currently poorly understood. Here, we show that entry of both self and non-self S-RNase into pollen tubes of apple (Malus domestica) stimulates jasmonic acid (JA) production, in turn inducing the accumulation of MdMYC2 transcripts, a transcription factor in the JA signalling pathway widely considered to be involved in plant defence processes. MdMYC2 acts as a positive regulator in the pollen tube activating expression of MdD1, a gene encoding a defence protein. Importantly, MdD1 was shown to bind to the RNase activity sites of S-RNase leading to inhibition of enzymatic activity. This work provides intriguing insights into an ancient defence mechanism present in apple pollen tubes where MdD1 likely acts as a primary line of defence to inhibit S-RNase cytotoxicity prior to self/non-self recognition.

Original languageEnglish
Pages (from-to)2184-2198
Number of pages15
JournalPlant Biotechnology Journal
Issue number11
Early online date18 Apr 2019
Publication statusPublished - 1 Nov 2019


  • Malus domestica
  • MdD1
  • plant defence
  • pollen tube growth
  • S-RNase

ASJC Scopus subject areas

  • Biotechnology
  • Agronomy and Crop Science
  • Plant Science

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