The AT-hook protein AHL29 promotes Bacillus subtilis colonization by suppressing SWEET2-mediated sugar retrieval in Arabidopsis roots

Yun Chien Wu, Chien Wen Yu, Jo Yu Chiu, Yu Hsuan Chiang, Nobutaka Mitsuda, Xu Chen Yen, Tzu Pi Huang, Tzu Fang Chang, Cen Jie Yen, Woei Jiun Guo

Research output: Contribution to journalArticlepeer-review

Abstract

Beneficial Bacillus subtilis (BS) symbiosis could combat root pathogenesis, but it relies on root-secreted sugars. Understanding the molecular control of sugar flux during colonization would benefit biocontrol applications. The SWEET (Sugar Will Eventually Be Exported Transporter) uniporter regulates microbe-induced sugar secretion from roots; thus, its homologs may modulate sugar distribution upon BS colonization. Quantitative polymerase chain reaction revealed that gene transcripts of SWEET2, but not SWEET16 and 17, were significantly induced in seedling roots after 12 h of BS inoculation. Particularly, SWEET2-β-glucuronidase fusion proteins accumulated in the apical mature zone where BS abundantly colonized. Yet, enhanced BS colonization in sweet2 mutant roots suggested a specific role for SWEET2 to constrain BS propagation, probably by limiting hexose secretion. By employing yeast one-hybrid screening and ectopic expression in Arabidopsis protoplasts, the transcription factor AHL29 was identified to function as a repressor of SWEET2 expression through the AT-hook motif. Repression occurred despite immunity signals. Additionally, enhanced SWEET2 expression and reduced colonies were specifically detected in roots of BS-colonized ahl29 mutant. Taken together, we propose that BS colonization may activate repression of AHL29 on SWEET2 transcription that would be enhanced by immunity signals, thereby maintaining adequate sugar secretion for a beneficial Bacillus association.

Original languageEnglish
Pages (from-to)1084-1098
Number of pages15
JournalPlant, Cell and Environment
Volume47
Issue number4
DOIs
Publication statusPublished - 2024 Apr

All Science Journal Classification (ASJC) codes

  • Physiology
  • Plant Science

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