Thermospermine suppresses auxin-inducible xylem differentiation in Arabidopsis thaliana

Kaori Yoshimoto, Yoshiteru Noutoshi, Ken ichiro Hayashi, Ken Shirasu, Taku Takahashi, Hiroyasu Motose

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


Thermospermine, a structural isomer of spermine, is synthesized by a thermospermine synthase designated ACAULIS5 (ACL5). Thermospermine-deficient acl5 mutant of Arabidopsis thaliana shows severe dwarfism and excessive xylem differentiation. By screening for compounds that affect xylem differentiation in the acl5 mutant, we identified auxin analogs that remarkably enhanced xylem vessel differentiation in the acl5 mutant but not in the wild type. The xyleminducing effect of auxin analogs was clearly suppressed by thermospermine, indicating that auxin-inducible xylem differentiation is normally limited by thermospermine. Here, we further characterized xylem-inducing effect of auxin analogs in various organs. Auxin analogs promoted protoxylem differentiation in roots and cotyledons in the acl5 mutant. Our results indicate that the opposite action between thermospermine and auxin in xylem differentiation is common in different organs and also suggest that thermospermine might be required for the suppression of protoxylem differentiation.

Original languageEnglish
JournalPlant Signaling and Behavior
Issue number8
Publication statusPublished - Aug 2012


  • 2,4-D
  • Auxin
  • Chemical biology
  • Thermospermine
  • Xylem differentiation

ASJC Scopus subject areas

  • Plant Science


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