Chemical control of xylem differentiation by thermospermine, xylemin and auxin

• Published in: Scientific reports Vol. 6; no. 1; p. 21487
• Main Authors: Yoshimoto, Kaori, Takamura, Hiroyoshi, Kadota, Isao, Motose, Hiroyasu, Takahashi, Taku
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 16-02-2016; Nature Publishing Group
• Subjects: 13; 2,4-Dichlorophenoxyacetic Acid - analogs & derivatives; 2,4-Dichlorophenoxyacetic Acid - pharmacology; 38; 38/77; 42; 631/449/1741; 631/449/2491; 631/449/2653; 64; Angiosperms; Arabidopsis; Arabidopsis Proteins - biosynthesis; Arabidopsis Proteins - drug effects; Biomass; Biosynthesis; Cell Differentiation - drug effects; Chemical control; Deficient mutant; Gene expression; Genetic engineering; Humanities and Social Sciences; Hydrolysis; Indoleacetic Acids - pharmacology; Mechanical properties; Minerals; Morphology; multidisciplinary; Plant species; Polyamines; Putrescine - analogs & derivatives; Putrescine - pharmacology; Science; Seedlings; Spermidine; Spermidine - antagonists & inhibitors; Spermidine - metabolism; Spermine; Spermine - analogs & derivatives; Spermine - biosynthesis; Xylem; Xylem - drug effects; Xylem - physiology
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep21487

The xylem conducts water and minerals from the root to the shoot and provides mechanical strength to the plant body. The vascular precursor cells of the procambium differentiate to form continuous vascular strands, from which xylem and phloem cells are generated in the proper spatiotemporal pattern. Procambium formation and xylem differentiation are directed by auxin. In angiosperms, thermospermine, a structural isomer of spermine, suppresses xylem differentiation by limiting auxin signalling. However, the process of auxin-inducible xylem differentiation has not been fully elucidated and remains difficult to manipulate. Here, we found that an antagonist of spermidine can act as an inhibitor of thermospermine biosynthesis and results in excessive xylem differentiation, which is a phenocopy of a thermospermine-deficient mutant
acaulis5
in
Arabidopsis thaliana
. We named this compound xylemin owing to its xylem-inducing effect. Application of a combination of xylemin and thermospermine to wild-type seedlings negates the effect of xylemin, whereas co-treatment with xylemin and a synthetic proauxin, which undergoes hydrolysis to release active auxin, has a synergistic inductive effect on xylem differentiation. Thus, xylemin may serve as a useful transformative chemical tool not only for the study of thermospermine function in various plant species but also for the control of xylem induction and woody biomass production.