Thermospermine suppresses auxin-inducible xylem differentiation in Arabidopsis thaliana |
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Authors: | Kaori Yoshimoto Yoshiteru Noutoshi Ken-ichiro Hayashi Ken Shirasu Taku Takahashi Hiroyasu Motose |
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Affiliation: | 1.Division of Bioscience; Graduate School of Natural Science and Technology; Okayama University; Okayama, Japan;2.Research Core for Interdisciplinary Sciences; Okayama University; Okayama, Japan;3.Department of Biochemistry; Okayama University of Science; Okayama, Japan;4.Plant Science Center; RIKEN; Yokohama, Kanagawa, Japan |
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Abstract: | 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 xylem-inducing 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. |
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Keywords: | thermospermine auxin 2 4-D xylem differentiation ACAULIS5 chemical biology |
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