Table I.

GC-MS analysis Identification of 26-hydroxylated metabolites converted from BL, [2H6]BL, CS, and [2H6]CS in transformed yeast cultures and Arabidopsis seedlings. Yeast were transformed with pED8, which contains the CYP72B1 open reading frame under the control of a Gal-inducible promoter. Arabidopsis seedlings tested were the wild type (Ws-2), a CYP72B1 null (cyp72b1-1), and a CYP72B1 overexpressor (cyp72b1—ox8). All experimental replicates = 1 n.

Yeast Arabidopsis Seedlings
Compound Retention Time Characteristic Ions m/z (with Relative Intensities) cyp72b1-1 Ws-2 cyp72b1-ox8
min μg 26-OH brassinosteroid detected
26-OHBL standard 13.72 736 [M+] (5), 721 (7), 619 (17), 577 (14), 564 (13), 299 (25), 156 (100)
BL metabolite 13.72 736 [M+] (4), 721 (6), 619 (17), 577 (15), 564 (14), 299 (27), 156 (100) 0.15 1.2 2.2
[2H6] BL metabolite 13.70 742 [M+] (4), 727 (6), 625 (16), 583 (13), 570 (12), 299 (25), 156 (100) 0.08 1.4 2.4
26-OHCS standard 12.25 720 [M+] (3), 705 (24), 603 (100), 514 (27)
CS metabolite 12.25 720 [M+] (3), 705 (23), 603 (100), 514 (29) 0.05 0.4 1.7
[2H6] CS metabolite 12.23 726 [M+] (2), 711 (23), 609 (100), 520 (27) 0.01 0.4 1.5