| 16367964 |
Nakamura A, Nakajima N, Goda H, Shimada Y, Hayashi K, Nozaki H, Asami T, Yoshida S, Fujioka S: Arabidopsis Aux/IAA genes are involved in brassinosteroid-mediated growth responses in a manner dependent on organ type. Plant J. 2006 Jan;45(2):193-205.
We examined whether auxin/indole-3-acetic acid (Aux/IAA) proteins, which are key players in auxin-signal transduction, are involved in brassinosteroid (BR) responses. iaa7/axr2-1 and iaa17/axr3-3 mutants showed aberrant BR sensitivity and aberrant BR-induced gene expression in an organ-dependent manner. Two auxin inhibitors were tested in terms of BR responses. Yokonolide B inhibited BR responses, whereas p-chlorophenoxyisobutyric acid did not inhibit BR responses. DNA microarray analysis revealed that 108 genes were up-regulated, while only eight genes were down-regulated in iaa7. Among the genes that were up- or down-regulated in axr2, 22% were brassinolide-inducible genes, 20% were auxin-inducible genes, and the majority were sensitive neither to BR nor to auxin. An inhibitor of BR biosynthesis, brassinazole, inhibited auxin induction of the DR5-GUS gene, which consists of a synthetic auxin-response element, a minimum promoter, and a beta-glucuronidase. These results suggest that Aux/IAA proteins function in auxin- and BR-signaling pathways, and that IAA proteins function as the signaling components modulating BR sensitivity in a manner dependent on organ type. |
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