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- Title
The auxintransport inhibitor response 3(tir3) allele ofBIGand auxin transport inhibitors affect the gibberellin status of Arabidopsis.
- Authors
Desgagné-Penix, Isabel; Eakanunkul, Suntara; Coles, Jeremy P.; Phillips, Andrew L.; Hedden, Peter; Sponsel, Valerie M.
- Abstract
The Arabidopsis geneBIG(formerlyDOC1/TIR3/UMB1/ASA1) is known to encode a huge calossin-like protein that is required for polar auxin transport (PAT). Mutations at this locus, in addition to reducing PAT, can alter the sensitivity of plants to several hormones and light. Thetir3-1allele ofBIGreduces the response of plants to application of the gibberellin (GA) precursorsent-kaurenoic acid and GA12 and its semidwarf phenotype is partially reversed by C19-GAs. The effects of auxin transport inhibitors (ATIs) on GA 20-oxidation was examined in wild-type andtir3-1seedlings. 1-N-naphthylphthalamic acid (NPA) and triiodobenzoic acid lead to overexpression of the GA-biosynthetic geneAtGA20ox1comparable in magnitude to the overexpression observed in seedlings treated with paclobutrazol, a GA biosynthesis inhibitor. In contrast to that ofAtGA20ox1, overexpression ofAtGA20ox2is pronounced only in paclobutrazol-treated Col and Ler, and is less intir3-1and in all NPA-treated seedlings. Thus the effects ofBIGand ATIs on the expression of genes encoding GA 20-oxidases are complex, and suggest that at least in some tissues ATIs, directly or indirectly, may reduce the level of bioactive GA and/or alter GA signal transduction.
- Subjects
GIBBERELLINS; PLANT hormones; ARABIDOPSIS; SEEDLINGS; BIOCHEMICAL engineering; BIOCHEMISTRY
- Publication
Plant Journal, 2005, Vol 41, Issue 2, p231
- ISSN
0960-7412
- Publication type
Article
- DOI
10.1111/j.1365-313X.2004.02287.x