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Mutations in Arabidopsis thaliana genes involved in the tryptophan biosynthesis pathway affect root waving on tilted agar surfaces

Author:
Rutherford, R., Gallois, P., Masson, P.H.
Source:
The plant journal 1998 v.16 no.2 pp. 145-154
ISSN:
0960-7412
Subject:
Arabidopsis thaliana, mutants, tryptophan, amino acid metabolism, genes, roots, root systems, agarose, growing media, aminobenzoic acids, seedlings, shoots, oxo-acid-lyases, hydro-lyases, mutation, phenotype, indole acetic acid
Abstract:
Arabidopsis thaliana roots grow in a wavy pattern upon a slanted surface. A novel mutation in the anthranilate synthase alpha 1 (ASA1) gene, named trp5-2(wvc1), and mutations in the tryptophan synthase alpha and beta 1 genes (trp3-1 and trp2-1, respectively) confer a compressed root wave phenotype on tilted agar surfaces. When trp5-2(wvc1) seedlings are grown on media supplemented with anthranilate metabolites, their roots wave like wild type. Genetic and pharmacological experiments argue that the compressed root wave phenotypes of trp5-2(wvc1), trp2-1 and trp3-1 seedlings are not due to reduced IAA biosynthetic potential, but rather to a deficiency in L-tryptophan (L-Trp), or in a L-Trp derivative. Although the roots of 7-day-old seedlings possess higher concentrations of free L-Trp than the shoot as a whole, trp5-2(wvc1) mutants show no detectable alteration in L-Trp levels in either tissue type, suggesting that a very localized shortage of L-Trp, or of a L-Trp-derived compound, is responsible for the observed phenotype.
Agid:
1447739