The sax1 dwarf mutant of Arabidopsis thaliana shows altered sensitivity of growth responses to abscisic acid, auxin, gibberellins and ethylene and is partially rescued by exogenous brassinosteroid

Autor: Geneviève Ephritikhine, Candida Vannini, Martin Fellner, Hélène Barbier-Brygoo, Danielle Lapous
Rok vydání: 1999
Předmět:
Zdroj: The Plant Journal. 18:303-314
ISSN: 0960-7412
DOI: 10.1046/j.1365-313x.1999.00454.x
Popis: Summary Genetic approaches using Arabidopsis thaliana aimed at the identification of mutations affecting events involved in auxin signalling have usually led to the isolation of auxinresistant mutants. From a selection screen specifically developed to isolate auxin-hypersensitive mutants, one mutant line was selected for its increased sensitivity to auxin (H 2 to 3) for the root elongation response. The genetic analysis of sax1 (hypersensitive to abscisic acid and auxin) indicated that the mutant phenotype segregates as a single recessive Mendelian locus, mapping to the lower arm of chromosome 1. Sax1 seedlings grown in vitro showed a short curled primary root and small, round, dark-green cotyledons. In the greenhouse, adult sax1 plants were characterized by a dwarf phenotype, delayed development and reduced fertility. Further physiological characterization of sax1 seedlings revealed that the most striking trait was a large increase (3 40) in ABA-sensitivity of root elongation and, to a lesser extent, of ABA-induced stomatal closure; in other respects, hypocotyl elongation was resistant to gibberellins and ethylene. These alterations in hormone sensitivity in sax1 plants co-segregated with the dwarf phenotype suggesting that processes involved in cell elongation are modified. Treatment of mutant seedlings with an exogenous brassinosteroid partially rescued a wild-type size, suggesting that brassinosteroid biosynthesis might be affected in sax1
Databáze: OpenAIRE
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