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
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
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DOI：
10.1046/j.1365-313x.1999.00454.x
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发表时间：
1999-05-01
期刊：
影响因子：
7.2
通讯作者：
Barbier-Brygoo, H
中科院分区：
文献类型：
--
作者：
Ephritikhine, G;Fellner, M;Barbier-Brygoo, H
利用拟南芥的遗传学方法旨在鉴定影响生长素信号传导的事件的突变，通常导致生长素抗性突变体的分离。从一个选择屏幕专门开发的分离生长素过敏突变体，一个突变株系选择其增加的敏感性生长素（x 2至3）的根伸长反应。对sax 1（对脱落酸和生长素过敏）的遗传分析表明，突变体表型分离为一个隐性孟德尔位点，定位于1号染色体的下臂。Sax 1幼苗在体外生长表现出短卷曲的主根和小，圆，深绿色的子叶。在温室中，成年纱丽植物的特点是矮化表型，发育延迟和生育力下降。纱丽幼苗的进一步生理特性表明，最显着的特点是一个大的增加（x 40）ABA敏感性的根伸长，并在较小程度上，ABA诱导的气孔关闭;在其他方面，下胚轴伸长是耐赤霉素和乙烯。这些变化的激素敏感性纱丽植物共分离的矮化表型，表明参与细胞伸长的过程被修改。用外源油菜素类固醇处理突变体幼苗部分挽救了野生型的大小，这表明油菜素类固醇的生物合成可能会受到影响纱丽植物。野生型阿坝，生长素和赤霉素的敏感性也恢复在sax 1植物通过外源性应用油菜素类固醇，说明BR相关的SAX 1基因的关键重要性。
Genetic approaches using Arabidopsis thaliana aimed at the identification of mutations affecting events involved in auxin signalling have usually led to the isolation of auxin-resistant mutants. From a selection screen specifically developed to isolate auxin-hypersensitive mutants, one mutant line was selected for its increased sensitivity to auxin (x 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 sari plants were characterized by a dwarf phenotype, delayed development and reduced fertility. Further physiological characterization of sari seedlings revealed that the most striking trait was a large increase (x 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 sari 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 sari plants. Wild-type sensitivities to ABA, auxin and gibberellins were also restored in sax1 plants by exogenous application of brassinosteroid, illustrating the pivotal importance of the BR-related SAX1 gene.