Superroot, a recessive mutation in Arabidopsis, confers auxin overproduction.

Abstract

We have isolated seven allelic recessive Arabidopsis mutants, designated superroot (surl-7 to surl-7), displaying several abnormalities reminiscent of auxin effects. These characteristics include small and epinastic cotyledons, an elongated hypocotyl in which the connection between the stele and cortical and epidermal cells disintegrates, the development of excess adventitious and lateral roots, a reduced number of leaves, and the absence of an inflorescence. When germinated in the dark, surl mutants did not develop the apical hook characteristic of etiolated seedlings. We were able to phenocopy the Surl-phenotype by supplying auxin to wild-type seedlings, to propagate surl explants on phytohormonedeficient medium, and to regenerate shoots from these explants by the addition of cytokinins alone to the culture medium. Analysis by gas chromatography coupled to mass spectrometry indicated increased levels of both free and conjugated indole-3-acetic acid. surl was crossed to the mutant axr2 and the altered-auxin response mutant ctrl. The phenotype of both double mutants was additive. The surl gene was mapped on chromosome 2 at 0.5 centimorgans from the gene encoding phytochrome B.

Hybrid Weakness in Phaseolus vulgaris L. I. Disruption of Development and Hormonal Allocation

“…In addition, the fact that the dose responses for cytokinins are variable is consistent with the idea that plant responses to hormones are governed by more than one factor (Nissen 1988). For example, the presence of adventitious roots may be an indication that stem auxins are increasing (Boerjan et al 1995, Liu et al 1993). There are many reports of interactions between cytokinins and auxins, and some of the cytokinins such as zeatin and iso-pentenyladenine have been shown to influence auxin transport (Atzmon et al 1996).…”

Alfin1 transcription factor overexpression enhances plant root growth under normal and saline conditions and improves salt tolerance in alfalfa

“…Quantitative manipulation of root growth in plants has been dicult because of our lack of understanding of mechanisms that regulate root development and gene expression (Hauser et al 1995;Schiefelbein et al 1997) and has been compounded by the recessive nature of some of the mutations that enhance root growth (Boerjan et al 1995). Al®n1 appears to be a transcription factor that is predominantly expressed in roots and has been a potential candidate for regulation of gene expression in roots (Bastola et al 1998;Winicov and Bastola 1999).…”

“…Several root developmental mutants have been characterized (Hauser et al 1995;Schiefelbein et al 1997) and root-speci®c metabolites have been widely exploited (Flores et al 1999), but root-speci®c transcription factors for enhanced growth have remained largely unidenti®ed. It has been shown that meristem maintenance and proliferative growth of roots is determined by cell-cycle regulation and cyclin expression (Doerner et al 1996), and plant hormones such as ethylene and auxin can enhance root growth (Boerjan et al 1995), but speci®c regulatory factors are evidently also necessary for robust root growth.…”

Differential Hypocotyl and Root Development of Arabidopsis Auxin-Insensitive Mutants

“…In addition, promotion of the rate of cell division by BRs has been observed in some cases (Nakajima et al 1996, Clouse andSasse 1998). Higher meristematic activity in the axr2-7 root was also evidenced in enhanced lateral root formation, reported by several authors (Boerjan et al 1995, Knee and Hangarter 1996, Nagpal et a/. 2000.…”