Mutants auxin-resistant

Chemical Genetics, Target Site Identification, Resistant Mutants, Herbicide Mode of Action, Auxins, Arahidopsis... 

Our auxin-resistant A. plumbaginifolia mutants add to the small collection of mutations that have been described during the last few years in tobacco [16] and in Arabidopsis [9], which define at least two and perhaps up to four genes involved in responses to applied auxin. The tobacco, Arabidopsis and N. plumbaginifolia mutants resemble each other in having disturbed root growth characteristics. No complete biochemical explanation of the auxin resistance of any of these mutants has been established. 

Auxin mutants and cross resistance. Many hormone mutants, both in Arabidopsis and other species, display altered responses to more than one plant hormone [47]. In... 

Useful progress has been made in the genetics of GAs, ABA and, more recently, ethylene [11]. However, relatively few mutations have been reported involving auxins or cytokinins. Both recessive and dominant mutants have been isolated with increased resistance to synthetic auxins [8, 14, 16], and two mutants have been described with significantly altered levels of lAA or lAA conjugates [20, 22]. Mutations have been reported that affect the cytokinin requirement of tobacco leaf cells in culture [15], and cytokinin resistance and production in the moss Phys-comitrella patens [23]. 

In our laboratory we have been using M2 seed families and mutagenized haploid protoplasts of Nicotianaplumbaginifolia in a combined approach to search both for mutants resistant to toxic concentrations of auxins and cytokinins, and for temperature-sensitive auxin auxotrophs. The hope has been that variation isolated using these rather unspecific selection procedures would include mutations in hormone uptake, biosynthesis, catabolism and reception. The isolation methods, particularly for the cloning of auxotrophs, are laborious, and during the last five years we have slowly assembled a small collection of mutants which we feel will allow us to test several current theories about auxin and cytokinin synthesis and mode of action. This paper briefly reviews our work on the mutants and their characterization. 

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