Auxin receptor gene

B. Phylogenetic tree of TIRl auxin receptor gene family in Arahidopsis. 

Among the most noticeable findings from the research on plant hormones, the identification of receptors and receptor genes must be emphasized. In the last decade, since the publication of the previous edition of the book Comprehensive Natural Products Chemistry,5 the receptors and the receptor genes for ethylene, BRs, cytokinins, auxins, GAs, and abscisic acid have been identified, as described in the section for each plant hormone. 

D-treated cells transcribed the mRNAs complementary to the seven cDNA clones only nuclei from water treated-cells gave no hybridization signal [17]. Therefore, these nuclei provide an excellent system with which transacting factors that may play a role in auxin-induced gene expression can be analyzed (i.e. the soluble auxin receptor [10, 15]). 

The next step in the perception-transduction mechanism of auxin should be more specific. We plan to use the reinitiating nuclei from tobacco in reconstitution experiments with partially purified auxin-binding protein. We have shown in vivo that several genes are specifically induced by auxin. We hope to be able to show the same induction in vitro by addition of auxin-receptor complex to nuclei isolated from auxin-starved cells, where these genes are normally not expressed. 

Note added in proof Data on antibody blockade of the protoplast auxin response have now been published [24]. Furthermore, Shimomura reports on receptor gene cloning [25]. 

There are three major classes of synthetic auxins the aryl acetic acids, which include indoleacetic acid (lAA) itself (Fig. 1 structure 2-1) and 1-naphthyl acetic acid (2-4), phenoxy acetic acids, represented by 2,4-dichlorophenoxy acetic acid (2,4-D) (2-7) and the benzoic acids, e.g. 2,3,6-trichloro benzoic acid (2-9). It remains the case however, that there is no stmcture-activity proposal which satisfactorily covers all molecules which are known to have auxin activity. As is well known, auxins have multiple effects, including promotion of cell elongation, cell division and gene expression. There may well be different receptors for each effect, and differences between receptors. An auxin binding protein (ABP), has now been characterised, and is possibly a receptor controlling cell elongation [3]. 

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