Growth and Vegetative Development
Crawford, Scott , Leyser, Ottoline .
Shoot branching and the MAX pathway in Arabidopsis.
The Arabidopsis max (more axillary growth) mutants exhibit greatly increased shoot branching. Wild-type root stocks when grafted to mutant shoots exhibit a restoration of the wild-type branching pattern. This suggests that the mutant plants lack an upwardly mobile, graft transmissible inhibitory factor of shoot branching. This signal is not auxin or cytokinin as the auxin level in mutant plants is that of wild-type plants and the level of cytokinin is reduced. This gives strong support to the notion of a novel plant hormone involved in the inhibition of axillary shoot branching. Four loci have been identified; MAX1-MAX4. Recessive mutations at these loci all confer a bushy phenotype. The max mutants have all been well characterised and define genes which are suspected to act in the same pathway to regulate axillary meristem branching. Recent research in our laboratory has shown that the MAX pathway acts to regulate auxin transport capacity in the stem through the abundance of the PIN auxin efflux carrier proteins. Since the ability of buds to grow is tightly regulated with their ability to export auxin, it has been suggested that the MAX pathway regulates shoot branching by effectively blocking auxin export from the bud by limiting the capacity for auxin movement in the main stem.
This project aims to further test the auxin transport model for the MAX pathway; elucidate the mechanism by which the MAX dependant signal acts to influence PIN expression; and to understand how changes in PIN expression and localisation affect axillary bud outgrowth. Experimental data and a discussion of results will be presented.
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1 - University of York, Department of Biology, PO Box 373, York, North Yorks, YO10 5YW, United Kingdom
2 - University of York, Department of Biology
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM