Sci. STKE, 18 February 2003
Plant Biology Auxin Enhances Root Growth
Root growth is stimulated by plant hormones, such as gibberellin. Gibberellin opposes the action of nuclear-localized DELLA proteins that repress growth. RGA is one such DELLA protein. Fu and Harberd report that Arabidopsis mutants deficient for gibberellin (gal-3) had shorter roots than wild-type plants and that Arabidopsis triple mutants for gal-3 and two of the DELLA genes rga-24 and gai-t6 had normal root length. Giberrellin stimulated the translocation of a green fluorescent protein (GFP)-tagged RGA protein from the nucleus and destabilization of RGA. However, if the shoot apex was removed (so-called decapitated plants), the loss of GFP-RGA from the nucleus in response to giberrellin was delayed. Addition of auxin and giberrellin to the decapitated plants restored the rate of GFP-RGA nuclear export to that observed in intact plants. Additional experiments using auxin inhibitors or RNA interference to block synthesis of the auxin transporter supported the role for auxin in promoting the gibberellin-induced nuclear export and destabilization of RGA. Thus, auxin and gibberellin signaling both contribute to controlling the rate of root growth.
X. Fu, N. P. Harberd, Auxin promotes Arabidopsis root growth by modulating gibberellin response. Nature 421, 740-743 (2003). [Online Journal]
Citation: Auxin Enhances Root Growth. Sci. STKE 2003, tw72 (2003).
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