Plant Hormones

(Hypo)Nasty Plant Mutation

Science's STKE  16 Jan 2001:
Vol. 2001, Issue 65, pp. tw1
DOI: 10.1126/stke.2001.65.tw1

A mutation in Arabidopsis may help reveal a role for double-stranded RNA binding proteins in mediating signals from multiple plant hormones. Lack of function of the HYPONASTIC (meaning movement bending the leaves inward and upward) LEAVES protein (HYL1) leads to a pleiotropic phenotype including decreased response to gravistimulation and reduced apical dominance that appears to reflect altered response to internal and external stimuli. Indeed, Lu and Federoff show that in hyl1 mutants, responses to the hormones auxin and cytokinin is blunted, whereas plants are hypersensitive to abscisic acid. The HYL1 gene was cloned and encodes a protein with two double-stranded RNA-binding motifs similar to those in human interferon-induced RNA-dependent protein kinse P68. The protein contains a nuclear localization sequence and is concentrated in nuclei. Although the mechanism by which HYL1 contributes to hormonal signaling is not yet clear, the authors propose several interesting possibilities including function as a transcriptional coactivator or corepressor, or control of transcript stability.

C. Lu, N. Fedoroff, A mutation in the Arabidopsis HYL1 gene encoding a dsRNA binding protein affects responses to abscisic acid, auxin, and cytokinin. Plant Cell 12, 2351-2365 (2001). [Abstract] [Full Text]