title: How do Arabidopsis roots differentiate hydrotropism from gravitropism?
abstract: Root hydrotropism is a response to moisture gradients, which is considered to be important for drought avoidance. Recent reevaluation of root hydrotropism has emphasised the dominating effect of root gravitropism on it. It has been suggested that amyloplast dynamics inside columella cells and auxin regulation play roles in this interacting mechanism, even though the existence of distinct pathways of two tropisms derived from different stimuli remained unclear. We have recently found two factors that separate the mechanism of hydrotropism from that of gravitropism in Arabidopsis seedling roots. One is the difference in the mode of auxin-mediated growth regulation between two tropisms, and the other is the identification of gene indispensable only for root hydrotropism. Here we summarize the recent progress on root hydrotropism research and discuss the remaining and emerging issues.
authors.affiliation: Graduate School of Life Sciences, Tohoku University.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Miyazawa
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Takahashi
references.citation: Science. 1985 Oct 25;230(4724):445-7
references.pmid: 17816077
references.citation: Plant Physiol. 2003 Jun;132(2):805-10
references.pmid: 12805610
references.citation: Plant Physiol. 2003 Feb;131(2):536-46
references.pmid: 12586878
references.citation: Protoplasma. 2006 Dec;229(2-4):175-81
references.pmid: 17180499
references.citation: J Plant Res. 1996 Sep;109(1095):335-7
references.pmid: 11539859
references.citation: Plant Cell Physiol. 2002 Jul;43(7):793-801
references.pmid: 12154142
references.citation: J Plant Res. 1997 Jun;110(1098):163-9
references.pmid: 11541137
references.citation: Trends Plant Sci. 2005 Jan;10(1):44-50
references.pmid: 15642523
references.citation: Planta. 2002 Dec;216(2):203-11
references.pmid: 12447533
references.citation: Proc Natl Acad Sci U S A. 2007 Mar 13;104(11):4724-9
references.pmid: 17360591
references.citation: J Exp Bot. 2007;58(5):1143-50
references.pmid: 17244629