000			02636nam a22002897a 4500
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008			250225b |||||||| |||| 00| 0 eng d
022			_a0176-1617
040			_aMSU _bEnglish _cMSU _erda
050	0	0	_aQK711.2 JOU
100	1		_aDümmer, Michaela _eauthor
245	1	0	_aGravitropism in Arabidopsis thaliana: Root-specific action of the EHB gene and violation of the resultant law _ccreated by Michaela Dümmer, Christoph Forreiter and Paul Galland
264	1		_aAmsterdam: _bElsevier GmbH, _c2015.
336			_2rdacontent _atext _btxt
337			_2rdamedia _aunmediated _bn
338			_2rdacarrier _avolume _bnc
440			_aJournal of plant physiology _vVolume 189
520	3		_aGravitropic bending of seedlings of Arabidopsis thaliana in response to centrifugal accelerations was determined in a range between 0.0025 and 4 × g to revisit and validate the so-called resultant law, which claims that centrifugation causes gravitropic organs to orient parallel to the resultant stimulus vector. We show here for seedlings of A. thaliana that this empirical law holds for hypocotyls but surprisingly fails for roots. While the behavior of hypocotyls could be modeled by an arc tangent function predicted by the resultant law, roots displayed a sharp maximum at 1.8 × g that substantially overshoots the predicted value and that represents a novel phenomenon, diagravitropism elicited by centrifugal acceleration. The gravitropic bending critically depended on the orientation of the seedling relative to the centrifugal acceleration. If the centrifugal vector pointed toward the cotyledons, gravitropic bending of hypocotyls and roots was substantially enhanced. The complex behavior of Arabidopsis seedlings provides strong evidence that gravitropic bending entails a cosine component (longitudinal stimulus) to which the seedlings were more sensitive than to the classical sine component. The absolute gravitropic thresholds of hypocotyls and roots were determined in a clinostat-centrifuge and found to be below 0.015 × g. A tropism mutant lacking the EHB1 protein, which interacts with ARF-GAP (ARF GTPase-activating protein) and thus indirectly with a small ARF-type G protein, displayed a lower gravitropic threshold for roots and also enhanced bending, while the responses of the hypocotyls remained nearly unaffected.
650			_aArabidopsis
650			_aCentrifugation
650			_aClinostatting
700	1		_aForreiter, Christoph _eco-author
700			_aGalland, Paul _eco-author
856			_uhttps://doi.org/10.1016/j.jplph.2015.09.008
942			_2lcc _cJA
999			_c169028 _d169028