PLANT PHYSIOLOGY , Vol 102, Issue 4 1203-1210, Copyright © 1993 by American Society of Plant Biologists

DEVELOPMENT AND GROWTH REGULATION

The Role of the Distal Elongation Zone in the Response of Maize Roots to Auxin and Gravity

H. Ishikawa and M. L. Evans
Department of Plant Biology, Ohio State University, Columbus, Ohio 43210-1293

We used a video digitizer system to (a) measure changes in the pattern of longitudinal surface extension in primary roots of maize (Zea mays L.) upon application and withdrawal of auxin and (b) compare these patterns during gravitropism in control roots and roots pretreated with auxin. Special attention was paid to the distal elongation zone (DEZ), arbitrarily defined as the region between the meristem and the point within the elongation zone at which the rate of elongation reaches 0.3 of the peak rate. For roots in aqueous solution, the basal limit of the DEZ is about 2.5 mm behind the tip of the root cap. Auxin suppressed elongation throughout the elongation zone, but, after 1 to 3 h, elongation resumed, primarily as a result of induction of rapid elongation in the DEZ. Withdrawal of auxin during the period of strong inhibition resulted in exceptionally rapid elongation attributable to the initiation of rapid elongation in the DEZ plus recovery in the main elongation zone. Gravistimulation of auxin-inhibited roots induced rapid elongation in the DEZ along the top of the root. This resulted in rapid gravitropism even though the elongation rate of the root was zero before gravistimulation. The results indicate that cells of the DEZ differ from cells in the bulk of the elongation zone with respect to auxin sensitivity and that DEZ cells play an important role in gravitropism.

This article has been cited by other articles:

				V. Kriechbaumer, W. J. Park, M. Piotrowski, R. B. Meeley, A. Gierl, and E. Glawischnig Maize nitrilases have a dual role in auxin homeostasis and -cyanoalanine hydrolysis J. Exp. Bot., December 1, 2007; 58(15-16): 4225 - 4233. [Abstract] [Full Text] [PDF]

				A. F. Rangel, I. M. Rao, and W. J. Horst Spatial aluminium sensitivity of root apices of two common bean (Phaseolus vulgaris L.) genotypes with contrasting aluminium resistance J. Exp. Bot., November 1, 2007; (2007) erm241v1. [Abstract] [Full Text] [PDF]

				V Poroyko, W. Spollen, L. Hejlek, A. Hernandez, M. LeNoble, G Davis, H. Nguyen, G. Springer, R. Sharp, and H. Bohnert Comparing regional transcript profiles from maize primary roots under well-watered and low water potential conditions J. Exp. Bot., January 1, 2007; 58(2): 279 - 289. [Abstract] [Full Text] [PDF]

				P. Illes, M. Schlicht, J. Pavlovkin, I. Lichtscheidl, F. Baluska, and M. Ovecka Aluminium toxicity in plants: internalization of aluminium into cells of the transition zone in Arabidopsis root apices related to changes in plasma membrane potential, endosomal behaviour, and nitric oxide production J. Exp. Bot., December 1, 2006; 57(15): 4201 - 4213. [Abstract] [Full Text] [PDF]

				R. ALONI, E. ALONI, M. LANGHANS, and C. I. ULLRICH Role of Cytokinin and Auxin in Shaping Root Architecture: Regulating Vascular Differentiation, Lateral Root Initiation, Root Apical Dominance and Root Gravitropism Ann. Bot., May 1, 2006; 97(5): 883 - 893. [Abstract] [Full Text] [PDF]

				I. Y. Perera, C.-Y. Hung, S. Brady, G. K. Muday, and W. F. Boss A Universal Role for Inositol 1,4,5-Trisphosphate-Mediated Signaling in Plant Gravitropism Plant Physiology, February 1, 2006; 140(2): 746 - 760. [Abstract] [Full Text] [PDF]

				L. Ge, H. Chen, J.-F. Jiang, Y. Zhao, M.-L. Xu, Y.-Y. Xu, K.-h. Tan, Z.-H. Xu, and K. Chong Overexpression of OsRAA1 Causes Pleiotropic Phenotypes in Transgenic Rice Plants, including Altered Leaf, Flower, and Root Development and Root Response to Gravity Plant Physiology, July 1, 2004; 135(3): 1502 - 1513. [Abstract] [Full Text] [PDF]

				G. Hou, D. R. Mohamalawari, and E. B. Blancaflor Enhanced Gravitropism of Roots with a Disrupted Cap Actin Cytoskeleton Plant Physiology, March 1, 2003; 131(3): 1360 - 1373. [Abstract] [Full Text] [PDF]

				Z. Ma, T. I. Baskin, K. M. Brown, and J. P. Lynch Regulation of Root Elongation under Phosphorus Stress Involves Changes in Ethylene Responsiveness Plant Physiology, March 1, 2003; 131(3): 1381 - 1390. [Abstract] [Full Text] [PDF]

				R. Swarup, J. Friml, A. Marchant, K. Ljung, G. Sandberg, K. Palme, and M. Bennett Localization of the auxin permease AUX1 suggests two functionally distinct hormone transport pathways operate in the Arabidopsis root apex Genes & Dev., October 15, 2001; 15(20): 2648 - 2653. [Abstract] [Full Text] [PDF]

				G. T.S. Beemster and T. I. Baskin STUNTED PLANT 1 Mediates Effects of Cytokinin, But Not of Auxin, on Cell Division and Expansion in the Root of Arabidopsis Plant Physiology, December 1, 2000; 124(4): 1718 - 1727. [Abstract] [Full Text]

				R. D. Firn, C. Wagstaff, and J. Digby The use of mutants to probe models of gravitropism J. Exp. Bot., August 1, 2000; 51(349): 1323 - 1340. [Abstract] [Full Text] [PDF]

				M. Kollmeier, H. H. Felle, and W. J. Horst Genotypical Differences in Aluminum Resistance of Maize Are Expressed in the Distal Part of the Transition Zone. Is Reduced Basipetal Auxin Flow Involved in Inhibition of Root Elongation by Aluminum? Plant Physiology, March 1, 2000; 122(3): 945 - 956. [Abstract] [Full Text] [PDF]

				A. M. Rashotte, S. R. Brady, R. C. Reed, S. J. Ante, and G. K. Muday Basipetal Auxin Transport Is Required for Gravitropism in Roots of Arabidopsis Plant Physiology, February 1, 2000; 122(2): 481 - 490. [Abstract] [Full Text]

				A. C. Scott and N. S. Allen Changes in Cytosolic pH within Arabidopsis Root Columella Cells Play a Key Role in the Early Signaling Pathway for Root Gravitropism Plant Physiology, December 1, 1999; 121(4): 1291 - 1298. [Abstract] [Full Text]

				R. Chen, E. Rosen, and P. H. Masson Gravitropism in Higher Plants Plant Physiology, June 1, 1999; 120(2): 343 - 350. [Full Text] [PDF]

				M. Sivaguru, D. Volkmann, H. H. Felle, and W. J. Horst Impacts of Aluminum on the Cytoskeleton of the Maize Root Apex. Short-Term Effects on the Distal Part of the Transition Zone Plant Physiology, March 1, 1999; 119(3): 1073 - 1082. [Abstract] [Full Text]

				F. Chaumont, F. Barrieu, E. M. Herman, and M. J. Chrispeels Characterization of a Maize Tonoplast Aquaporin Expressed in Zones of Cell Division and Elongation Plant Physiology, August 1, 1998; 117(4): 1143 - 1152. [Abstract] [Full Text]

				M. Sivaguru and W. J. Horst The Distal Part of the Transition Zone Is the Most Aluminum-Sensitive Apical Root Zone of Maize Plant Physiology, January 1, 1998; 116(1): 155 - 163. [Abstract] [Full Text]