Title: Difference in the root structure of hyperaccumulator Thlaspi caerulescens and non-hyperaccumulator Thlaspi arvense

Authors: I. Zelko, A. Lux, K. Czibula

Addresses: Department of Plant Physiology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynska dolina B-2, 84215 Bratislava, Slovakia. ' Department of Plant Physiology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynska dolina B-2, 84215 Bratislava, Slovakia. ' Department of Plant Physiology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynska dolina B-2, 84215 Bratislava, Slovakia

Abstract: The primary root structure of Zn/Cd hyperaccumulator Thlaspi caerulescens was compared with the root anatomy of closely related non-accumulator Thlaspi arvense. The most striking structure formed close to the root tip in T. caerulescens, but not in T. arvense, is the peri-endodermal layer of cells with irregularly thickened inner tangential walls. This layer observed in some species of Brassicaceae by early anatomists and described as |reseau sus-endodermique| is composed of secondary cell walls impregnated by lignin, and it forms a compact cylinder encircling the endodermis. The differences in the proportions of individual tissues – rhizodermis, cortex, stele and endodermis – of the two species are statistically insignificant. However, there are differences in the cell arrangement. The precise function of the lignified cell wall thickening of the peri-endodermal layer of T. caerulescens is unclear at present. Some possible roles are discussed and its potential relation with metal hyperaccumulation and/or tolerance should be investigated.

Keywords: cell wall thickenings; endodermis; heavy metal hyperaccumulators; root anatomy; Thlaspi arvense; Thlaspi caerulescens; root structure; heavy metals; environmental pollution.

DOI: 10.1504/IJEP.2008.019387

International Journal of Environment and Pollution, 2008 Vol.33 No.2/3, pp.123 - 132

Published online: 11 Jul 2008 *

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