Effects of dichromate on growth and root system architecture of Arabidopsis thaliana seedlings

• Published in: Plant science (Limerick) Vol. 172; no. 4; pp. 684 - 691
• Main Authors: Castro, Randy Ortiz, Trujillo, Miguel Martínez, López Bucio, José, Cervantes, Carlos, Dubrovsky, Joseph
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 01-04-2007; Elsevier Science
• Subjects: Arabidopsis thaliana; auxins; Biological and medical sciences; cell differentiation; cell division; chromium; Development; Fundamental and applied biological sciences. Psychology; gene expression regulation; Genes. Genome; Hexavalent chromium; Mineral nutrients; Molecular and cellular biology; Molecular genetics; morphogenesis; potassium dichromate; Root architecture; root systems; seed germination; seedling growth; seedlings; Arabidopsis thaliana; Hexavalent chromium; Development; Root architecture; Mineral nutrients; Root; Cruciferae; Growth; Dicotyledones; Angiospermae; Spermatophyta
• ISSN: 0168-9452; 1873-2259
• DOI: 10.1016/j.plantsci.2006.11.004

The hexavalent form of chromium [Cr(VI)] is toxic for most organisms; however, very little information is available regarding the effects of this metal on plant morphogenesis. In this work, we investigated the effects of Cr(VI) on the growth and development of
Arabidopsis thaliana, a species widely used as a model for studying the diverse physiological and cellular processes in plants. Elongation of root hairs and biomass production were stimulated by relatively low concentrations (100
μM) of Cr(VI) as potassium dichromate. Concentrations of Cr(VI) greater than 200
μM were toxic to plants as revealed both by arrested growth of roots and shoots and the development of chlorosis in leaves. At 200
μM the primary root growth was totally inhibited but the plants continued their growth manifesting different alterations in root development. These alterations correlated with changes in mitotic activity and in cellular expansion. The analyses of
A. thaliana transgenic plants that express the auxin-inducible marker
DR5:uidA, and the response of the auxin-resistant mutants
axr2 and
aux1–7 to dichromate suggest that auxins do not participate as mediators in the cellular and physiological responses to this metal. The primary root growth inhibition by 200
μM dichromate was alleviated by more than 70% by increasing the sulfate, phosphate or nitrate concentration in the media, which suggests a relation of dichromate with these mineral nutrients.