Resumo

ORTIZ-CASTRO, R. et al. Restoration of root growth using inorganic nutrients in Arabidopsis thaliana L. exposed to chromium. Terra Latinoam [online]. 2009, vol.27, n.2, pp.97-103. ISSN 2395-8030.

Cr (VI) uptake by roots occurs through an active transport system, but there is little information on the specific mechanism involved in this process. Using the model plant Arabidopsis thaliana, an in vitro bioassay was devised to study the effects of Cr on root growth to obtain novel information on the role of nutrient interactions in root responses to Cr. In A. thaliana, a 200 µM concentration of potassium dichromate inhibited primary root growth. To evaluate the effects of different mineral nutrients in root response to Cr, we analyzed the responses of A. thaliana transgenic plants that express the AtCycB1;1 promoter fused to the β-glucuronidase (uidA) reporter gene. Plants expressing the AtCycB1;1:uidA construct were grown in MS-agar medium (Murashige-Skoog) supplied with 10 or 15 µM concentrations of phosphate, sulfate and nitrate, with and without 200 µM dichromate. Primary root growth in 200 µM dichromate was largely restored by phosphate and sulfate treatments (84 and 63%, respectively), but not by nitrates; this suggests a physiological relationship of these nutrients with root growth responses to dichromate. Restoration of primary root growth by nutrients directly correlated with normal mitotic activity in the root meristem, as revealed by expression of the marker AtCycB1;1::uidA, suggesting that primary root growth is inhibited by dichromate mainly because it affects cell division.

Palavras-chave : cellular division; plants; metals; phosphates; sulfates.

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