Lead disturbs microtubule organization in the root meristem of Zea mays

Lead is an environmental pollutant that interferes with plant growth. Unfortunately, the mechanisms of lead toxicity in plants are still poorly understood. In this study, we have investigated both the deposition sites and sources of cellular toxicity of lead in maize seedlings (Zea mays L. cv. Golden Cross Bantam). Using atomic absorption spectroscopy and X-ray fluorescence microprobing, we show that lead accumulation is highest in the root meristem, and that the accumulation occurs both in the apoplast and symplast. Since cells are dividing vigorously in this region and because microtubules play an important role in cell division, we have further examined the effects of lead on microtubules in the root meristem. Lead treatment perturbed the alignment of microtubules in a concentration-dependent manner beginning at 10 μM. Microtubules of different regions of the root meristem and in different stages of the cell cycle showed differential susceptibility to lead. These effects do not appear to be general phenomena common to toxic metals, since aluminum and copper, at concentrations that decreased root growth to a comparable level, did not have the same detrimental effects on microtubules. Based on these results, we suggest that the damage to microtubules is partly responsible for lead-associated toxicity in plants.

[1]  L. Kochian,et al.  Aluminium Toxicity in Roots: An Investigation of Spatial Sensitivity and the Role of the Root Cap , 1993 .

[2]  H. Zimmermann,et al.  Interaction of triethyl lead chloride with microtubules in vitro and in mammalian cells. , 1985, Experimental cell research.

[3]  S. Lane,et al.  A HISTOCHEMICAL INVESTIGATION OF LEAD UPTAKE IN RAPHANUS SATIVUS , 1977 .

[4]  C. Helma,et al.  Genotoxic effects of heavy metals: Comparative investigation with plant bioassays , 1998, Environmental and molecular mutagenesis.

[5]  B. Hohn,et al.  The Allium cepa chromosome aberration test reliably measures genotoxicity of soils of inhabited areas in the Ukraine contaminated by the Chernobyl accident. , 1998, Mutation research.

[6]  G. Röderer,et al.  Influence of inorganic and triethyl lead on nuclear migration and ultrastructure of Micrasterias. , 1990, Ecotoxicology and environmental safety.

[7]  I. Raskin,et al.  Use of plant roots for phytoremediation and molecular farming. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[8]  B. B. Panda,et al.  Persistence of cadmium-induced adaptive response to genotoxicity of maleic hydrazide and methyl mercuric chloride in root meristem cells of Allium cepa L.: differential inhibition by cycloheximide and buthionine sulfoximine. , 1997, Mutation research.

[9]  Baluska,et al.  Impacts of aluminum on the cytoskeleton of the maize root apex. short-term effects on the distal part of the transition zone , 1999, Plant physiology.

[10]  M. Wierzbicka.  Lead accumulation and its translocation barriers in roots of Allium cepa L.-autoradiographic and ultrastructural studies. , 1987, Plant, cell & environment.

[11]  Sally Brown,et al.  Phytoremediation of soil metals. , 1997, Current opinion in biotechnology.

[12]  C. Rensing,et al.  Pb(II)-translocating P-type ATPases* , 1998, The Journal of Biological Chemistry.

[13]  C. Rieder,et al.  Colcemid and the mitotic cycle. , 1992, Journal of cell science.

[14]  S. D. Cunningham,et al.  Lead phytoextraction: species variation in lead uptake and translocation , 1996 .

[15]  G. Röderer.  On the toxic effects of tetraethyl lead and its derivatives on the chrysophyte Poterioochromonas malhamensis. VI. Effects on lorica formation, mitosis, and cytokinesis. , 1986, Environmental research.

[16]  T. Ma,et al.  The improved Allium/Vicia root tip micronucleus assay for clastogenicity of environmental pollutants. , 1995, Mutation research.

[17]  Peter E. Body M. App. Sc.,et al.  Environmental lead: A review , 1991 .

[18]  Raskin,et al.  The role of EDTA in lead transport and accumulation by indian mustard , 1998, Plant physiology.

[19]  M. Olszewska,et al.  The timing of synthesis of proteins required for mitotic spindle and phragmoplast in partially synchronized root meristems of Vicia faba L. , 1990, European journal of cell biology.

[20]  C. Stournaras,et al.  The interaction of triethyl lead with tubulin and microtubules. , 1988, Mutation research.

[21]  L. Kochian,et al.  Transport kinetics and metabolism of exogenously applied putrescine in roots of intact maize seedlings. , 1992, Plant physiology.

[22]  G. Röderer,et al.  Influence of trimethyl lead and inorganic lead on the in vitro assembly of microtubules from mammalian brain. , 1983, Neurotoxicology.