Genes associated with heavy metal tolerance and accumulation in Zn/Cd hyperaccumulator Arabidopsis halleri: a genomic survey with cDNA microarray.
To survive in variable soil conditions, plants possess homeostatic mechanisms to maintain a suitable concentration of essential heavy metal ions. Certain plants, inhabiting heavy metal-enriched or -contaminated soil, thus are named hyperaccumulators. Studying hyperaccumulators has great potential to provide information for phytoremediation. To better understand the hyperaccumulating mechanism, we used an Arabidopsis cDNA microarray to compare the gene expression of the Zn/Cd hyperaccumulator Arabidopsis halleri and a nonhyperaccumulator, Arabidopsis thaliana. By analyzing the expression of metal-chelators, antioxidation-related genes, and transporters, we revealed a few novel molecular features. We found that metallothionein 2b and 3, APX and MDAR4 in the ascorbate-glutathione pathway, and certain metal transporters in P(1B)-type ATPase, ZIP, Nramp, and CDF families, are expressed at higher levels in A. halleri than in A. thaliana. We further validated that the enzymatic activity of ascorbate peroxidase and class III peroxidases are highly elevated in A. halleri. This observation positively correlates with the higher ability of A. halleri to detoxify H2O2 produced by cadmium and paraquat treatments. We thus suggest that higher peroxidase activities contribute to the heavy metal tolerance in A. halleri by alleviating the ROS damage. We have revealed genes that could be candidates for the future engineering of plants with large biomass for use in phytoremediation.
Chiang
Huai-Chih
HC
Agriculture Biotechnology Research Center, Academia Sinica, 128 Academia Road Section 2, Taipei, Taiwan 11529, ROC.
Lo
Jing-Chi
JC
Yeh
Kuo-Chen
KC
D000975:Antioxidants / Q000737:chemistry; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry; D001692:Biological Transport; D002104:Cadmium / Q000032:analysis*; D018076:DNA, Complementary / Q000378:metabolism; D004784:Environmental Monitoring / Q000379:methods*; D018745:Genome, Plant; D008670:Metals; D019216:Metals, Heavy / Q000032:analysis* / Q000494:pharmacology / Q000633:toxicity; D020411:Oligonucleotide Array Sequence Analysis; D018384:Oxidative Stress; D017382:Reactive Oxygen Species; D015032:Zinc / Q000032:analysis*
D000975:Antioxidants; D029681:Arabidopsis Proteins; D018076:DNA, Complementary; D008670:Metals; D019216:Metals, Heavy; D017382:Reactive Oxygen Species; D002104:Cadmium; D015032:Zinc