Effects of Ca addition on the uptake, translocation, and distribution of Cd in Arabidopsis thaliana.
Cadmium (Cd) pollution poses a risk to human health for its accumulation in soil and crops, but this can be alleviated by calcium (Ca) addition. However, its mechanism remains unclear yet. In this study, Arabidopsis thaliana was used to explore the alleviating effects of Ca on Cd toxicity and its specific function during uptake, upward-translocation, and distribution of Cd. Supplementing plants with 5mM CaCl2alleviated the intoxication symptoms caused by 50μM CdCl2, such as smaller leaves, early bolting and root browning. Ca addition decreased uptake of Cd, possibly by reducing the physical adsorption of Cd since the root cell membrane was well maintained and lignin deposition was decreased as well, and by decreasing symplastic Cd transport. Expression of the genes involved (AtZIP2 and AtZIP4) was also decreased. In addition, Ca accumulated in the plant shoot to help facilitating the upward-translocation of Cd, with evidence of higher translocation factor and expression of genes that were involved in Ca transport (AtPCR1) and Cd xylem loading (AtHMA2 and AtHMA4). Dithizone-staining of Cd in leaves showed that in Cd+Ca-treated plants, Ca addition initially protected the leaf stomata by preventing Cd from entering guard cells, but with prolonged Cd treatment facilitated the Cd accumulation around trichomes and maybe its excretion. We conclude that Ca promotes the upward-translocation of Cd and changes its distribution in leaves. The results may have relevance for bioremediation.
Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, School of Life Science, South China Normal University, Guangzhou 510631, China.
Lihua
L
Zeng
Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, School of Life Science, South China Normal University, Guangzhou 510631, China.
Ting
T
Zhu
Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, School of Life Science, South China Normal University, Guangzhou 510631, China.
Ya
Y
Gao
Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, School of Life Science, South China Normal University, Guangzhou 510631, China.
Yutao
Y
Wang
Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, School of Life Science, South China Normal University, Guangzhou 510631, China.
Chanjuan
C
Ning
Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, School of Life Science, South China Normal University, Guangzhou 510631, China; Department of Biology, Molecular Cell Biology, Lund University, Lund 22467, Sweden.
Lars Olof
LO
Björn
Cooperative Wildlife Research Laboratory and Department of Zoology, Southern Illinois University Carbondale, Carbondale, IL 62901, USA.
Da
D
Chen
Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, School of Life Science, South China Normal University, Guangzhou 510631, China. Electronic address: lishsh@scnu.edu.cn.
Shaoshan
S
Li
D000251:Adenosine Triphosphatases / Q000235:genetics; D017360:Arabidopsis / Q000187:drug effects* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics; D001692:Biological Transport / Q000187:drug effects* / Q000235:genetics; D002104:Cadmium / Q000378:metabolism* / Q000633:toxicity*; D002118:Calcium / Q000494:pharmacology*; D027682:Cation Transport Proteins / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D052584:Xylem / Q000378:metabolism
D029681:Arabidopsis Proteins; D027682:Cation Transport Proteins; C000620826:PCR1 protein, Arabidopsis; C000620827:ZIP2 protein, Arabidopsis; C520833:Zip4 protein, Arabidopsis; D002104:Cadmium; D000251:Adenosine Triphosphatases; C494967:HMA2 protein, Arabidopsis; C477864:HMA4 protein, Arabidopsis; D002118:Calcium
Alleviating effect; Cd distribution; Cd toxicity; Cd uptake and translocation; Exogenous Ca