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Author Korenkov, Victor ♦ Hirschi, Kendal ♦ Crutchfield, James D. ♦ Wagner, George J.
Source SpringerLink
Content type Text
Publisher Springer-Verlag
File Format PDF
Copyright Year ©2007
Language English
Subject Domain (in DDC) Natural sciences & mathematics ♦ Life sciences; biology
Subject Keyword Metal tolerance ♦ Metal toxicity ♦ CAX ♦ Antiporter ♦ Membrane leakage ♦ Proton pump ♦ Forestry ♦ Ecology ♦ Agriculture ♦ Plant Sciences
Abstract Sequestration mechanisms that prevent high concentrations of free metal ions from persisting in metabolically active compartments of cells are thought to be central in tolerance of plants to high levels of divalent cation metals. Expression of AtCAX2 or AtCAX4, which encode divalent cation/proton antiporters, in Nicotiana tabacum cv. KY14 results in enhanced Cd- and Zn-selective transport into root tonoplast vesicles, and enhanced Cd accumulation in roots of plants exposed to moderate, 0.02 μM Cd in solution culture (Korenkov et al. in Planta 225:403–411, 2007). Here we investigated effects of expressing AtCAX2 and AtCAX4 in the same lines on tolerance to growth with near-incipient toxicity levels of Cd, Zn and Mn. Less growth inhibition (higher tolerance) to all three metals was observed in 35S::AtCAX2 and FS3::AtCAX4 expressing plants. Consistent with the tolerance observed for Cd was the finding that while root tonoplast vesicle proton pump activities of control and FS3AtCAX4 expressing plants grown in 3 μM Cd were similarly reduced, and vesicle proton leak was enhanced, root tonoplast vesicle antiporter activity of these plants remained elevated above that in controls. We suggest that CAX antiporters, unlike tonoplast proton pump and membrane integrity, are not negatively impacted by high Cd, and that supplementation of tonoplast with AtCAX compensates somewhat for reduced tonoplast proton pump and proton leak, and thereby results in sufficient vacuolar Cd sequestration to provide higher tolerance. Results are consistent with the view that CAX2 and CAX4 antiporters of tonoplast play a role in tolerance to high, toxic levels of Cd, Zn, and Mn in tobacco.
ISSN 00320935
Age Range 18 to 22 years ♦ above 22 year
Educational Use Research
Education Level UG and PG
Learning Resource Type Article
Publisher Date 2007-07-18
Publisher Place Berlin/Heidelberg
e-ISSN 14322048
Journal Planta
Volume Number 226
Issue Number 6
Page Count 9
Starting Page 1379
Ending Page 1387

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Source: SpringerLink