ISSN:
1365-3040
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
The short-term effects of rare earth elements on pollen germination and tube growth were tested. Concentrations of 2.5∼20 µm lanthanum(La3+) or cerium (Ce3+)increased pollen germination and pollen tube growth, whereas concentrations higher than 40 µm La3+ and Ce3+ inhibited this process. The most effective concentration of La3+ needed for promotion shifted from 10 to 40 µm, depending on the Ca2+ concentration in the medium. Calmodulin (CaM) antagonist W7-agarose and anti-CaM antibody depressed La3+-promoted pollen germination and tube growth in a dose-dependent manner. La3+–CaM complexes (La3+–CaM) increased pollen germination and tube growth more than CaM or La3+ alone. Pertussis toxin (PTX) inhibited La3+-promoted pollen germination and tube growth. Cholera toxin (CTX) partially recovered the inhibition of the above La3+-promoted process by the anti-CaM antibody. Concentrations of 10−7∼10−9 m La3+–CaM increased GTPase activity inside plasma membrane vesicles of the pollen tube, but apo-CaM or La3+ alone had no positive effects. The results suggest that apoplastic CaM may be involved in the promotion effects of lower concentrations of La3+ on pollen germination and tube growth, and the heterotrimeric G-protein on the plasma membrane may transduce La3+-activated CaM signalling. The present studies provide an apoplastic mechanism for short-term effects of rare earth elements at lower concentrations in the pollen system.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1046/j.1365-3040.2003.01021.x
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