Lanthanum-induced changes in gravicurvature, calcium balance, and statocyte ultrastructure of pea roots.

A study to investigate the effects of La" ions on graviresponsiveness, statocyte ultrastructure, and calcium balance were carried out on 5-day seedlings of Pisum sativum. The results indicate that this blocker of some Ca2+ channels 1) inhibits the root graviresponsiveness, 2) disturbs statocyte polarity and changes qualitative and quantitative characteristics of some cellular organelles and compartments, 3) results in the disturbance of calcium homeostasis. Taken together, the data are consistent with the hypothesis, concerning the role of Ca2+ in gravitational signal transduction.