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Potassium
Potassium-Potassium (K+) is an essential
nutrient for plant growth and development. It is the most abundant cation in plant
cells and can comprise as much as 10% of plant dry weight. Plant roots take up
K+ from a wide range of external concentrations ([K+]ext), which typically vary
from 0.1 to 10m, while in some intensively cultivated areas such as rice fields
of Southeast Asia, the depletion of soil K+ threatens to reduce crop yields. Other environmental stresses, such as metal
toxicity, salinity, and drought, are known to adversely affect K+ uptake and transport
by plants, and such stresses can often be ameliorated by increased K+ supply.
The link between K+ and crop production has been highlighted in two recent
reviews: one on the role of K+ in reducing the effects of pests and disease on plants
\ and the other on the importance of K+ in the on set of sodium (Na+) toxicity.
| Potassium |
The extraction of K+ from
soil and its distribution within the plant require the presence of membrane-bound
transport proteins. A large number of such transporters have now been identified
at the molecular level, demonstrating the complexnature of K+ transport. The physiological
role sof these proteins in primary K+ influx, efflux, compartmen- tation, and transport
within the plant have been partially characterized, while many putative K+ transporters
and transport regulators are currently under investigation. The present review will
begin with a synopsis of the functions of K+, then discuss the known classes of
K+ transporters and their regulation, with attention to special topics such as
K+ -use efficiency and root zonation. Throughout, we shall assess some of the latest
investigations into K+ transport at cellular and whole-plantlevels. It is our hope
to generate new discussion for K+ transport research by bringing to get her important
advances in plant molecular biology and physiology.
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