ISSN:
1365-3040
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
The pattern of mRNA accumulation of genes coding for the putative potassium transporters HvHAK1A, HvHAK1B, HvHAK2, HvHAK3 and HvAKT1 along seminal roots was studied in K+ starved barley (Hordeum vulgare) plants. Accumulation of these transcripts was lower in young, relative to older root zones, indicating the existence of a coordinated spatial pattern of gene regulation. A study of rubidium (Rb+) uptake kinetics showed that for all root zones transport can be dissected into a linear and a saturable component. Paralleling the pattern of mRNA accumulation the Vmax of the saturable term was lowest in the youngest root zone. No differences in the Rb+ Km or in the linear term were observed among root zones. K+ channel blockers Ba2+, Al3+, and tetraethylammonium exerted no effect on Rb+ uptake from diluted Rb+ solutions, while it was inhibited by Cs+, NH4+, methylamine, and K+ in all root zones. These results show that high-affinity Rb+ transport over the entire axis is mediated by transporters displaying HAK1-like properties. The observation of a differential effect of Na+ on Rb+ uptake along roots is compatible with a change in the proportion and/or the activity of those transport entities following a longitudinal gradient.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-3040.2005.01334.x
