Influence of fusicoccin and gramicidin‐D on Rb⁺ transport in intact barley seedlings

Abstract

The influence of the fungal toxin fusicoccin or the quasi‐ionophore gramicidin‐D on Rb⁺ transport in intact barley seedlings (Hordeum vulgare cv Morex) was studied. Fusicoccin (1 μM) or gramlcidin‐D (3.2 μM) were added to absorption solutions which contained 0.1 mM RbCl and 0.5 mM CaSO₄, and the Rb⁺ content of roots and shoots determined over a 24 hour period. Roots of fusicoccin‐treated seedlings contained greater amounts of Rb⁺ throughout the entire course of the experiment, and roots of gramlcidin‐D treated seedlings contained greater amounts of Rb⁺ for the first 10 hours but contained smaller amounts of Rb⁺ for the rest of the experiment when compared with control seedlings. However, shoots of seedlings treated with fusicoccin or gramicidin‐D contained smaller amounts of Rb⁺ than the control seedlings throughout the entire course of the experiment. These results are discussed in terms of the interrelationships of the ion transport mechanisms which mediate the vectorial movement of ions from the absorption solution to the stelar apoplasm of the root.

Keywords:

• Ionophore
• fungal toxin
• ion translocation

Notes

Present address: USDA, ARS, Northern Regional Research Center, 1815 North University Street, Peoria, Illinois 61604.