Effect of vitamin K3 on plasma membrane-bound H+-ATPase and reductase activities in plants

Vitamin K-like compounds are widely diffused in plants, but their role and function are still partially unknown. Vitamin K-1 - phylloquinone - is largely present in tylacoid membranes as electron carrier inside the PSI redox chain. More recently, it has been found that Vitamins K-1 and K-3 may also affect the plasmalemma-bound H+-ATPase and reductase activities. In this article we report the effects of Vitamin K-3 treatment on the above activities in three different conditions: in the presence of Vitamin K-3; after the addition of Vitamin K-3 to the hydroponic solution; after sonication of plasma membrane in the presence of Vitamin K-3 in the solution. Results showed that Vitamin K-3 was able to improve both plasmalemma H+-ATPase and reductase activities at a concentration that is very well tolerated by the whole plant. Our findings support the hypothesis that Vitamin K is involved in plasmalemma activities of both mono and dicotyledonous plants. (c) 2006 Elsevier Ireland Ltd. All rights reserved.