Effect of Vanadate on Bean Leaf Movement, Stomatal Conductance, Barley Leaf Unrolling, Respiration, and Phosphatase Activity

Abstract

Vanadate (Na3VO4) inhibits leaf movement and stomatal conductance Qf Phaseons vulgaris L. cv. Carlos Favorit in light-dark cycles as well as photomorphogenetic leaf unrolling of Hordeum vulgare L. cv. Rupal. Inhi-bition was 50% by 10 to 100 micromolar vanadate and 100% by millimolar vanadate. Leaf unrolling was also inhibited by oligomycin and diethylstil-bestrol. Millimolar vanadate is required to affect respiration of bean plants and barley leaves, while even this concentration has no effect on respiration of isolated pulvinal tissue. A nonspecific phosphatase activity extracted from both bean pulvini and barley leaves was found in all of four fractions of a differential centrifuga-tion procedure (ie. cell walls + nuclei, mitochondria, microsomes,