Drought Affects the Antioxidant System and Stomatal Aperture in Zanthoxylum bungeanum Maxim.

Abstract

When under drought, plants activate a range of self-protective responses. Among these are activation of the antioxidant system and changes in stomatal aperture. The antioxidant system can remove the reactive oxygen species produced under drought conditions and so mitigate oxidative damage. Water becomes a severely limiting resource for plants suffering drought stress, so they generally close their stomata to reduce water loss. We examined changes in the activities of the antioxidant enzymes and altered gene expression patterns in Zanthoxylum bungeanum plants exposed to drought by irrigation with 20% PEG6000. We also recorded changes in stomatal aperture as the drought persisted. Relationships between the antioxidant system and stomatal aperture were analyzed in relation to gene expression. The results indicate that under drought stress, POD, CAT, APX, proline, MDA and related genes all show positive responses to drought, while SOD and its genes showed a negative response. The relationship between drought duration and stomatal aperture was considered. Stomatal aperture declines exponentially as drought duration increases.