Mycorrhiza has a direct effect on reactive oxygen metabolism of drought-stressed citrus

Abstract

A greenhouse experiment was conducted to investigate the dynamic trend of symbiotic development in Citrus sinensis/Poncirus trifoliata trees colonized by Glomus versiforme during 12-day lasting drought and to evaluate correlation between symbiotic development and reactive oxygen metabolism of citrus. One year after planting, water was withheld from all trees for 12 days. During the drought stress mycorrhizal colonization and arbuscles showed a durative reduction. Mycorrhizal trees maintained significantly lower contents of superoxide anion, hydrogen peroxide and malondialdehyde than non-mycorrhizal control throughout the experiment. There were significantly greater activities of superoxide dismutase, guaiacol peroxidase and catalase in mycorrhizal trees throughout the drought stress period. Ascorbate and glutathione contents of mycorrhizal trees were notably higher than those of uninoculated ones during 12 days of drought stress. Correlation analysis showed that not vesicles and entry points but mycorrhizal colonization and arbusculcs had a substantive direct effect on reactive oxygen metabolism. These results suggest that mycorrhizal colonization and arbuscles play a major role in improving reactive oxygen metabolism of drought-stressed citrus, thus inducing a lower oxidative damage.