Arbuscular mycorrhiza impacts on drought stress of maize plants by lipid peroxidation, proline content and activity of antioxidant system

The effects of arbuscular mycorrhiza (AM) on lipid peroxidation, proline content and activity of antioxidant system in leaves and roots of Zea mays L. plants under well-watered condition and drought stress was investigated in this study. Maize genotype Zhengdan 958 was grown in a sand and black soil mixture for 4 weeks and then exposed to drought stress for 4 weeks. Plants inoculated with the AM fungus Glomus etunicatum were compared to non-inoculated plants. Drought stress significantly decreased AM root colonization and total dry weight of all maize plants. Under drought stress, mycorrhizal plant had lower leaf malondialdehyde (MDA) content and relative permeability of leaf membrane. Root MDA content of AM-inoculated plants was lower than that of corresponding non-inoculated ones. AM symbiosis increased leaf proline content of maize plants. However, root proline content of mycorrhizal plants was lower than in non-mycorrhizal plants. The differences of antioxidant enzyme activities were significant between inoculated and non-inoculated plants. Compared with non-mycorrhizal plants, the activity of leaf superoxide dismutase (SOD) and catalase (CAT) of mycorrhizal plants were lower at well-watered condition, but higher at drought-stressed condition. AM-inoculated plants had markedly higher root SOD activity than non-inoculated plants regardless of water treatments. The activity of peroxidase (POD) in the leaves and roots of mycorrhizal maize plants were higher than that of non-mycorrhizal plants. The results suggested that AM fungus could alleviate the detrimental effect of drought stress by reducing MDA content and membrane permeability, and icreasing proline content and antioxidant enzyme activities.