Physiological analysis reveals relatively higher salt tolerance in roots of Ilex integra than in those of Ilex purpurea

Determining the responses of candidate plants to salt stress is a prerequisite for selecting and breeding suitable plants with high salt tolerance to grow in coastal mudflat areas with high salinity. Here, 2-year cutting seedlings of Ilex purpurea Hassk. (local species) and I. integra Thunb. (introduced species) were grown in pots in a glasshouse and irrigated with a Hoagland-NaCl solution at 0, 24, and 48 h. Root samples were collected at 0, 1, 6, 24, and 72 h, and concentration of Na+ ion; content of proline, soluble carbohydrate, malondialdehyde (MDA), H2O2 and ascorbate; and activity of three key antioxidative enzymes were measured. Roots of I. integra accumulated relatively less Na+ and had less membrane lipid peroxidation and H2O2 during salt stress, thus indicating a relatively higher salt tolerance than roots of I. purpurea. Values for ascorbate content and antioxidant enzymatic activity suggest that the antioxidant ascorbate and antioxidative catalase may play substantial roles for scavenging reactive oxygen species in I. integra roots during salt treatment. Thus, I. integra is apparently more suitable for growing in local highly saline coastal mudflats.