Cerium nitrate improves salt tolerance of wheat seedlings by regulating the antioxidant capacity of chloroplasts

The effects of Ce(NO3)(3) on the antioxidant capacity in the chloroplasts of salt-stressed wheat (Triticum aestivum L.) seedlings were investigated. The results showed that salt stress (40, 80, 120, or 160 mM NaCl) significantly increased the activities of ascorbate peroxidase, glutathione reductase, superoxide dismutase, catalase, and glutathione peroxidase, the content of malondialdehyde (MDA) and hydrogen peroxide (H2O2), but significantly reduced the ratios of reduced ascorbate (AsA) to dehydroascorbate (DHA) and reduced glutathione to oxidizided glutathione (GSH/GSSG), the content of chlorophylls (Chls) and carotenoids, net photosynthetic rate, plant height, plant dry mass and root length compared with the control. Compared with NaCl stress alone, application of NaCl + Ce(NO3)(3) further enhanced the activities of above mentioned enzymes, increased the ratios of AsA/DHA and GSH/GSSG, the content of Chs and carotenoids, net photosynthetic rate, plant height, plant dry mass, and root length, and significantly reduced the content of MDA and H2O2 in chloroplasts. Meanwhile, Ce(NO3)(3) alone also significantly enhanced the above mentioned indicators, but had no significant effect on the content of MDA and H2O2 compared with the control. Our results suggested that Ce(NO3)(3) up-regulated the antioxidant capacity of chloroplast, which improved the wheat salt tolerance.