关键词: 小麦幼苗, PEG胁迫, 壳寡糖, 活性氧, 抗氧化系统

Abstract: In order to clarify the mitigation mechanism of chitooligosaccharide in protecting wheat seedlings against drought stress, this paper investigated the effects of different concentrations of chitooligosaccharide solution (10 mg/L, 100 mg/L and 200 mg/L) on the growth, leaves O·-2 and MDA contents, antioxidant enzyme activity and osmosis-regulating substances contents of wheat (Triticum aestivum L.) under 20% PEG stress by a hydroponic experiment. The results showed that spraying 3 concentrations of chitooligosaccharide could obviously promote the growth of wheat seedlings under PEG stress, with the plant height, root length, shoot and root dry weight increased significantly after treated for 48 h (except for the root dry weight of 200 mg/L). After treated for 24 h and 48 h, foliar-spraying 100 mg/L chitooligosaccharide decreased significantly the leaves O·-2 contents under PEG stress, and the 3 concentrations of chitooligosaccharide decreased significantly the leaves MDA contents. Compared with the concentrations of 10 mg/L and 200 mg/L, spraying 100 mg/L chitooligosaccharide could significantly enhance the leaves antioxidant activity of wheat seedlings under PEG stress, with the SOD, POD and CAT activities and soluble protein, soluble sugar and proline contents increased significantly (except for proline contents at 48 h). Thus, the 100 mg/L chitooligosaccharide solution was more appropriate as spraying concentration. These findings indicated that appropriate spraying concentration of chitooligosaccharide solution could effectively enhance the wheat resistance to PEG stress by promoting the growth of shoots and roots, decreasing leaves reactive oxygen species accumulation and membrane lipid peroxidation, and improving the antioxidant enzymes activity and osmosis-regulating substances contents.

Key words: wheat seedlings, PEG stress, chitooligosaccharide, reactive oxygen species, antioxidant system