壳寡糖对PEG胁迫下小麦幼苗生长及抗氧化系统的影响

为明确壳寡糖对小麦幼苗干旱胁迫的缓解机制,采用水培试验,研究了喷施不同浓度壳寡糖溶液(10mg/L、100 mg/L和200 mg/L)对20%PEG模拟干旱胁迫下小麦幼苗生长、叶片超氧阴离子(O·-2)和MDA含量、抗氧化酶活性以及渗透调节物质含量的影响。结果显示:喷施3种浓度壳寡糖可明显促进PEG胁迫下小麦幼苗的生长,处理48 h后幼苗株高、根长、地上部和根部干重均显著增加(200 mg/L壳寡糖对根部干重影响除外);处理24 h和48 h后,喷施100 mg/L壳寡糖可明显降低PEG胁迫下小麦叶片的O·-2含量,而3种浓度壳寡糖均可明显降低MDA含量;相比10 mg/L和200 mg/L浓度,喷施100 mg/L壳寡糖可明显增强PEG胁迫下小麦叶片的抗氧化系统活性,SOD、POD和CAT活性及可溶性蛋白、可溶性糖和脯氨酸含量均显著提高(48h时脯氨酸含量变化除外)。上述结果表明,100 mg/L是较适宜的喷施浓度。PEG胁迫下,喷施适宜浓度的壳寡糖能明显促进小麦地上部和根部的生长,降低叶片的活性氧含量和膜脂过氧化程度,提高抗氧化酶活性和渗透调节物质含量,增强小麦对干旱胁迫的抵抗能力。

Effects of Chitooligosaccharide on Plant Growth and Antioxidant System in Seedlings of Wheat (Triticum aestivum L.) Under PEG Stress

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.