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研究了外源根施甜菜碱对抗旱性不同的两个冬小麦品种幼苗抗旱性的影响。结果表明 ,水分胁迫会诱导小麦幼苗体内甜菜碱的积累 ,外源甜菜碱能提高体内甜菜碱含量 ,改善水分胁迫下两小麦品种的水分状况 ,提高其水势、膨压和相对含水量 ,这可能是通过提高小麦幼苗体内一些有机渗透调节物质 (如可溶性糖和脯氨酸 )含量进而增强其渗透调节能力而实现的。甜菜碱还能提高水分胁迫下幼苗体内SOD、APX和POD活性 ,而对CAT活性无影响。水分胁迫后 ,甜菜碱预处理的幼苗叶片丙二醛含量低于未处理幼苗 ,表明外源甜菜碱能缓解水分胁迫引起的膜脂过氧化。结果还表明 ,水分胁迫后 ,抗旱性品种的水分状况和抗氧化酶水平优于水分敏感型品种 ,外源甜菜碱在改善水分胁迫下的水分关系方面对水分敏感型品种效应更大 ,而在提高抗氧化酶活性方面对两品种无明显差异
The effects of exogenous betaine on the drought resistance of two winter wheat cultivars with different drought resistances were studied. The results showed that water stress induced the accumulation of betaine in wheat seedlings. Exogenous betaine could increase the content of betaine, improve the water status and increase the water potential, turgor pressure and relative water content of two wheat cultivars under water stress, which may be Is achieved by increasing the content of some organic osmolyte (such as soluble sugar and proline) in wheat seedling to further enhance its osmoregulation ability. Betaine also increased SOD, APX and POD activity in seedlings under water stress, but had no effect on CAT activity. Under water stress, the content of malondialdehyde in seedling leaf pretreated with betaine was lower than that in untreated seedling, indicating that exogenous betaine could alleviate the lipid peroxidation caused by water stress. The results also showed that the water status and antioxidant enzyme activity of drought-tolerant cultivars were better than that of water-sensitive cultivars under drought stress. Exogenous betaine had a greater effect on water-sensitive cultivars under water stress, There was no significant difference between the two cultivars in improving antioxidant enzyme activity