小麦胚芽鞘扩展蛋白特性及对水分胁迫的响应

扩展蛋白是植物细胞壁延伸过程中的关键调节因子,在植物的生长发育以及对逆境的响应过程中起着重要作用。本文选用小麦(HF 9703)胚芽鞘为材料,采用Hepes法和SDS法分别提取小麦胚芽鞘扩展蛋白,通过改良的植物组织伸长测定仪测定其活性,并利用扩展蛋白抗体进行免疫印迹以检测其丰度,主要研究了小麦胚芽鞘扩展蛋白的特性及对水分胁迫的响应。结果表明:Hepes法提取的扩展蛋白活性较高,而SDS法的提取效率高;离体小麦胚芽鞘扩展蛋白的活性具有pH依赖性,且随缓冲液的交替更换(pH 4.5:pH 6.8)而反复逆转;扩展蛋白主要定位于细胞壁中;小麦胚芽鞘扩展蛋白和黄瓜下胚轴扩展蛋白具有交叉重组活性,但这种活性具有种属特异性。水分胁迫诱导小麦胚芽鞘扩展蛋白的活性和丰度提高,扩展蛋白活性的提高在小麦对水分胁迫的抗性方面可能具有重要作用。

The Characteristics of Expansins in Wheat Coleoptiles and Their Responses to Water Stress

As the key regulators of cell wall extension during plant growth,expansins play an important role in regulating the development and response of plants to adverse environment.The characteristics of expansins in wheat coleoptiles and their responses to water stress were studied.Expansin proteins were extracted from wheat coleoptiles by the methods of Hepes or SDS.The activities of expansins were measured with an improved extensometer and the amount of expansins was measured by immunoblot analysis with the expansin antibody.The results showed that in coleoptiles,the extension of na- tive cell walls depended on acidic pH,and the expansins were found to be located at cell walls by location analysis. Expansins from wheat coleoptiles could induce cell wall extension both of cucumber hypocotyls and coleoptiles, and vice versa,albeit with differences noted in exten- sion activity.The changes in activity and abundance of expansins in wheat coleoptiles in response to water stress suggest that expansins may play a significant role in the tolerance of wheat plants to water stress.