遮光对黄瓜幼苗同化物代谢相关糖和酶的影响

The Influence of Shading Stress on Assimilate Metabolism Related Sugars and Enzymes in Cucumber Seedlings

试验中发现,黄瓜幼苗遮光叶片蔗糖含量略高于未遮光对照叶片,而棉籽糖、肌醇半乳糖苷和水苏糖含量显著低于对照叶片。叶片中肌醇半乳糖苷合成酶活性和基因转录水平变化趋势一致,遮光叶片显著低于对照叶片;棉籽糖合成酶活性差异不显著,但是遮光叶片棉籽糖合成酶基因转录水平显著低于对照叶片;遮光叶片水苏糖合成酶活性显著低于对照,且相关基因转录水平变化与酶活性变化一致;此外蔗糖非发酵相关蛋白激酶1基因(SnRK1)表达水平在遮荫处理6 h时显著高于对照。表明在遮光胁迫下,黄瓜幼苗通过调控肌醇半乳糖苷合成酶、水苏糖合成酶和蔗糖非发酵相关蛋白激酶1相关基因表达和酶活性,维持叶片蔗糖含量,提供生长所需能量,保证叶片存活。

In this study,results of liquid chromatography analysis showed sucrose content in leaves of cucumber seedlings under shading treatment was slightly higher than control. While galactinol,raffinose and stachyose contents of shading leaves were lower than that of control. The change of galactinol synthase activity was consistent with galactinol synthase genes expression level,which of shading leaves were lower than control;the activity of raffinose synthase is not significantly different between shading leaves and control,while the transcription level of raffinose synthase genes under shading condition was significantly lower than control;the activity of stachyose synthase of shading leaves was lower than control,and the expression level of stachyose synthase genes was consistent with the activity. In addition,the expression level of SNF1-related protein kinase 1 gene（SnRK1）of shading leaves was higher than control at 12：00 am of first day under 6 h shading treatment,which indicated that SnRK1 occurred in response of shading stress. Together,these results suggested that under shading stress the gene expression and activities of galactinol synthase,stachyose synthase,and SnRK1 in cucumber were regulated to maintain the content of sucrose,provide the energy for growth,and ensure the survival of leaves.