水分逆境对发草脯氨酸及其代谢途径的影响

Effect of water stress on proline accumulation and metabolic pathways in Deschampsia caespitosa

本研究以发草为研究对象,通过盆栽模拟水分胁迫,研究干旱、水涝胁迫下发草地上部分及根系中脯氨酸(Pro)积累状况及其代谢途径中底物、中间产物和关键酶的变化。结果显示:1)干旱胁迫和水涝胁迫均使发草Pro含量显著升高(P<0.05),相同的水分处理下发草地上部分及根系中Pro含量相差不大。2)干旱胁迫和水涝胁迫下,发草地上部分和根系中谷氨酸(Glu)含量均显著下降(P<0.05),相同的水分处理下根系中Glu含量大于地上部分。水分胁迫使发草地上部分的鸟氨酸(Orn)含量显著下降(P<0.05),而根系中Orn含量没有显著变化。同时,干旱胁迫和水涝胁迫下,发草地上部分和根系中Δ^(1)-吡咯琳-5-羧酸合成酶、鸟氨酸转氨酶(δ-OAT)、Δ^(1)-吡咯琳-5-羧酸还原酶的活性均显著增强(P<0.05),且地上部分δ-OAT活性强于根系。另外,Δ^(1)-吡咯琳-5-羧酸脱氢酶和脯氨酸脱氢酶活性显著降低(P<0.05)。研究结果表明发草通过积累Pro缓解干旱和水涝胁迫,地上部分Pro的积累是Glu途径和Orn途径协同作用的结果,但根系中Pro的积累以Glu途径为主。

This research studied the accumulation of proline(Pro)and changes in the substrate,intermediate products and key enzymes in the Pro metabolic pathway in shoot and root tissues of Deschampsia caespitosa under drought and waterlogging stresses.It was found that:1)Both drought and waterlogging stresses significantly increased the proline content of D.caespitosa(P<0.05),and there was little difference between the proline content of the shoot and root under the same water treatment.2)Under drought and waterlogging stresses,the glutamate content in the shoots and roots of D.caespitosa were significantly(P<0.05)decreased,but the glutamate concentration in the roots was greater than that in the shoots under the same water treatment.Water stress caused a significant decrease in ornithine content in the shoots(P<0.05),but not in roots.At the same time,the activities ofΔ^(1)-pyrroline-5-carboxylic acid synthetase,ornithine aminotransferase(δ-OAT)andΔ^(1)-pyrroline-5-carboxylic acid reductase in the shoot and root tissues of D.caespitosa were significantly increased under drought and waterlogging stresses(P<0.05),and the activity ofδ-OAT in shoots was stronger than in roots.In addition,the activities ofΔ^(1)-pyrroline-5-carboxylic acid dehydrogenase and proline dehydrogenase were significantly reduced(P<0.05).The results showed that the active accumulation of proline was a primary response of D.caespitosa in alleviation of drought and waterlogging stress.The glutamate and ornithine pathways operated synergetically in the shoots,but the glutamic acid pathway was the main pathway in the roots.