不同性别杨树应答低氮胁迫的生理学研究

Physiological Study on Sexual Differences in Response to Nitrogen Stress in Poplar Trees

杨树是林业研究领域的模式植物,其作为雌雄异株的代表植物之一,是研究性别差异导致的生理、基因表达以及表观遗传等热门领域的重要研究对象。氮元素是植物生长发育必不可少的营养元素,氮吸收及同化的机理,尤其是在同一种植物的不同性别中氮元素利用差异的机理研究还比较少。本文采用水培的方法对正常条件和低氮条件下雌雄杨树的碳氮含量、光合作用效率及其参数、抗氧化酶活性,以及可溶性蛋白与游离氨基酸含量的变化进行研究。结果表明:在低氮条件下,植株碳含量增加,雌株比雄株对低氮更加敏感。总活性氧物质(ROS)含量在雌雄单株中没有显著差异,但活性氧清除酶,如过氧化物酶(POD)、超氧化物岐化酶(SOD)、谷胱甘肽合成酶(GS)等,在雌株中的活性比雄株高。可溶性蛋白含量在雌株与雄株中没有显著差异,而氨基酸的组成与含量在雌雄单株间以及胁迫处理前后有显著差异,天门冬氨酸(Asp),丝氨酸(Ser),以及精氨酸(Arg)等含量在雄株中较高,大部分游离氨基酸含量受低氮胁迫抑制,而蛋氨酸(Met)、亮氨酸(Leu)与络氨酸(Tyr)等的含量基本不受影响。本研究主要从生理学角度分析了低氮胁迫条件下杨树雌株与雄株的生理学差异,并对雌株比雄株对低氮胁迫敏感可能的机制进行了讨论。

Poplar tree is a model plant in forestry research.As The representative dioecious plant,poplar plays an important role in physiological,gene expression and derived epigenetic researches from sexual differences.Nitrogen is essential for plant growth and development,however,the mechanisms of nitrogen absorption and assimilation especially the nitrogen use efficiency in two different genders of one plant have not been well studied yet.In this study,a systematical examination of carbon and nitrogen content,photosynthesis efficiency and its parameters,the antioxidant enzyme activities as well as soluble protein and free amino acid concentrations were performed in male and female poplar trees under normal and nitrogen stress conditions.It was found that carbon content increased under nitrogen stress condition,and the female plants were more sensitive than the male plants.Total reactive oxygen species （ROS） concentration was insignificantly different between the male and female plants,but the activities of antioxidant enzymes,such as peroxidase （POD）,superoxide dismutase （SOD） and glutathione synthetase （GS）,were higher in female individuals than that in male ones.Soluble protein concentrations were similar in the two genders,while the amino acids content varied a lot in male and female individuals under the control and under the nitrogen stress conditions.Aspartic acid （Asp）,serine（Ser）,as well as arginine （Arg）,etc.were higher in male plants under normal condition;most of the free amino acids were suppressed by nitrogen stress except methionine （Met）,leucine （Leu） and tyrosine （Tyr）,etc.We mainly analyzed physiological difference between the female and male poplar plants under the normal and nitrogen conditions.A and the potential mechanisms were also discussed.