大麦氮敏感基因型苗期对氮饥饿的生理响应

以大田试验获得的大麦氮敏感基因型BI-45为材料，利用溶液培养方法，测定了苗期株高、根长、叶绿素含量、含氮量、谷氨酰胺合成酶和硝酸还原酶活性，以及与氮代谢相关的基因（GSI-GSl-2、GSI-3、GS2、Narl、NRT2．J、NRT2-2、NRT2-3和NRT2-4）的表达。结果表明：相对于正常供氮，氮饥饿胁迫下，BI-45根和叶中的氮素利用率提高，含氮量降低，叶绿素含量减少，根冠比增加；叶片中的谷氨酰胺合成酶活性和硝酸还原酶的活性高于根，但是，与叶中的相比，根中的谷氨酰胺合成酶活性升高及硝酸还原酶活性降低的差异性更显著；与正常供氮相比，氮饥饿处理下，根中基因傩家族，基Narl和硝酸盐转运蛋白基因NRT2家族的相对表达量皆达到显著性差异，其中GSl-I、GSl-2和NRT2-2在苗期大麦氮饥饿处理下表现尤为突出，并且在6h都有上调表达。

The Physiological Responses of a Nitrogen Sensitive Genotype to Nitrogen Starvation in Barley Seedlings

In this study, using nitrogen sensitive genotype BI-45 of barley obtained from field experiments, we investigated the morphological, physiological and molecular responses, such as stem length, root length, chlorophyll content, nitrogen content, glutamine synthetase activity, nitrate reductase activity and the expression of several genes related to N uptake and assimilation. The results showed that nitrogen use efficiency and the ratios of shoot and root increase while chlorophyll and nitrogen content decrease under N starvation. Both GS and NR activities were higher in leaves than those in roots. However, compared with leaves, significant differences can be found in roots, that is, N starvation increased GS activity but decreased NR activity. In addition, genes （GS family, Narl and NRT2 family） in the roots also showed more significant differences, especially GS11, GS12, and NRT2.2 which were all up-regulated at 6 h might play important roles in N assimilation of barley seedlings under N starvation condition.