Physiological and comparative proteomic analyses in response to nitrogen application in an Amaryllidaceae plant, Lycoris aurea

摘要

Galanthamine is used as a strong reversible inhibitor of cholinesterase to increase acetylcholine sensitivity. Here, we sought to determine the effect of nitrogen (N) application on physiological and proteomic properties of Lycoris aurea (L. aurea) inorder to explore the factors that influence galanthamine biosynthesis. A marked increase in plant growth was observed under absent nitrogen condition (0 mmol L~(-1) N), while a clear stunting of growth was seen under high nitrogen condition (3.57 mmol L~(-1) N). Levels of photosynthetic pigments also showed a preference for the absent nitrogen condition. The leaves and roots of absent nitrogen plants had significantly higher galanthamine content and lower contents of free amino acids and proline compared with those of control (0.75 mmol L~(-1) N). On the other hand, galanthamine content in L. aurea was significantly reduced with high nitrogen treatment. However, the contents of free amino acids and proline were increased with high nitrogen application, suggesting that these play important roles in the storage of nitrogen in L. aurea. Next, we carried out proteomic analysis of the leaves, bulbs and roots of L. aurea treated with nitrogen by two-dimensional gel electrophoresis. Using comparative proteomic strategies, we found 11 proteins that showed significant differences among the three groups. These proteins are involved in a variety of cellular processes including energy metabolism, scavenging oxygen free radicals, cytoskeleton stabilization, galanthamine biosynthesis and cellular homeostasis. Out of the 11 proteins, the level of phenylalanine ammonia-lyase was found to correlate with that of galanthamine biosynthesis.