镁肥调控稻花香米香气品质的机理研究

Rice (Oryza sativa L.), one of the most important cereal crops, is facing challenges to upgrade consumption though the improvement of its quality in China. Daohuaxiang is a well-known high-quality fragrant rice variety in China, with unique characteristics of high-quality rice. However, its fragrance has weakened in recent years. Fertilization is an effective practice to improve quality of rice grains. Mg is a mineral nutrient impacting photosynthesis, carbohydrate synthesis and amino acid metabolism. Our previous studies indicated improved contents of proline by Mg fertilization, a major precursor of 2-acetyl-1-pyrroline (2AP). However, the mechanism of Mg fertilization on formation of aroma metabolites in rice remained unclear and needed to be further studied. The focus of present study will be to explore metabolic pathways involving role of Mg to improve aroma quality in rice using biochemical, physiological and molecular approaches to investigate Mg-regulated aroma metabolites and precursors, metabolization-related enzyme activities and expression level of genes. This work will provide the basis for an effective use of Mg fertilizer to increase rice quality and product consumption in future.

水稻是我国主要粮食作物之一，如何提高稻米品质是我国农产品消费升级的迫切需求，也是水稻种植业的突出挑战。稻花香作为我国最优质的水稻之一，其独特的食味品质是发展优质稻米的重要方向；但稻花香品质逐年下降，严重丧失其特性。养分与作物品质密切相关，镁在植物光合作用、碳水化合物合成、氨基酸代谢等方面起着重要作用。我们前期研究发现，喷施镁肥能够有效提高稻花香米主要香气成分2-乙酰-1-吡咯啉(2AP)合成前体脯氨酸的含量。然而，镁肥如何调控水稻香气成分合成或积累有待深入研究。本课题通过稻花香喷施镁肥试验，利用生物化学、生理、分子生物学方法，研究不同施镁条件下香气成分含量及前体物质积累、相关代谢酶活性与基因表达水平，以明确喷施镁肥对水稻香气品质的影响规律、构建镁肥调控代谢网络，从而解析镁肥调控水稻香气形成的生理机制，为合理施用镁肥提高水稻香气品质提供理论依据。

水稻是我国主要粮食作物之一，提高稻米品质是我国农产品消费升级的迫切需求，也是水稻种植业的突出挑战。养分与作物品质密切相关，镁在植物光合作用、碳水化合物合成、氨基酸代谢等方面起着重要作用。本项目围绕“镁肥调控稻米品质的机制”的关键科学问题，在前期的工作基础上，利用生物化学、生理、分子生物学方法，研究不同施镁条件下香气成分含量及前体物质积累、相关代谢酶活性与基因表达水平，取得了如下重要进展：（1）增施镁肥显著提高稻米食用品质；（2）稻米垩白粒率和垩白度显著降低，提高加工品质；（3）增施镁肥促进磷酸核苷物质（ADP，ATP）与Mg2+形成络合物，提高酶活性；（4）适量喷施镁肥显著提高脯氨酸含量、Δ1-吡咯啉-5-羧酸合成酶和脯氨酸脱氢酶活性，探明了镁促进水稻香气2-AP形成的生理机制，为合理施用镁肥提高水稻香气品质提供理论依据。