多巴胺对苹果氮利用效率的影响与机制研究

Over-fertilization of nitrogen (N) in present apple orchard in China was very common. It is one of the main factors to cause low N use efficiency and threaten the healthy development of apple production. Dopamine, a natural product of the catecholamine pathway, is a biogenic amine with a 3,4-dihydroxy-substituted phenyl ring, and very little is known about its physiological significance in plants. We have previous found that dopamine has an positive impact on ion uptake, but the physilogical and molecular mechanism remain unknow. In this project, a hydroponics culture system will be conducted to compare physiological and molecular changes in Malus hupehensis seedlings when dopamine is combined with a low or normal supply of N (0.1 mM or 2mM N). The spatial and temporal dynamics of NH4+ and NO3- will be monitored by the non-invasive micro-test system. Subsequently, the uptake, transport, resorption and utilization of 15NH4+ and 15NO3- will be analyzed. Furthermore, the transcript levels of AMTs, NRTs, NR, NiR, GS, Fd-GOGAT and NADH-GOGAT involved in N uptake and assimilation will also be analyzed. Based on the above research, we will reveal the mechanism of dopamine on N use efficiency. The knowledge gained from this study will not only provide the theoretical and scientific basis for increasing N use efficiency, but also help the healthy development of apple production. Reducing N fertilizer and improving N use efficiency were useful to alleviate the pollution of environmental.

我国苹果园过量施氮（N）和N利用率低的问题十分严重，对苹果产业健康发展造成极大威胁。多巴胺是儿茶酚胺合成途径中的自然产物，是一类含有苯二酚结构的生物胺，有关植物中多巴胺生理功能的研究较少。我们前期研究发现，多巴胺能够促进矿质元素的吸收，但其机理尚不清楚。本项目拟以苹果平邑甜茶实生苗为试材，应用非损伤微测技术，探明多巴胺对根系吸收NH4+和NO3-的时空动态变化影响；运用15N同位素示踪技术，揭示多巴胺对15NH4+和15NO3-吸收、转移、重吸收和利用效率的影响；利用实时荧光定量PCR分析，明确多巴胺对N吸收利用的调控与AMTs、NRTs、NR、NiR、GS、Fd-GOGAT、NADH-GOGAT转录丰度的关系。在此研究基础上，阐明多巴胺对N高效吸收利用的调控机理。研究结果将为提高N利用率提供理论基础和科学依据，有利于保障苹果产业可持续发展，也有利于缓解果园过量施氮造成的环境问题。

我国苹果园过量施氮（N）和N利用率低的问题十分严重，对苹果产业健康发展造成极大威胁。多巴胺是儿茶酚胺合成途径中的自然产物，是一类含有苯二酚结构的生物胺，在植物体内具有许多重要的生理功能。前期研究发现，多巴胺能够调控矿质元素的吸收，但其作用机理尚不清楚。本项目以平邑甜茶苹果实生苗为试材，利用生理生化等技术初步探明了多巴胺调控苹果氮素高效吸收利用的作用机理。低氮胁迫下，多巴胺能够维持苹果叶片较高的叶绿素浓度，提高抗氧化酶活性，改变植株根系构型，促进根系对NH4+和NO3-的动态吸收，缓解低氮对植株生长的抑制作用。同时，多巴胺还能够通过提高氮代谢相关酶活性及氮转运蛋白基因转录表达水平调控平邑甜茶植株对氮素的吸收、转移和分配，提高苹果植株氮利用效率。研究结果将丰富苹果抗逆调控理论，对提高果园肥效和促进土壤贫瘠地区果业发展具有重要的理论意义和潜在应用价值。