Dopamine plays numerous physiological roles in plants. We explored its role in the regulation of growth, nutrient absorption, and response to nitrogen (N) deficiency in Malus hupehensis Rehd. Under low N condition, plant growth slowed, and the net photosynthetic rates, chlorophyll contents, and maximal quantum yield of PSII (F_v/F_m) decreased significantly. However, the application of 100 μmol L⁻¹ exogenous dopamine significantly reduced the inhibition of low N stress on plant growth. In addition to modifying root system architecture under low N supply, exogenous dopamine also changed the uptake, transport, and distribution of N, P, and K. Furthermore, exogenous dopamine enhances the tolerance to low nitrogen stress by increasing the activity of enzymes (nitrate reductase, nitrite reductase, glutamic acid synthase and glutamine synthetase) involved in N metabolism. We also found that exogenous dopamine promoted the expression of ethylene signaling genes (ERF1, ERF2, EIL1, ERS2, ETR1, and EIN4) under low N stress. Therefore, we hypothesized that ethylene might be involved in dopamine response to low N stress in M. hupehensis. Our results suggest that exogenous dopamine can mitigate low N stress by regulating the absorption of mineral nutrients, possibly through the regulation of the ethylene signaling pathway.

多巴胺在植物中起许多生理作用。我们探索了其在平邑甜茶中生长，养分吸收和对氮（N）缺乏反应的调节作用。在低氮条件下，植物生长减慢，PSII的净光合速率，叶绿素含量和最大量子产率（F _v / F _m）显着下降。但是，100μmolL ^-1的应用外源多巴胺显着降低了低氮胁迫对植物生长的抑制作用。外源多巴胺除了在低氮供应下改变根系结构外，还改变了氮，磷和钾的吸收，转运和分布。此外，外源多巴胺还通过增加酶的活性（硝酸盐）来增强对低氮胁迫的耐受性。还原酶，亚硝酸还原酶，谷氨酸合成酶和谷氨酰胺合成酶）参与氮素代谢。我们还发现，在低氮胁迫下，外源多巴胺可促进乙烯信号基因（ERF1，ERF2，EIL1，ERS2，ETR1和EIN4）的表达。因此，我们假设乙烯可能参与了平邑甜茶对低氮胁迫的多巴胺反应。 我们的结果表明，外源多巴胺可以通过调节矿物质营养物质的吸收（可能通过调节乙烯信号途径）来缓解低氮胁迫。