Dopamine (DA) is a neurotransmitter which takes charge of brain activities about memory and self-stimulation behavior in animals. Interestingly, our results suggest that DA could also give maize an “excited state”. The results showed that 1 mmol L⁻¹ DA promoted maize germination by 23.2% significantly, and accelerated the growth rate of roots and shoots by 21.4 and 24.7%, respectively. As we all known, abscisic acid (ABA) is the key hormone involved in seed dormancy. In our research, ABA levels in roots and shoots dramatically decreased by 16.45 and 57.57%, respectively. To further investigate how DA reduces the ABA level in budding seed, we studied ABA synthesis and catabolism pathway. Specific expression of key ABA-synthesis genes, such as ZmNCED1, ZmNCED3 and ZmZEP were down-regulated by DA. Simultaneously, the expression levels of ABA8OX1a and ABA8OX1b which are major transcripts of ABA 8′-hydroxylase in ABA catabolism were up-regulated at least 1.5- and 4.6-fold, respectively. Our results enriched the functions of animal hormones in plants.

多巴胺（DA）是一种神经递质，负责大脑有关动物记忆和自我刺激行为的活动。有趣的是，我们的结果表明DA也可以使玉米处于“兴奋状态”。结果表明，1 mmol L ^-1 DA显着促进玉米萌发23.2％，使根和芽的生长速率分别提高21.4％和24.7％。众所周知，脱落酸（ABA）是种子休眠的关键激素。在我们的研究中，根和茎中的ABA水平分别显着降低了16.45和57.57％。为了进一步研究DA如何降低发芽种子中的ABA水平，我们研究了ABA的合成和分解代谢途径。关键的ABA合成基因如ZmNCED1，ZmNCED3和ZmZEP的特异性表达被DA下调。同时，ABA分解代谢中ABA 8'-羟化酶的主要转录产物ABA8OX1a和ABA8OX1b的表达水平分别上调了至少1.5-和4.6-倍。我们的结果丰富了植物中动物激素的功能。