Giving maize an excited start – Effects of dopamine on maize germination

Abstract

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.

Keywords

• dopamine (DA)
• maize germination
• ABA synthesis
• ABA catabolism