Mechanism Study Of γ-aminobutyric Acid On Flowering Time Promotion In Arabidopsis

Control of flowering time is one of the most important physiological activitiesduring the life cycle of plant. Lots of molecular genetic studies on Arabidopsisthaliana flowering revealed that there are four main flowering controlling pathways:photoperiod,vernalization, autonomous,and gibberelin pathway. Although we learnedmuch about the molecular mechanism of Arabidopsis flowering time control, theexact mechanism about how γ-aminobutyric acid (GABA) promotes Arabidopsisflowering time remains unknown. The aim of this research is attempt to explore themolecular mechanism underlying.γ-aminobutyric acid (GABA) is a non-protein amino acid, and it exists inprokaryotic and eukaryotic organisms.GABA can also serve as an intracellularsignaling molecule to regulate a wide range of gene expression. To explore themechanism of GABA on plant flowering, different concentration of exogenousGABA (1,5,10mmol/L) was sprayed on Arabidopsis7days seedlings at1dayintervals, the mock was spraying with clear water. This treatment was continued to4weeks. Focusing on some key genes involing flowering time control,we use RT-PCRand qRT-PCR techniques to investigate the role of GABA in this phenomenon. Theresults were as follows:1GABA at different extent could promote early flowering in Arabidopsis grownboth in long-day (16h light/8h dark cycle) and short-day (8h light/16h dark cycle)conditions;2In the present experiments,we selected seven key genes, the results ofsemi-quantitative RT-PCR showed that GABA signals could trigger the up-regulationof CO, LHY, FCA,LFY, and the down-regulation of FLC expression. There is nodifferences in the expression of VRN1,VRN2;3Quantitative RT-PCR (qRT-PCR) technique was employed to further investigatethe expression level of flowering inhibitor gene FLC, autonomous flowering pathwaygene FCA and inflorescence meristem identification gene LFY. The results indicatedthat, GABA treatment could down regulate the expression level FLC2-5folds,whereas the expression level of FCA was enhanced1.5-6times, and the expressionlevel of LFY was increased3-11folds.4The preliminary results indicated that, Under long-day conditions of GABAinduced by FCA, LFY, FLC gene expression changes were significantly higher thanthat of short day, showed that the GABA Promoting blossom pathways may be relatedto photoperiod pathway.