Abstract
Understanding which metabolites accumulate in arrhythmic plants will help us to elucidate the mechanisms regulating plant growth and development by the circadian clock system. To this end, we performed comprehensive metabolite phenotyping of two arrhythmic mutants: Arabidopsis pseudo-response regulator (PRR9, 7, and 5) triple mutant and CCA1-overexpression. Our approach, which is based on gas chromatography-mass spectrometry, demonstrated that the triple mutant exhibits large alteration in primary metabolism. The triple mutant is characterized by a drastic increase in the metabolite levels of tricarboxylic acid (TCA)-cycle intermediates, osmolytes and several antioxidants. The results from both light/dark cycle and continuous light suggest that the linkage between the circadian clock and the TCA-cycle is very robust. Our integrated approach revealed that PRR9/7/5 negatively regulates the chlorophyll, carotenoid-ABA, and vitamin E biosynthetic pathways, and highlights them as novel outputs of the circadian clock.
