Connections between circadian clocks and carbon metabolism reveal species-specific effects on growth control.
The plant circadian system exists in a framework of rhythmic metabolism. Much has been learned about the transcriptional machinery that generates the clock rhythm. Interestingly, these components are largely conserved between monocots and dicots, but key differences in physiological and developmental output processes have been found. How the clock coordinates carbon metabolism to drive plant growth performance is described with a focus on starch breakdown in Arabidopsis. It is proposed that clock effects on plant growth and fitness are more complex than just matching internal with external rhythms. Interesting recent findings support that the products of photosynthesis, probably sucrose, in turn feeds back to the clock to set its rhythm. In this way, the clock both controls and is controlled by carbon fluxes. This has an interesting connection to stress signalling and water-use efficiency, and it is now known that the clock and abscisic acid pathways are reciprocally coordinated. These processes converge to drive growth in a species-specific context such that predictions from the Arabidopsis model to other species can be restricted. This has been seen from phenotypic growth studies that revealed that dicot shoot growth is rhythmic whereas monocot shoot growth is continuous. Taken together, emerging evidence suggests reciprocal interactions between metabolism, the circadian clock, and stress signalling to control growth and fitness in Arabidopsis, but transferability to other species is not always possible due to species-specific effects.
Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, Cologne 50829, Germany.
Lukas M
LM
Müller
Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, Cologne 50829, Germany Institute of Plant Genetics, Heinrich-Heine-University, Düsseldorf 40225, Germany Cluster of Excellence on Plant Sciences, Düsseldorf 40225, Germany korff@mpipz.mpg.de davis@york.ac.uk.
Maria
M
von Korff
Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, Cologne 50829, Germany Department of Biology, University of York, York, YO10 5DD, UK korff@mpipz.mpg.de davis@york.ac.uk.
Seth J
SJ
Davis
D002244:Carbon / Q000378:metabolism*; D057906:Circadian Clocks; D008954:Models, Biological; D010641:Phenotype; D063245:Plant Development; D010944:Plants / Q000378:metabolism*; D013045:Species Specificity
D002244:Carbon
Arabidopsis; barley; circadian clock; diurnal; growth control; hormone signalling; sucrose.