Systems biology approach identifies nutrient regulation of biological clock...(/p To identify genome-wide responses ...)

To identify genome-wide responses to such organic nitrogen signals, the researchers treated Arabidopsis seedlings with inorganic nitrogen (N) in both the presence and the absence of chemicals that inhibit the assimilation into organic N and conducted a genome-wide analysis of all genes whose expression responds to inorganic or organic forms of nitrogen. Using an integrated network model of molecular interactions for Arabidopsis--constructed by the researchers--in which approximately 7,000 genes are connected by 230,000 molecular interactions, they uncovered a sub-network of genes regulated by organic nitrogen that includes a highly connected network hub CCA1, which controls a plants biological clock, and target genes involved in nitrogen assimilation.

The findings thus provide evidence that plant nutrition, like animal nutrition, is tightly linked to circadian, or biological clock, functions as scientists have previously hypothesized. Other researchers have recently found that the central clock gene Per2 is necessary for food anticipation in mice. This study indicates that nitrogen nutrition affects CCA1, the central clock gene of plants, suggesting nutritional regulation of the biological clock occurs in plants.

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