Biological clock of plants is sensitive to nutrient status

March 16th, 2008 - 12:02 pm ICT by admin  

Washington, March 16 (ANI): An international team of researchers have identified that the master gene controlling the biological clock in plants is sensitive to nutrient status.

The study was conducted by a team of researchers at New York University’s Center for Genomics and Systems Biology, Chile’s Pontificia Universidad Catolica de Chile, Dartmouth College, and Cold Spring Harbor Labs.

For the study, the researchers took the case of the plant Arabidopsis.

Using a systems biological analysis of genome-scale data from Arabidopsis, the researchers identified that the master gene controlling its biological clock is sensitive to nutrient status.

This hypothesis derived from multi-network analysis of Arabidopsis genomic data, and validated experimentally, has shed light on how nutrients affect the molecular networks controlling plant growth and development in response to nutrient sensing.

According to Rodrigo A. Gutierrez and Gloria Coruzzi, the study’s lead authors, the systems biology approach to uncovering nutrient regulated gene networks provides new targets for engineering traits in plants of agronomic interest such as increased nitrogen use efficiency, which could lead to reduced fertilizer cost and lowering ground water contamination by nitrates.

Nitrogen is an essential nutrient and a metabolic signal that is sensed and converted, resulting in the control of gene expression in plants. In addition, nitrate has been shown to serve as a signal for the control of gene expression in Arabidopsis, the first flowering plant to have its entire genome sequenced.

There is existing evidence, on a gene-by-gene basis, that products of nitrogen assimilation, the amino acids glutamate (Glu) or glutamine (Gln), might serve as signals of organic nitrogen status that are sensed and in turn regulate gene expression.

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 plant’s 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.

This study indicates that nitrogen nutrition affects CCA1, the central clock gene of plants, suggesting nutritional regulation of the biological clock occurs in plants. (ANI)

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