Fertilizers shape plant genomes

March 10, 2009

By hammersmith

[Source Elie Dolgin< The Scientist] – Spraying plants with nitrogen-rich fertilizers does more than just make crops grow bigger; it also molds the chemical composition of their genomes and proteomes, according to a study published online last week (Mar. 2) in the journal Molecular Biology & Evolution.

“This tells us how modifications in the environment can have a big effect on a species and its genome, and how quickly it can happen,” said Sudhir Kumar, an evolutionary biologist at Arizona State University’s Biodesign Institute in Tempe who led the study.

Nitrogen is a scant resource in nature. So Kumar and his postdoc Claudia Acquisti set out to test whether plants conserve the essential element by opting to use nitrogen-poor nucleic acids such as thymine, which only contains two nitrogen atoms, as opposed to guanine with its whopping five N atoms. All told, an AT nucleotide combo equates to a single nitrogen molecule “savings” compared to a GC duo. Thus, if nitrogen limitation has shaped plant genomes, one would expect to find more AT-rich regions, especially in highly transcribed parts of the genome, which use a lot of molecular resources.

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