Farmers and other astute observers of nature have long known that crops like corn and sorghum grow taller at night. But the biochemical mechanisms that control this nightly stem elongation, common to most plants, have been something of a mystery to biologistsuntil now.
In this week's early online publication of the journal Nature, biologists at the University of California, San Diego report their discovery of a protein complex they call the "evening complex" that regulates the rhythmic growth of plants during the night. More importantly, the biologists show how this protein complex is intricately coordinated through the biological clock with the genes that promote stem elongation in a way that could enable plant breeders to engineer new varieties of crops that grow faster, produce greater yields of food or generate more biomass per acre of land for conversion into biofuels.
"This discovery gives us a molecular understanding of how the biological clock is regulating cyclic growth in plants," said Steve Kay, dean of UC San Diego's Division of Biological Sciences, who headed the research effort. "And it instantly gives us a handle on how we might manipulate and control plant yield or biomass deposition."
While most people assume that plants grow at a slow and steady rate throughout the day and night, Charles Darwin and others more than a century ago observed that they actually grow in spurts late at night, with plant stems elongating fastest in the hours just before dawn.
"Plants actually grow rhythmically," said Kay. "Some plants, like sorghum, have the ability to elongate a centimeter or more each night."
The UCSD biologists initially focused their attention on three genes from a tiny mustard plant called Arabidopsis, which is used by geneticists as a laboratory model for plants. When they are disabled by mutations, these three genes disrupt the plant's biological clock and promote both stem elongation and earl
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University of California - San Diego