Durham, NC If you eat bread stuffing or grain-fed turkey this Thanksgiving, give thanks to the grasses a family of plants that includes wheat, oats, corn and rice. Some grasses, such as corn and sugar cane, have evolved a unique way of harvesting energy from the sun that's more efficient in hot, arid conditions. A new grass family tree reveals how this mode of photosynthesis came to be.
The results may one day help scientists develop more drought-tolerant grains, say scientists working at the U. S. National Evolutionary Synthesis Center.
From the grasslands of North America, to the pampas of South America, to the steppes of Eurasia and the savannas of the tropics, the grass family contains more than 10,000 species, including the world's three most important crops: wheat, rice and corn. We rely on grasses for sugar, liquor, bread, and livestock fodder.
Like all plants, grasses harvest energy from sunlight by means of photosynthesis. But grasses use two strategies that differ in how they take up carbon dioxide from the air and convert it into the starches and sugars vital to plant growth. The majority of grasses use a mode of photosynthesis called the C3 pathway, but many species especially those in hot, tropical climates use an alternate mode of photosynthesis known as C4. In hot, arid environments, C4 grasses such as maize, sugar cane, sorghum and millet have a leg up over C3 plants because they use water more efficiently.
An international team of researchers wanted to figure out how many times, and when, the C4 strategy came to be. To find out, they used DNA sequence data from three chloroplast genes to reconstruct the grass family tree. The resulting phylogeny represents 531 species, including 93 species for which DNA sequence data was previously unavailable.
"By working collaboratively across many labs, from the US to Argentina to Ireland to Switzerland with some people providing new plant material, and
|Contact: Robin Ann Smith|
National Evolutionary Synthesis Center (NESCent)