Plants grow bigger and more vigorously through changes in their inter...( AUSTIN TexasHybrid plants like corn ...)

AUSTIN, TexasHybrid plants, like corn, grow bigger and better than their parents because many of their genes for photosynthesis and starch metabolism are more active during the day, report researchers from The University of Texas at Austin in a new study published in the journal Nature.

Their research has relevance in many areas of agriculture, and could result in new methods to increase biomass for biofuels and seed production for animal feedstock and human consumption.

It has long been known that hybrid plants such as hybrid corn are more vigorous than their parents. They are larger and have more biomass and bigger seeds. The same is true for plants that are polyploid, meaning that they have two or more sets of chromosomes. Over 70 percent of all flowering plants, including many important agricultural crops such as wheat, cotton, canola, sugarcane and banana, are naturally polyploid.

Until now, the molecular mechanisms for hybrid and polyploid vigor have largely been unknown.

"Before this discovery, no one really knew how hybridization and polyploidy led to increased vigor," says lead author Dr. Jeffrey Chen, the D. J. Sibley Centennial Professor of Plant Molecular Genetics. "This is certainly not the only mechanism behind this phenomenon, but it is a big step forward."

The key, Chen and his colleagues studying Arabidopsis plants found, is the increased expression of genes involved in photosynthesis and starch metabolism in hybrids and polyploids. These genes were expressed at high levels during the day, several-fold increases over their parents.

The hybrids and polyploids exhibited increased photosynthesis, higher amounts of chlorophyll and greater starch accumulation than their parents, all of which led to their growing larger.

Also, growth vigor was higher in allotetraploid plants (polyploids formed by combining two different Arabidopsis species) than standard hybrids (formed through
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