Giant grass offers clues to growing corn in cooler climes, research...(warm conditions Long said. In C4 pl...)

In C4 plants, PPDK catalyzes a chemical reaction in the leaf critical to the cascade of reactions that convert carbon from carbon dioxide into starches that form the plant's tissues.

Previous studies had shown that PPDK is generally not very stable in cold conditions. The protein is made up of four subunits, which tend to come apart at low temperatures, Long said.

To test how cold temperatures affect the protein when it is expressed in cells at high concentrations, post-doctoral fellow Dafu Wang cloned the PPDK gene into E. coli bacteria to produce large quantities of the protein.

"What he showed in the test tube was that if you concentrate the protein, then it becomes more resistant to cold," Long said. "At higher concentration the protein creates its own microenvironment where in the cold it doesn't come apart. This appears to be the secret of success for Miscanthus at low temperature: Expressing more of the protein allows it to photosynthesize at low temperature where corn can't."

The next step for the researchers is to develop a corn plant in which this gene is expressed at high levels to determine if that will make the corn more tolerant of low temperatures, Long said. Cold weather after emergence of corn in the spring or in late summer during grain-filling can limit photosynthesis, he said.

"This change should make corn more resistant to these cold weather events."

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