DOE $1.85 Million Grant Funds Sorghum Photosynthesis Study

A University of Illinois research team received a $1.85 million grant from the U.S. Department of Energy (DOE) to study photosynthesis efficiency in sorghum, an important crop for bioenergy feedstock. The grant is part of a $178 million DOE initiative to advance bioenergy technology.

Photosynthesis, the ability to capture sunlight and turn it into sugars, is necessary for plant health and productivity. It is the source, directly or indirectly, of all of our food, most of our fuel and all bioproducts. Most plants can adapt their photosynthesis machinery to increase efficiency in shaded environments. However, sorghum belongs to a group of plants that lose photosynthetic efficiency in the lower, shaded leaves within a canopy. This leads to a 10 to 20% loss of potential yield.

"Maximizing yield per acre is critical to the economic viability of bioenergy crops. The bioenergy sorghums are very productive, yet without this maladaptive response to shading, they could be even more productive," states project co-investigator Steve Long, Ikenberry Endowed Chair of Plant Biology and Crop Sciences and Director of Realizing Increased Photosynthetic Efficiency (RIPE) at U of I.

The grant project aims to study the causes of sorghum's photosynthetic inefficiency in shaded canopies, and to develop solutions to improve productivity and increase yield. The researchers plan to investigate transcriptional factors to determine which, if any, are involved in the maladaptive loss of photosynthetic efficiency.

"Molecular work in crops can be a huge challenge, because it takes years to develop transgenic lines and observe what the genes do. Our approach uses a transient system to deliver transcription factors directly to leaves, allowing us to determine their targets rapidly and in vivo," says Laurie Leonelli, assistant professor in the Department of Agricultural and Biological Engineering and principal investigator on the grant.

Transcription factors are proteins that affect the expression of multiple genes and control the development of many plant processes, Leonelli explains.

"We will look at changes in gene expression between the top of the canopy and the shaded part of the canopy and match these changes in expression to transcription factors that physically interact with their regulatory domain," she notes. "Once we know which transcription factors are involved in the loss of efficiency, we can start looking for ways to change their expression with the end goal of restoring photosynthetic efficiency in the shade."

This methodology will greatly speed up the process of determining transcription factor function, allowing the researchers to obtain results in months rather than years.

"We have two aims: One is to develop a system to study transcription factors in these plants much faster. The other is to use what we learn from our transcription factor studies to actually start attacking this problem of lost potential," Leonelli concludes.

Leonelli and Long will also collaborate on the project with Matthew Brooks, research scientist with the USDA-ARS Global Change and Photosynthesis Research Unit.