Photosynthesis: the next generation

Basic high school biology could help increase crop yields.

New information about a more efficient type of photosynthesis that could be used to increase farm production and reduce the amount of carbon in the air has been uncovered by scientists at Yale, Cornell’s Boyce Thompson Institute for Plant Research, Iowa State University and the University of Toronto. This more efficient form of photosynthesis, called C4 photosynthesis, has been of interest to biologists since it was discovered in the late 1960s, Yale biology professor Timothy Nelson said, but this new research focused on the genetic changes that occur in a leaf during photosynthesis.

“The question of understanding photosynthesis is not a purely academic one,” Cornell professor and co-author of the new paper Tom Brutnell said. “It has important implications for a number of pressing style issues now.”

Nelson’s team of researchers utilized various techniques to help track the changes that occur in a plant during C4 photosynthetic development. (C4 photosynthesis is different from C3 photosynthesis in that C4 photosynthesis supercharges carbon dioxide in order to make better use of it.)

The goal of the project was to sample the developmental time points along a developing maize leaf in order to obtain the entire spectrum of gene activity at each point in development, Nelson said. He said the “massive” amount of data obtained allows one to see what the 20,000 genes are doing at any particular time.

Brutnell said an unexpected result of the experiment was the discovery of the dynamic nature of changes in gene expression. He added that the study found there is a 10,000-fold difference in how abundant gene transcripts are at the tip of the leaf compared to the base of the leaf, indicating that there are very discrete areas inside the leaf that carry out specific functions.

The data collected in the study is now available in an online database for scientists and researchers who want information about progressive developmental changes in leaves.

“This collection of data is really unprecedented in animals or in plants,” Nelson said.

Brutnell said that the collaborative approach to research is what made this study a dynamic process.

“We realized we had a limitation in our expertise and needed to go out and find collaborations,” Brutnell said. “I think that’s very important for the way we do science today since it’s much harder to run projects completely self-contained in your laboratory.”

The cross-disciplinary nature of the research, which drew on people whose expertise ranged from physiology and proteomics to statistics and computational biology, allowed work to be divided according to each research team’s individual skill sets, Brutnell said.

Looking ahead, Brutnell said the next step in the research process is to engineer rice so that it performs the more efficient C4 photosynthesis in hot or dry climates.

If this were achieved, Brutnell said, rice yields might improve by up to 50 percent by making rice plants use water and nitrogen more efficiently.

“When water becomes a real limiting factor, it’s going to be important to have a plant that’s most efficient and uses limited water,” Brutnell said.

The article detailing this research project was published in the Oct. 31 issue of the journal Nature Genetics.

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