Fertilizer-free corn?

- Dan Murphy, AgNetwork, June 9, 2010
 
Of course, synthetic biology is still a young discipline within molecular biology. In fact, if one were to measure its maturity in "science years"-like how we estimate the relative human age of a dog or cat-then synthetic biology would be a rowdy teen-ager: full of energy and promise, but a ways away from reaching its full potential.

That said, in slightly more than a decade of activity this exciting new science already promises to generate some potentially dramatic improvements in agricultural (and many other) systems. But to appreciate how today's synthetic biological research might impact tomorrow's food production, first we've got to wade through some pretty daunting science.

Here goes.
Circuit training

A simplified explanation of synthetic biology is that it involves engineering of gene networks that can control biological processes at the cellular level. If "basic" biotechnology utilizes the transplanting of a gene from one organism to another to introduce new functionality-such as soybeans that are resistant to a particular herbicide-then synthetic biology might be understood as an attempt to reprogram more complex biological activity through construction of gene expression networks.

What the heck are gene expression networks? you're probably asking. According to Kaustubh Bhalerao, an assistant professor of Agricultural and Biological Engineering at the University of Illinois and one of the leading synthetic biology researchers, these networks operate as the biological equivalent of electronic control circuits. As he explained it in a recent Trends in Biotechnology article, "Synthetic biology attempts to construct artificial circuits that can control biological functions in potentially transformational ways."

Bhalerao is currently leading a multidisciplinary research team, partially funded by the National Science Foundation, that includes scientists from the University of California-San Francisco, Stanford University, the University of Cambridge and New Castle University. The team is working to build systems that enable bacteria to communicate with and control plant cells-which, by the way, is the basis of how legumes fix nitrogen.

More on that is a moment.  Already, scientists have used synthetic biology techniques to create a "toggle switch" that governs whether gene expression is turned on or off in response to a stimulus. The next phase-and where it begins to get interesting-is developing entire gene networks that could trigger more complex biological activity.

Like programming corn to fix nitrogen, for example.  The use of nitrogen fertilizer is essential for profitable corn growing, but its sustainability long-term is beginning to be questioned, and if nothing else, it represents a significant production cost. But is it really possible to "teach" corn to fix its own nitrogen, eliminating or at least reducing the need for nitrogen fertilizer applications?

Bhalerao says yes.  "We now understand enough about how genes work and how proteins are produced that we can actually think about reprogramming how cells work," he explained.

Soybeans fix nitrogen by signaling certain bacteria to colonize in the plant's roots. Then, once the right biochemical environment has developed, the bacteria being fixing nitrogen that the plant can utilize. That's why soybeans are naturally high in nitrogen and a protein-rich food source.

"Why don't we teach corn how to do this?" he asked. "This would reduce the need for petroleum-based fertilizers, which has huge implications for sustainable agriculture."

As synthetic biological research forges ahead, one of the areas of greatest progress has been the creation of a biological repository for interchangeable gene circuits that can literally be assembled in modular fashion to build progressively more complex gene expression networks. Does that sound like the way electronic devices are built? It should, because it is.

"To compare [synthetic biology] with electronics, where it's drawing a lot of its ideas and terminology from, we cannot yet foresee what the Internet of this technology is going to look like," Bhalerao said. "We are still at the stage of developing the transistor."

For more information on synthetic biology and Prof. Bhalerao's research, log onto the Bhalerao Group website at http://abe-bhaleraolab.age.uiuc.edu/

Dan Murphy is a veteran food-industry journalist and commentator