Chiang Mai Thailand, Nov. 18, 2010 — Imagine taking a rice plant, an organism with a C3 pathway, and converting it into a C4 pathway plant. Now I know what you’re thinking. You’re thinking “That’s just crazy talk!” and you may be correct. But tell that to Dr. Jacque Dionora at theInternational Institute for Rice Research (IRRI) in Los Baños, Philippines. Jacque is a member of IRRI’s C4 Rice Project that is funded to do just that. “Why is this important?” you might ask. Well, the difference in the efficiency between C3 and C4 plants is huge, and such a conversion, were it to prove possible to achieve, may be the difference between feeding 6 billion people and feeding the more than 9 billion projected in the upcoming decades to centuries. Here is a definition of the difference between C3 and C4 plants that I lifted off of Answers.Yahoo.com:
In C4 plants, carbon dioxide is drawn out of malate and into this reaction rather than directly from the air. Since every CO2 molecule has to be fixed twice, the C4 pathway is more energy consuming than the C3 pathway. The C3 pathway requires 18 ATP for the synthesis of one molecule of glucose while the C4 pathway requires 30 ATP. But since otherwise tropical plants lose more than half of photosynthetic carbon in photorespiration, the C4 pathway is an adaptive mechanism for minimizing the loss.”
In case you are like me, and have no idea what any of that means, Jacque’s description (and the IRRI poster we were shown) was far more useful. In essence, by changing rice from a C3 to a C4 plant carbon fixation would be far more efficient with regard to grain production, and plants would be potentially far less susceptible to droughts and other external stresses. This is because of significant increases in water use efficiency, nitrogen efficiency and radiation use efficiency for C4 plants. The bottom line is that more food can be grown to feed more people, on land of decreasing quality. And quite frankly, the way things are going, feeding the people we already have is going to be a problem. Land use changes and sea level inundations threaten some of the best land we have for agriculture, and that may be the biggest reason we will need to grow more food on less land, particularly in Asia. And rice feeds more people, especially those at the poverty level, than any other food source.
To be certain, the challenges are great for this project, and by Dr. Jacque’s own admission they haven’t a clue if they can succeed with this task or not. She figures it is a 20 year project with Phase 1 (just begun) being to reverse engineer certain C4 grasses (they are using sorghum) to see if there is a specific gene (or genes) that “turns on” the C4 pathway, and see if they can find the same genes in rice. The researchers believe that at some point in the evolution of C4 plants, some natural selection parameters caused previously C3 pathway plants to adapt to different environments, and perhaps there is a chance they can find out which vestigial plant parts might be responsible.
It is a huge task indeed, and to hear Jacque describe it, almost like finding a barley grain in a rice silo. The first step involves a series of chamber studies growing mutated sorghum plants under a variety of CO2 levels to look for signs that they have “turned off” the C4 pathway, which will help them to find out which gene or genes are responsible. We got to tour these experimental chambers at the end of a long day of meetings, and I am very thankful that they took the time to show us.
So why is a tree ring scientist interested in rice? Actually, the interest lies mostly with our post-doctoral fellow, Dr. Andrew Bell, who is working on the vulnerability modeling side of our Greater Mekong Basin grant. Andrew is using the long-term climate data provided by our tree ring network to analyze how the stresses of climate can manifest themselves into societal response. From the way we wrote the grant, we are primarily focused on the “megadroughts”, those periods of drought on the multi-decadal scale. In the near term, however, Andrew is working on developing simple models that may be of use to local small-scale farmers for decision-making on what to plant in any given year, using probabilities based on the past several centuries of tree-ring derived climate. The idea is to help farmers answer questions like, “If it was dry this year, what are the odds it’s going to stay dry next year? How about the year after?” So, we have been setting up meetings with folks like those at IRRI, and it was well worth the visit.
I first heard about IRRI as an undergraduate in the late 1970s at Plymouth State College in New Hampshire. My professor, Dr. Maynard Westin Dow (one of the most inspirational people I have ever known) invited the late Dartmouth Professor Robert Huke to speak to our class about his time at IRRI. It was there that the Green Revolution is credited with taking root, as new strains of high-yield rice were being developed that literally fed the world. I was captivated by Professor Huke’s presentation and I hoped that someday I would have the opportunity to visit this world-class institute. I am glad I finally did, and I urge anybody who is in the Philippines to visit IRRI (you can check out their web site here). It seems that rather than becoming an obsolete institution, the role of IRRI is as relevant as ever as we approach a set of new challenges under a changing climate in an increasingly degraded world.
It takes bold ideas to change the status quo. I think that this C4 Rice Project, whether it actually accomplishes its primary task or not, has the potential to lead to some really significant findings with regard to food production and plant sciences. We need equally bold thinking on a number of the problems we face, and that includes finding the funds to support primary research. Everything great that mankind has managed has come from these kinds of brash, almost arrogant sorts of approaches to tackling our problems. Whether or not one believes in anthropogenic global warming (AGW ), it should be clear that we face a boatload of problems with the environment we have inherited that are all somehow related to over population and to fossil fuel dependence of the billions of people we share this increasingly small planet with. We simply cannot conduct business as usual and expect the hammer not to fall at some point down the road.
So, with that in mind, I wish you all a Happy and safe Thanksgiving holiday if you are in the US, and a Happy and safe Loy Krathong if you are here in Thailand, and equal happiness and safety wherever you may be. It is with sadness that I note yet another tragic event that hit this region just last night, in Cambodia, where more than 300 people were killed while celebrating the Water Festival. The details are still sketchy, and the death toll rises, but it occurred on a bridge that connects an island in the confluence of the Mekong and Tonle Sap Rivers. It seems these types of tragedies occur all too frequently in this part of the world.