Your research focuses on the soybean symbiont Bradyrhizobium, which fixes nitrogen for the plant. I’ll play devil’s advocate here and ask, what can we learn about this symbiosis that will help agriculture? Isn’t it enough to know that the two players help each other out?
Let me back up and correct you: although my initial research was on Bradyrhizobium symbionts, I’d say that we’ve significantly broadened from that point.
But about Bradyrhizobium, the answer is yes, we can learn many helpful things about the symbiosis. There’s a product on the market now, for example, called “Optimize 400” and it appears to be doing well. It contains the lipo-chitin Nod factor, a signal produced by Bradyrhizobium that goes to the plant; this signal is critical for nodulation to occur. We characterized this molecule and patented it and now this company, EMD Crop Biosciences, actually sells it along with their commercial inoculant. They claim it has a significant effect on root growth and plant growth, so there’s one example of how our curiosity-driven research has actually aided agriculture.
Our goal was to understand the mechanisms of the Bradyrhizobium-soybean interaction, not to create a product, but here’s an example of where we’ve been able to translate a basic discovery into a commercial product. We continue to work with that thinking in mind – we try and understand the basic mechanisms, but at the same time we are always looking for discoveries that can have a practical benefit.
In 2002, your lab discovered and described bradyoxetin. What is the significance of this compound in symbiosis with Bradyrhizobium?
We made this discovery trying to understand why the nodulation genes in Bradyrhizobium could only be induced at very low culture density. This led to the discovery of bradyoxetin, which is a compound that accumulates in the medium of batch cultures. Bradyrhizobium represses the expression of the nodulation genes through a mechanism mediated by the NolA regulatory protein. These observations led us to propose that bradyoxetin was a quorum sensing molecule, functionally similar to the homoserine lactone molecules found in other bacteria. However, subsequently we found that bradyoxetin actually accumulates in batch cultures due to iron limitation and, therefore, in a strict sense is not a quorum signal. Still, bradyoxetin appears to be a key molecule in the regulation of the nodulation genes.
Where do you see your field in 10 years?
The holy grail in nitrogen fixation research for many years has been the ability to transfer biological nitrogen fixing ability from legumes to other plants, such as corn. I don’t think we’ll get there in 10 years, but we’re learning more and more about what’s required to form a symbiosis. Once we know enough it might become a possibility.
On the other hand, I think that more of the discoveries we’re making could have practical applications, like the Optimize product that I mentioned earlier.
If you had to change careers today and you could do anything, what would you do?
I actually feel quite fortunate to have chosen the career that I did. However, I clearly feel inadequate in some areas, especially mathematics and bioinformatics. Chemistry is another area where I feel that more formal training would have been useful. Therefore, I am not sure if I would totally change careers if given the chance but, if I had my education to do over again, I would likely strengthen my training in these other fields.
What’s your favorite science book?
I am afraid that I am going to duck this question. I have edited 14 books in my career so I will tell you that these are all my favorites. I read a lot of papers, reviews, and other technical literature, but not many science books. When I read a book it is either fiction or biography, something to enjoy and relax with.
What is something about you that most people don’t know?
There are probably a lot of things they don’t know. One of the more recent things that I am very proud of is that I was the founder and currently serve as the executive director of a not-for-profit corporation called the Missouri Energy Initiative. You can find out about it by going to www.moenergy.org.