Last month, I wrote a post about a research group at Texas A&M University that reported genetically engineering "edible cotton seeds" by using RNAi technology to stably and specifically knock out production of the gossypol toxin in the seeds of the plant. I thought that the paper was interesting for a variety of reasons, including the use of RNAi and the fact that this was a novel usage of transgenic crop biotechnology coming from an academic group. I recently contacted the study's leader, Dr. Keerti Rathore, to ask him a couple of questions in hopes of further understanding the implications of his study.
On the scientific side of things, I had mentioned that I thought the use of RNAi to produce a stable phenotype was interesting, since (as a molecular biologist) I tend to think of RNAi as a technique used to temporarily reduce the level of a targeted gene product. Rathore tells me, though, that this is a standard application of RNAi in his field and that one would use it to produce transgenic crops similarly to how one would use any other method. "So, just as you would do for a traditional transgenic trait (e.g. Bt-corn)," Rathore said, "you need to produce a large number of RNAi lines and follow them over several generations in the greenhouse and later in the field." Some of these will lose the desired trait, but others will maintain the transgenic phenotype generation after generation, and "these are the lines that finally become products that can be used by the farmers."
I had also noted that Rathore previously explained to me (in April 2005) that university-based transgenic crop research serves an important role in the otherwise corporate-dominated area of transgenic crops by focusing on the types of transgenic crops needed by the developing world and putting the technology into the hands of small farmers instead of large agricultural corporations. When I asked him whether the fact that the "edible cotton seeds" were produced through academic research was significant, Rathore assured me that this is still the case. "Companies will never take up this kind of research because they cannot figure out a way to make any money from this type of product," he told me.
As far as plans to put his new crop technology to use, "We are working to figure out how to move forward," Rathore said. "A lot of patented technologies are involved in creating these plants and also the cost of meeting the regulatory approvals is huge. This will take time."
I'm new to reading your blog, but I'm pretty interested in science and I really like it. I've been looking over a lot of your archives and such, and I think it's pretty cool. Anyway, I don't understand molecular biology super well. In this post you say that certain lines of the plants would lose the characteristics that make them not edible, and others would eventually get them back. If the cells are changed why would that trait come back?
Thanks for your blog.
I don't know much about this area, but Rathore called the phenomenon "silencing". Basically, some lines adapt early on to the new trait and evolve ways of covering up the trait. Those that don't silence the trait early on, though, seem to carry the trait on for many generations, enough to be useful agriculturally.
Edible cotton seeds? What next, potable sorghum? Perhaps you could do some research and give us a report.