James and the Giant Corn Genetics: Studying the Source Code of Nature

January 6, 2010

Biodiversity and Genetic Engineering Aren’t Mutually Exclusive!

Filed under: Feeding the world,Plants — Tags: , , , — James @ 8:28 pm

The work of plant breeders and the naturalists who catalog so much of the genetic diversity passed down over 400 generations*, have done far more to feed people than genetic engineering thus far. The reason I spend so much time talking about genetic engineering (and to a lesser extent mutation breeding) isn’t because I think the techniques are more important than breeding using the existing diversity of crop plants and their wild ancestors, it’s because genetic engineering (and once more to a lesser extent mutation breeding) are the techniques that are subject to the most misinformation and opposition. If I had to choose, for the entire world, between marker assisted selection and genetic engineering, I’d choose marker assisted selection in a heartbeat. But we don’t have to chose.

Consider three cases:

  1. The submergence tolerant rice that’s now being distributed to farmers in Bangladesh could NOT have been made without the collection and study of the wild weedy rice in the first place. And while the gene responsible for the trait was first identified using a transgenic approach, the final rice was produced using only marker assisted breeding. Sub1 rice needed natural biodiversity, and it didn’t need genetic engineering.
  2. A single protein P34 (a cysteine protease) is responsible for the allergic reaction of a majority of the people who can’t eat soy. Both genetic engineering and natural biodiversity offer ways to develop plant breeds without a functional copy of a specific gene. In this case researchers (lead by Herman Elliot and Ted Hymowitz) opted to screen over 10,000 lines of soybeans collected from around the world by USDA naturalists, and found two which carried a null allele for the gene.** [Herman Elliot’s paper]
  3. Golden rice (which may, someday, get past the expensive regulatory hurdles placed before it) was created (and refined) using genetic engineering. It was created after plant breeders like Peter Jennings [one of the creators of IR8 rice***] had spent decades unsuccessfully searching the world for some variety of rice with yellow grains, indicating the production of pro-vitamin A. Golden rice would be impossible without genetic engineering.

It may be that genetic engineering has been used as an excuse by politicians who are reluctant to part with the money needed to fund seed banks, but I don’t know of ANY scientists who think genetic engineering renders seed banks obsolete.

*The first evidence of agriculture is roughly 10,000 years ago. Assume an average human generation was 25 years for most of that time. The oldest family lines of farmers stretch back through four hundred fathers and sons, mothers and daughters.

**A null allele is a verson of the gene that doesn’t function, either because the gene is never made into protein, or because a mutation has changed the protein so much it is completely unable to function. The two most common mutations that create null alleles are premature stop codons: the protein stops getting made partway through, and frameshift mutations: insertions or deletions that aren’t divisible by three. Since genes are written in a language of three letter long words without any separation between words, it the same effect as shifting around the spaces in a sentence (here I’ve deleted the “h” in “which” but kept the spaces as they would be without the deletion):

Whici sa g oodw ayt ow riteg ibberish.

***IR8 was one of the new rice breeds that sparked the green revolution, among other things helping the Philippines becomes rice self-sufficient.

In 1966, a young Indian IRRI agronomist, S. K. De Datta, tested the IR8 variety under different fertilizer conditions. He was amazed with the results – the IR8 rice produced around 5 tons per hectare with no fertilizer and rose to almost 10 tons with 120 kg of nitrogen per hectare. That was 10 times the traditional rice yield.


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