As anyone who's followed cancer research knows, the latest lab breakthrough can often take years before it finds applications in the real world (if it ever does). That's why a publication that should appear this week in PNAS was quite striking: not only did it describe the identification of a plant gene involved in drought resistance, but it included the results of putting that gene in a major agricultural crop, the rice plant. And the results were impressive: better tolerance of both drought and salt water.
The research started out in the plant most commonly used for genetic studies, Arabidopsis. A standard screen found a dominant mutation, which the researchers named HARDY, that produced slightly smaller, but more robust plants. The mutant plants also had the unusual property of being difficult to pull from the ground. Detailed characterization revealed that both the leaves and roots were significantly thicker than in normal Arabidopsis plants.
Dominant mutations are often caused by changes that increase the normal activity of a gene. So the authors reasoned that expressing more of the normal HARDY gene might have the same affect; they found that overexpression of the gene produced the same phenotype. The robust roots and leaves had a major consequence for the plant's water use: plants with excess HARDY could go up to 12 days without water and grow in 0.3 Molar salt solutions, conditions that killed their normal siblings.
HARDY turns out to encode a transcription factor, a type of protein that regulates the expression of other genes. Many proteins of this type have functions that are evolutionarily conserved even in distantly related species, so the authors posited that HARDY overexpression might have a similar effect in a variety of plants. They tested this on a major crop plant, rice. As with Arabidopsis, rice overexpressing the gene grew better under drought conditions, and made much more efficient use of water than normal plants.
The researchers note that growing populations and changing precipitation patterns have already placed great strains on the availability of water for irrigation, and that rice is a very water-intensive crop. Given that these water use pressures are expected to increase if global temperatures continue to rise, the identification of HARDY may be a major breakthrough, provided its manipulation is consistent with an efficient crop yield.
When published, the paper should appear here.
PNAS, 2007. DOI: 10.1073/pnas.0707294104