Upregulation of a proton-pyrophosphatase as a strategy to engineer drought-resistant crops

This paper comes from the lab of MIT Biology Professor Gerald Fink and presents a novel, widely applicable method of engineering drought-resistant crops. The paper's abstract is copied below, followed by an overview intended for an audience of non-biologists. "Engineering drought-resistant crop plants is a critically important objective. Overexpression of the vacuolar H+-pyrophosphatase (H+-PPase) AVP1 in the model plant Arabidopsis thaliana results in enhanced performance under soil water deficits. Recent work demonstrates that AVP1 plays an important role in root development through the facilitation of auxin fluxes. With the objective of improving crop performance, we expressed AVP1 in a commercial cultivar of tomato. This approach resulted in (i) greater pyrophosphate-driven cation transport into root vacuolar fractions, (ii) increased root biomass, and (iii) enhanced recovery of plants from an episode of soil water deficit stress. More robust root systems allowed transgenic tomato plants to take up greater amounts of water during the imposed water deficit stress, resulting in a more favorable plant water status and less injury. This study documents a general strategy for improving drought resistance of crops." Vacuoles are large chambers within plant cells that are used to store water. If the salt concentration inside a vacuole is relatively high, the vacuole will absorb a greater volume of water via osmosis, meaning more water will be stored within individual plant cells in the case of drought. Overexpression of the H+-PPase, an ion pump, causes more salt to be pumped into the vacuoles, increasing total water retention and hence drought-resistance. This strategy for engineering drought-resistant plants is applicable well beyond Arabidopsis thaliana and tomatoes, the plants directly studied in this paper.