ABA levels in the plant greatly increase in response to water stress, resulting in the closure of stomata thereby reducing the level of water loss through transpiration from leaves and activate stress response genes. The reaction is reversible: once water becomes available again, the level of ABA drops, and stomata re-opens. Increasing the plant’s sensitivity to ABA has therefore been a very important target for improving drought tolerance.
ERA1, a gene identified in Arabidopsis, encodes the ß-subunit of a farnesyl-transferase, and is involved in ABA signaling. Plants lacking ERA1 activity have increased tolerance to drought, however are also severely compromised in yield. In order to have a conditional, reversible down-regulation of ABA, a group of Canadian researchers used a drought-inducible promoter to drive the antisense expression of ERA1, in both Arabidopsis and canola plants11. Transgenic plants performed significantly better under water stress, with consistently higher yields over conventional varieties. Importantly, there was no difference in performance between transgenic and controls in conditions of sufficient water, demonstrating that the technology has no yield-drag11. Multi-location trials have confirmed yield increases due to enhanced protection to drought to be 15-25 percent compared to non-transgenic controls (http://www.performanceplants.com).
Performance Plants Inc, a Canadian plant biotechnology company, is developing the technology for commercialization, under the name Yield Protection Technology™ (YPT™). YPT™ is also being developed for maize, soybean, cotton, ornamentals and turf grass to be available to farmers in early 2011