Development of Drought‐Tolerant Canola ( Brassica napus L.) through Genetic Modulation of ABA‐mediated Stomatal Responses

Canola is one of the most important oilseed crops, and its seed yield and quality are significantly affected by environmental stresses such as drought. The phytohormone abscisic acid (ABA) is induced by drought and triggers stomatal closure to reduce transpiration, which accounts for >90% of water loss in plants. The ABA‐mediated stomatal response is a dosage‐dependent process that can be achieved by either increasing the endogenous ABA concentration or by sensitizing the responsiveness of guard cells to the hormone. We summarize the recent breakthroughs in the understanding of key molecular components that regulate the homeostasis and sensing of ABA, and their potential applications in genetic engineering for drought tolerant canola. In particular, the α and β subunits of protein farnesyltransferase have been identified as negative regulators of ABA‐mediated stomatal responses, and their effectiveness as the targets for engineering drought tolerance and yield protection has been confirmed in canola in the field. Further development of the drought stress tolerance property in the crop will likely have a fundamental impact on its productivity in many regions of the world.