Crop engineering: Hijacking hormone receptors

Nature http://doi.org/2bj (2015)

When faced with a scarcity of water, plants adopt a series of measures to preserve water and increase their tolerance to stress, such as closing their stomata. These various responses are controlled through abscisic acid (ABA). By engineering an ABA receptor to respond to the chemical mandipropamid, Sang-Youl Park of the University of California, Riverside, and colleagues have demonstrated an approach to manipulating these natural responses to better serve the needs of agriculture.

The researchers first tested a library of mutants of the ABA receptor PYRABACTIN RESISTANCE 1 (PYR1) for sensitivity to a panel of common agrochemicals. They found that a mutant, PYR1^MANDI, containing changes in six amino acid residues lining the receptor's ABA binding pocket was selectively activated by nanomolar concentrations of the fungicide mandipropamid.

Mandipropamid treatment of transgenic Arabidopsis plants expressing PYR1^MANDI induced a systemic response mimicking that produced by ABA including inhibition of seed-germination, retardation of root-growth, changes in transpiration rate and genome-wide transcriptional reprogramming. Moreover, mandipropamid application increased the survival of the plants under water shortage.

Tomato plants expressing PYR1^MANDI also showed reduced transpiration rates when treated with mandipropamid suggesting that engineered ABA receptors could prove a promising route to producing drought tolerant crops.