Researchers at the RIKEN Center for Sustainable Resource Science (CSRS) have discovered a new, yet simple, way to increase drought tolerance in a wide range of plants. Published in Nature Plants, the study reports a newly discovered biological pathway that is activated in times of drought. By working out the details of this pathway, scientists were able to induce greater tolerance for drought-like conditions simply by growing plants in vinegar.
Led by Jong-Myong Kim and Motoaki Seki at RIKEN CSRS, the large collaborative effort began with the discovery of novel Arabidopsis mutants that have strong drought tolerance, although the reasons were unknown. These plants have a mutation to an enzyme called HDA6 (histone deacetylase6), and the first goal of the current study was to determine exactly how this mutation allows the plants to grow normally in severe and extended conditions without water.
Kim and Seki say that this project has led to several important discoveries. Not only did they discover that external application of vinegar can enhance drought tolerance in the Arabidopsis plant, but they also found that this pathway is regulated epigenetically and conserved in common crops such as maize, rice, and wheat.
Initial testing in normal Arabidopsis under drought stress showed that genomic-wide expression of hda6 was linked to activation of the biological pathway that produces acetate, the main component of vinegar. In the mutated plants, they found that under the same conditions, this pathway was activated even more, and plants produced larger amounts of acetate. Further analysis showed that activity of the HDA6 enzyme acts as a switch that controls which type of metabolic pathway is active. Normally plants break down sugar for energy, but in time of drought, they switch to the acetate-producing pathway.
The team next measured acetate levels in normal plants and found that the amount of acetate produced by plants during drought directly correlated to how well they survived. To confirm this, they tested plants with mutations in two of the genes found in the acetate-biosynthesis pathway. Results showed that these plants produced less acetate and were more sensitive to drought than normal plants.