C. L. Casteel

Global climate change is causing more frequent and severe droughts, which can have negative impacts on plant growth and crop productivity. Under drought conditions, plants produce the hormone ABA (abscisic acid), which regulates adaptive responses, such as stomatal closure and root elongation. Plant viruses have been used in the lab to convey new traits to plants and could also be used to increase production of ABA or to enhance downstream plant drought resistance responses. In this study, foxtail mosaic virus (FoMV) was used to silence ZmPP2C‐A10 , a negative regulator of ABA signalling, in maize ( Zea mays L.). Both silenced and control plants were exposed to an 8‐day drought treatment, followed by a 30‐day period of rewatering, after which indicators of drought resistance were measured. After drought treatment, we observed a nearly twofold increase in expression of a stress‐mitigation gene, ZmRAB17 , reduced chlorophyll fluorescence changes (indicator of stress), and increased plant biomass and development in the ZmPP2C‐A10‐ silenced maize compared to controls. These results demonstrate that the FoMV system can be used to silence endogenous expression of ZmPP2C‐A10 and increase maize tolerance to drought. This could offer a useful tool to improve crop traits and reduce yield loss during the growing season.