Natural variations of ZmSRO1d modulate the trade-off between drought resistance and yield by affecting ZmRBOHC-mediated stomatal ROS production in maize

While crop yields have historically increased,drought resistance has become a major concern in the context of global climate change.The trade-off between crop yield and drought resistance is a common phenomenon;however,the underlying molecular modulators remain undetermined.Through genome-wide association study,we revealed that three non-synonymous variants in a drought-resistant allele of ZmSRO1d-R resulted in plasma membrane localization and enhanced mono-ADP-ribosyltransferase activity of ZmSRO1d toward ZmRBOHC,which increased reactive oxygen species(ROS)levels in guard cells and promoted stomatal closure.ZmSRO1d-R enhanced plant drought resilience and protected grain yields under drought conditions,but it led to yield drag under favorable conditions.In contrast,loss-of-function mutants of ZmRBOHC showed remarkably increased yields under well-watered conditions,whereas they showed compromised drought resistance.Interestingly,by analyzing 189 teosinte accessions,we found that the ZmSRO1d-R allele was present in teosinte but was selected against during maize domestication and modern breeding.Collectively,our work suggests that the allele frequency reduction of ZmSRO1d-R in breeding programs may have compromised maize drought resistance while increased yields.Therefore,introduction of the ZmSRO1d-R allele into modern maize cultivars would contribute to food security under drought stress caused by global climate change.