Gain‐ and loss‐of‐function mutations in <i>Zat10</i> enhance the tolerance of plants to abiotic stress

C 2 H 2 ‐zinc finger proteins that contain the EAR repressor domain are thought to play a key role in modulating the defense response of plants to abiotic stress. Constitutive expression of the C 2 H 2 ‐EAR zinc finger protein Zat10 in Arabidopsis was found to elevate the expression of reactive oxygen‐defense transcripts and to enhance the tolerance of plants to salinity, heat and osmotic stress. Surprisingly, knockout and RNAi mutants of Zat10 were also more tolerant to osmotic and salinity stress. Our results suggest that Zat10 plays a key role as both a positive and a negative regulator of plant defenses.