Stomatal movement plays an important role in plant response to drought stress. Microfilament skeleton and abscisic acid (ABA) are crucial components involved in this process. However, little is known about the remodeling mechanism of microfilament skeleton and the dynamic changes of stomatal movement in response to drought stress/ABA signals. Microfilament depolymerization factor (ADF) is a conserved microfilament cleavage/depolymerization protein in eukaryotes. In angiosperms, ADF has evolved microfilament bunching activity. It was found that drought stress and ABA treatment could induce the transcriptional expression of ADF5 in Arabidopsis thaliana. In addition, the loss of ADF5 function resulted in an increase in water loss from detached leaves and a decrease in survival rate after drought stress, resulting in delayed stomatal closure. Biochemical analysis showed that ABF/AREB transcription factor DPBF3 could bind to ADF5 promoter and activate its transcription.

In conclusion, the results suggest that ADF5 participates in drought stress by regulating stomatal closure, mediated by ABF/AREB transcription factor family as a potential downstream target of drought stress/ABA signaling pathway. The paper entitled “Arabidopsis ADF5 promotes stomatal closure by regulating actin cytoskeleton remodeling in response to ABA and drought stress” was published in Journal of Experimental Botany in November 2018.