The endosomal sorting complex protein FYVE4 affects abscisic acid signaling by regulating the stability of abscisic acid receptors

The abundance of PYR/PYL/RACR-type abscisic acid (ABA) receptors can be modulated through transcriptional regulation, ubiquitination-mediated degradation, and protein expression level, which directly influences the intensity and efficiency of the ABA signaling pathway. Here, we report that the FYVE domain-containing protein FYVE4, a plant-specific component of the Endosomal Sorting Complex Required for Transport III (ESCRT-III), negatively modulates ABA signaling. In this study, we showed that FYVE4 directly binds to ABA receptors, overexpression of FYVE4 promotes its degradation, and impaired FYVE4 function leads to the accumulation of ABA receptor PYL4. In line with this, the loss-of-function fyve4-1 mutants display hypersensitivity to ABA treatment during plant growth as well as a corresponding stomatal closure phenomenon and a more drought-tolerant phenotype, enriching the role of the plant ESCRT machinery in the regulation of water loss of stomatal control induced by ABA signaling. Taken together, our results suggest that FYVE4 affects ABA signaling through regulating PYL4 degradation, providing a deeper understanding of the role of the ESCRT complexes in studying adverse stresses.