PLANT U-BOX PROTEIN 10 negatively regulates abscisic acid response in Arabidopsis

MYC2 is well known as a positive regulator for abscisic acid (ABA) signaling but whether PLANT U-BOX PROTEIN 10 (PUB10) is involved in ABA responses has not been reported. Here, we show that the E3 ubiquitin ligase PUB10 modulates ABA signaling in Arabidopsis. PUB10ox (35S:PUB10-myc) and myc2 loss-of-function mutants were hyposensitive to ABA during germination, whereas pub10 loss-of-function and MYC2ox (35S:MYC2-GFP) mutants were hypersensitive. In addition, pub10 mutants showed hypersensitivity to high salt and osmotic stress during germination; by contrast, PUB10ox line displayed the opposite phenotype. ABA-induced expression of KIN2 (Cold- and ABA-Inducible Protein), RD22 (Responsive to Dehydration 22), ANAC019 (NAC Domain-Containing Protein 19), and ANAC055 (NAC Domain-Containing Protein 55) was enhanced in both pub10 and MYC2ox plants. Taken together, pub10 plants phenocopied MYC2ox plants, whereas PUB10ox plants phenocopied myc2 in ABA response. Our results provide evidence that PUB10 negatively regulates ABA signaling in Arabidopsis.