Arabidopsis E3 Ubiquitin Ligases PUB22 and PUB23 Negatively Regulate Drought Tolerance by Targeting ABA Receptor PYL9 for Degradation.
Drought causes osmotic stress and rapidly triggers abscisic acid (ABA) accumulation in plants. The roles of various ABA receptors in drought tolerance and molecular mechanisms regulating ABA receptor stability needs to be elucidated. Here, we report that Arabidopsis plants overexpressing PYL9, one of the 14 pyrabactin resistance (PYR)/pyrabactin resistance-like (PYL)/regulatory component of ABA receptors (RCAR) family ABA receptors, gained drought tolerance trait. Osmotic stress induced accumulation of the PYL9 protein, which was regulated by the 26S proteasome. PYL9 interacted with two highly homologous plant U-box E3 ubiquitin ligases PUB22 and PUB23. In the cell-free degradation assay, the degradation of GST-PYL9 was accelerated in protein extract from plants overexpressing PUB22 but slowed down in protein extract from the pub22 pub23 double mutant. The in vivo decay of Myc-PYL9 was significantly reduced in the pub22 pub23 double mutant as compared with the wild-type. Additionally, PUB22 also interacted with other ABA receptors such as PYL5, PYL7 and PYL8. Considering the improved drought tolerance in the pub22 pub23 double mutant in previous studies, our results suggest that PUB22 and PUB23 negatively regulate drought tolerance in part by facilitating ABA receptors degradation.
['Zhao|Jinfeng|J|', 'Zhao|Linlin|L|', 'Zhang|Ming|M|', 'Zafar|Syed Adeel|SA|', 'Fang|Jingjing|J|', 'Li|Ming|M|', 'Zhang|Wenhui|W|', 'Li|Xueyong|X|']
D000220:Adaptation, Biological D017360:Arabidopsis D029681:Arabidopsis Proteins D002352:Carrier Proteins D055864:Droughts D015870:Gene Expression D047908:Intracellular Signaling Peptides and Proteins D009997:Osmotic Pressure D010641:Phenotype D046988:Proteasome Endopeptidase Complex D011485:Protein Binding D055550:Protein Stability D059748:Proteolysis D013312:Stress, Physiological D044767:Ubiquitin-Protein Ligases
drought tolerance ABA receptor degradation U-box E3 Ubiquitin ligases cell-free degradation assay protein extract