Arabidopsis U‐box E3 ubiquitin ligase PUB11 negatively regulates drought tolerance by degrading the receptor‐like protein kinases LRR1 and KIN7

Abstract

Both plant receptor‐like protein kinases (RLKs) and ubiquitin‐mediated proteolysis play crucial roles in plant responses to drought stress. However, the mechanism by which E3 ubiquitin ligases modulate RLKs is poorly understood. In this study, we showed that Arabidopsis PLANT U‐BOX PROTEIN 11 (PUB11), an E3 ubiquitin ligase, negatively regulates abscisic acid (ABA)‐mediated drought responses. PUB11 interacts with and ubiquitinates two receptor‐like protein kinases, LEUCINE RICH REPEAT PROTEIN 1 (LRR1) and KINASE 7 (KIN7), and mediates their degradation during plant responses to drought stress in vitro and in vivo. pub11 mutants were more tolerant, whereas lrr1 and kin7 mutants were more sensitive, to drought stress than the wild type. Genetic analyses show that the pub11 lrr1 kin7 triple mutant exhibited similar drought sensitivity as the lrr1 kin7 double mutant, placing PUB11 upstream of the two RLKs. Abscisic acid and drought treatment promoted the accumulation of PUB11, which likely accelerates LRR1 and KIN7 degradation. Together, our results reveal that PUB11 negatively regulates plant responses to drought stress by destabilizing the LRR1 and KIN7 RLKs.

Plant E3 Ligases and Their Role in Abiotic Stress Response

“…Many members of PLANT U BOX (PUB) E3 ligases have been shown to be involved in drought stress tolerance regulation ( Table 1 ). In Arabidopsis, PUB11 negatively regulates drought stress response by targeting LEUCINE RICH REPEAT PROTEIN 1 (LRR1) and KINASE 7 (KIN7) for degradation via the 26S proteasome [ 67 ]. Both LRR1 and KIN7 are needed to promote stomatal closure during water stress conditions [ 172 , 173 ].…”

“…These E3 ligases also function as monomeric E3s and encompass less than 100 members in plants [ 54 , 55 , 56 , 57 ]. They function widely in abiotic and biotic stress responses, but have also been described, for example, in apical meristem maintenance or phytohormone signaling [ 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 ].…”

Identification of Key Genes in ‘Luang Pratahn’, Thai Salt-Tolerant Rice, Based on Time-Course Data and Weighted Co-expression Networks

“…In Arabidopsis, it was reported that two receptor-like kinases, LRR1, and KIN7 are targeted by PLANT U-BOX PROTEIN 11 (PUB11), an E3 ubiquitin ligase, and lead to their degradation during drought stress. This is regulated through abscisic acid ( Chen et al, 2021c ). The receptor-like protein kinase HAIKU2 is a type of leucine-rich receptor-like protein kinase (LRR-RLK).…”

Exploitation of Drought Tolerance-Related Genes for Crop Improvement

“…Protein degradation is also a way for crop plants to adapt to drought stress. For example, the E3 ubiquitin ligase gene is involved in protein degradation during drought stress, which includes several subfamilies: (1) RING finger gene family members OsDSG1 [ 109 ], OsRDCP1 [ 110 ], OsSDIR1 [ 111 ], StRFP2 [ 112 ], and TaSDIR1 [ 113 ]; (2) U-box gene family member PUB11 [ 114 ]; (3) F-box gene family members SAGL1 and ECERIFERUM3 [ 115 ]; and (4) CUL4-DDB1 gene family member HOS15 [ 116 ].…”

“…[109], OsRDCP1[110], OsSDIR1[111], StRFP2[112], and TaSDIR1[113]; (2) U-box gene family member PUB11[114]; (3) F-box gene family members SAGL1 and ECERIFERUM3[115]; and (4) CUL4-DDB1 gene family member HOS15[116].…”