2. Academic Validation
  3. Degradation of PbrDGK4 impairs pollen tube endocytosis in pear self-incompatibility by reducing PbrAP1/2β phosphorylation

Degradation of PbrDGK4 impairs pollen tube endocytosis in pear self-incompatibility by reducing PbrAP1/2β phosphorylation

  • New Phytol. 2026 May;250(3):1669-1688. doi: 10.1111/nph.71018.
Xiao-Xiong Kong 1,  Chao Tang 2,  Li-Hua Zhai 1,  Tao Chen 1,  Li-Yu Gao 1,  Jing Zhang 1,  Xiao Liu 1,  Zhi-Ping Zhang 1,  Ju-You Wu 2,  Chun-Lei Wang 1
Affiliations

Affiliations

  • 1 College of Horticulture and Landscape Architecture, International Research Laboratory of Agriculture and Agri-Product Safety, Key Laboratory of Plant Functional Genomics of the Ministry of Education, Yangzhou University, Yangzhou, 225009, China.
  • 2 Jiangsu Engineering Research Center for Pear, State Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing, 210014, China.
PMID: 41735043 DOI: 10.1111/nph.71018
Abstract

Pear (Pyrus bretschneideri) self-incompatibility (SI) is an S-RNase-based system that arrests incompatible pollen tube growth, but the molecular mechanism by which SI regulates endocytosis (a key process for pollen tube polarity) remains unclear. Live-cell imaging, Phos-tag immunoblots, molecular docking, gene silencing, mutant complementation, and ubiquitination assays were combined to dissect the regulatory pathway. Incompatible S-RNase impairs clathrin-mediated endocytosis (CME). The AP-1/AP-2 shared β-subunit PbrAP1/2β is essential for CME, with Ser228 phosphorylation enhancing AP-2 complex stability. Pollen tube-specific kinase PbrDGK4 maintains PbrAP1/2β phosphorylation via interaction. SI-induced E3 Ligase PbrARI2.3 mediates K48-linked ubiquitination (K60/K254) and degradation of PbrDGK4, reducing PbrAP1/2β phosphorylation. S-RNase triggers PbrDGK4 degradation, lowering PbrAP1/2β Ser228 phosphorylation and impairing CME, ultimately arresting incompatible pollen tube growth, advancing insights into SI-regulated pollen tube polarity.

Keywords

K48‐linked ubiquitination; Pear; adaptor protein complexes; diacylglycerol kinase; endocytosis; phosphorylation; self‐incompatibility.

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