Crosstalk and reciprocal regulation of phosphorylation and ubiquitination mediated by receptor-like kinases and U-box E3 ligases during plant growth and environmental stress responses.

Plant growth and environmental adaptation rely on the precise regulation of signal transduction, in which phosphorylation and ubiquitination serve as key post-translational modifications (PTMs). Receptor-like kinases (RLKs) and plant U-box E3 ligases (PUBs) constitute a core module that regulates crosstalk between these modifications to fine-tune plant development and stress responses. This module governs diverse biological processes, including plant immunity through regulation of pattern recognition receptors (PRRs), growth and development such as root architecture and nodulation, reproduction via self-incompatibility (SI), and abscisic acid (ABA) signaling/drought tolerance through modulation of key signaling components. It also provides insights into the reciprocal regulatory mechanisms between RLKs and PUBs and the role of RLK-PUB modules in maintaining cellular homeostasis. Here, we summarize the current understanding of RLK-PUB modules in coordinating phosphorylation-ubiquitination crosstalk at both genetic and molecular levels during plant growth and stress responses. Additionally, we discuss potential regulatory models for RLK-PUB modules whose mechanisms remain unresolved and highlight key questions that warrant further investigation.