Crosstalk and reciprocal regulation between 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 precise regulation of signal transduction, in which phosphorylation and ubiquitination play critical roles as post-translational modifications (PTMs). Receptor-like kinases (RLKs) and plant U-box E3 ligases (PUBs) constitute a core regulatory module that mediates crosstalk between these modifications to fine-tune plant responses. This module governs diverse biological processes, including plant immunity via regulating pattern recognition receptors (PRRs), growth and development such as root architecture and nodulation, reproduction through self-incompatibility (SI) mechanisms, and ABA signaling/drought tolerance by modulating key signal components. It also provides insights into reciprocal regulatory mechanisms between RLKs and PUBs, and the role of RLK-PUB module in maintaining cellular homeostasis. Here, we summarize the current understanding of RLK-PUB modules in coordinating phosphorylation-ubiquitination crosstalk at the genetic and molecular levels during plant growth and environmental stress responses. Additionally, the possible molecular regulatory patterns of those RLK-PUB modules with unrevealed mechanisms are discussed. We also point out the thought-provoking questions raised by the research on these plant RLK-PUB modules for future investigation.