Ribosome Heterogeneity in Plants: The Causes of This Phenomenon and Its Implications on Gene Expression

Ribosomes are essential macromolecular complexes responsible for protein synthesis and have traditionally been regarded as uniform and passive components of translational machinery. However, accumulating evidence has revealed that ribosomes exhibit substantial heterogeneity in both composition and function. In this review, we summarize the major sources of ribosome heterogeneity in plants, including ribosomal protein (RP) paralog diversity, sequence variation in rDNA/rRNA, dynamic chemical modifications of rRNAs and RPs, alterations in RP stoichiometry, and the involvement of ribosome-associated factors. These mechanisms collectively generate structurally and functionally distinct ribosome populations. Emerging evidence suggests that these heterogeneous ribosomes can actively regulate gene expression by preferentially translating specific subsets of mRNAs in response to developmental cues and environmental conditions. We further discuss the potential biological implications of ribosome heterogeneity in plant growth, development, and stress adaptation, and highlight current challenges in the field. Advances in high-resolution structural and single-ribosome profiling technologies are expected to provide new insights into the regulatory roles of heterogeneous ribosomes. This review provides a comprehensive framework for understanding the causes and functional significance of ribosome heterogeneity in plants, offering new perspectives on translational regulation and plant adaptive biology.