Regulation of Pre-rRNA Processing in Plant: Mechanisms, Plasticity, and Developmental Implications

Ribosome biogenesis is a fundamental process underlying plant growth, development, and environmental adaptation, and processing of precursor rRNA (pre-rRNA) represents one of its most critical regulatory steps. This review provides a systematic overview of the multi-layered regulatory mechanisms controlling pre-rRNA processing in plants, with Arabidopsis thaliana as the primary model system. We focus on the genomic organization of ribosomal DNA (rDNA) and its epigenetic regulation, illustrating how highly repetitive and sequence-diverse rDNA arrays maintain genomic stability while enabling tissue-specific expression of distinct rDNA variants. We further summarize the dynamic pathways of pre-rRNA processing and their plastic regulation under environmental conditions such as elevated temperature. In addition, we review the quality control systems that monitor pre-rRNA maturation, including non-templated tailing and exonuclease-dependent degradation pathways, which play essential roles in removing aberrant processing intermediates. We further examine how perturbations in pre-rRNA processing give rise to plant ribosomopathies and discuss complementary models of ribosome homeostasis and ribosome heterogeneity as frameworks for interpreting shared developmental phenotypes. Finally, by synthesizing genetic and molecular evidence, we highlight the pivotal role of pre-rRNA processing in orchestrating plant development and propose directions for future research.