Regulatory Mechanisms of Leaf Senescence in Herbaceous and Woody Perennials: A Comparative Review

Leaf senescence in perennial species constitutes a highly orchestrated developmental phase that differs fundamentally from the obligate monocarpic senescence of annual plants. While individual organs undergo programmed senescence, prerennial organisms maintain longevity across multiple growing seasons through a sophisticated interplay between endogenous programs and exogenous cues. This review provides a systematic synthesis of the regulatory mechanisms governing leaf senescence in herbaceous perennials (Lolium perenne and Festuca arundinacea) and woody perennials (Populus, Pinus, and Agave). We highlight a multi-layered regulatory landscape, encompassing divergent and conserved pathways in transcriptional orchestration, hormonal crosstalk, metabolic reprogramming, and telomere maintenance. Specific emphasis is placed on how these mechanisms allow for tissue-specific and seasonal adaptation, such as the integration of dormancy signals in woody taxa versus stress-plasticity in perennial grasses. By elucidating these complex frameworks, this review not only advances our fundamental understanding of plant life-span regulation but also provides a theoretical foundation for the molecular breeding of delayed senescence germplasm, offering transformative potential for enhancing agricultural productivity and ecological resilience.