The old nourishes the new: 100 years of leaf senescence studies in Plant Physiology.

Abstract

The remarkable efficiency of plants is exemplified by leaf senescence, in which older leaves slowly perish while catabolizing and exporting the nutrients that made them prolific photosynthetic factories. Several endogenous (eg ontogeny and phenology) and exogenous (eg environmental stressors) factors can induce this physiological process. These multiple pathways, together with their complex regulatory networks, make senescence challenging to understand. The coordination between organelles, cells, and organs, across multiple levels of regulation (eg, genetic, metabolic, and physiological), further complicates the identification of the signals that initiate this process and the associated transduction pathways. Nevertheless, unraveling this complexity has remained a significant goal for plant biologists. The critical process of leaf senescence has been studied in Plant Physiology for 100 years. Research has focused on 6 main questions: (i) Which hormones regulate leaf senescence? (ii) How is highly abundant Rubisco catabolized? (iii) How do reproductive sinks regulate leaf senescence? (iv) How does photosynthesis change during leaf senescence? (v) What role do reactive oxygen species (ROS) play in leaf senescence? and (vi) How does gene expression change during leaf senescence? This review focuses on Plant Physiology's long-standing track record of publishing the foundational, field-defining work that has shaped core conceptual advances in leaf senescence research and provides context for future studies that will continue to address how leaves slowly and productively end their lives. Many other contributing papers have been cited in this review; however, our coverage is incomplete. We suggest readers view additional reviews for a more complete understanding of leaf senescence (Woo HR, Kim HJ, Lim PO, Nam HG. 2019. Leaf senescence: systems and dynamics aspects. Annu Rev Plant Biol. 70:347-376; Guo Y et al. 2021. Leaf senescence: progression, regulation, and application. Mol Hortic. 1:5; Zhang Y-M, Guo P, Xia X, Guo H, Li Z. 2021. Multiple layers of regulation on leaf senescence: new advances and perspectives. Front Plant Sci. 12:788996; Cao J, Liu H, Tan S, Li Z. 2023. Transcription factors-regulated leaf senescence: current knowledge, challenges and approaches. Int J Mol Sci. 24:9245; Zhai Y, Qiao W, Yang W, Liu X. 2026. Regulatory network of leaf senescence in Arabidopsis: the roles of transcription factors and microRNAs. Int J Mol Sci. 27:3584).