Plant Programmed Cell Death

Abstract

Programmed cell death (PCD) is a fundamental biological process in plant cells. Indeed, all multicellular organisms need a cellular death process to be able to regulate cell numbers, to direct developmental processes, defend themselves against pathogens or to eliminate unwanted or damaged cells. In plants, PCD is governed by genetic signals and environmental cues and operates from the embryogenic beginning of a plants' life to the final whole plant death processes. The study of PCD is an expanding discipline in plant sciences as an understanding of the core regulatory processes involved in plant PCD may facilitate breeding programmes that modify the timing or intensity of PCD events. The ability to breed for a more efficient PCD may have a profound impact on our capacity to support crop species and maintain yields, in rapidly changing environments. This article reviews the methods used to study PCD in plants and outlines our current understanding of PCD regulation. Key Concepts Programmed cell death (PCD) is a fundamental process in plants. It is involved in defence, development and response to stress. Regulation of PCD is genetic with a significant role played by environmental stimuli. Plant programmed cell death has many similarities to animal apoptosis – chromatin and nDNA fragmentation, cell shrinkage, contraction of the cytoplasm, mitochondrial swelling and release of mitochondrial‐based proteins. Plants have unique cellular components – cell walls, chloroplasts and a large central vacuole – which play roles in plant PCD. Retraction of the protoplast during PCD results in a distinctive morphology that can be used as a quantifiable reporter of PCD. Reactive oxygen species (ROS) play a role in the induction, signalling and execution of plant PCD. Fine tuning of ROS governs PCD responses to stress. A cells' sensitivity to triggering PCD is impacted by previous stress experience, age and prevailing environmental conditions.