Manipulation of Programmed Cell Death Pathways Enhances Osmotic Stress Tolerance in Plants: Physiological and Molecular Insights

Programmed cell death (PCD) refers to the death of a cell that is genetically programmed. Alongside cell division and cell migration, PCD enables the organism to strictly control cell numbers and tissue size as well as to protect itself from unwanted cells that threaten homeostasis. Programmed cell death, specifically apoptosis, a physiological form of cell death, was first reported in the nematode C. elegans in 1972. Since this initial discovery, the functional roles of programmed cell death have been intensely scrutinized and observed across kingdoms ranging from animals to plants. Akin to their mammalian counterparts studies have shown that PCD pathways are vital players in the mediation of plant responses to a range of abiotic stresses, including drought. This chapter will provide: (1) an overview of PCD and its roles during development and in response to environmental stimuli; (2) comprehensive literature review of PCD with details of execution and regulation of apoptosis—the most understood form of PCD; (3) PCD and factors that induce cell death in plants; (4) physiological basis of manipulation of PCD pathways enhancing tolerance to abiotic stress in plant; (5) molecular studies of manipulation of PCD pathways as a mechanism of drought stress tolerance in plants and (6) implication and future directions.