Root cortical senescence: An adaptive mechanism for drought tolerance in crops

Senescence allows plants to remove unnecessary tissues and recycle nutrients. Substantial work has focused on the senescence of aboveground tissues such as leaves; by contrast, the senescence of underground tissues has important functions in response to stresses such as drought. The root cortex transports water and provides structure to the root. Root cortical senescence (RCS) involves the programmed cell death of root cortical cells and allows the plant to adjust root system architecture and decrease the metabolic burden of maintaining root tissue. In this review, we synthesize current knowledge on RCS and its responses to drought stress. This review also examines the regulation of RCS at multiple levels and the differences in RCS between monocots and dicots. We further identify major challenges in characterizing RCS, understanding its mechanisms, and applying it in breeding, with an emphasis on bridging laboratory findings and field performance through genotype-by-environment analyses. Finally, we explore potential research directions and breeding targets for translating RCS into improved drought tolerance and yield stability in crops. This helps to clarify the physiological mechanisms of RCS, root system and leaf senescence, enhances the understanding of root system functions, and has significant theoretical value and practical significance for the prevention and control of crop premature senescence as well as the selection of anti-senescence varieties.