Do green plants age, and if so, how?

Abstract

Time-dependent ageing-like processes in green plants are discussed and compared to gerontological changes in animals and other organisms. The question of plant ageing is inseparable from the issue of the developmental architecture of plants. Modular structure and fractal, recursive patterns of plant development mean that the concept of an individual, and hence of whole-organism ageing, is ambiguous. Selective disposal of cells, tissues and organs, a major determinant of perenniality and hence lifespan, is a morphogenetic and adaptive tool that superficially resembles, but is fundamentally different from, ageing. The contrast between autotrophs and heterotrophs in the relation between resource acquisition and allocation is discussed, particularly partitioning between reproductive and vegetative development. Genetic, environmental, and epigenetic factors influencing ageing-like behaviour, including senescence, stress responses, somatic mutation and phase change, are considered. Finally, mechanisms are proposed for the origin of ageing as an intrinsic property of living cells.