Saving for a rainy day: Control of energy needs in resurrection plants.

Plants constantly respond to threats in their environment by balancing their energy needs with growth, defence and survival. Some plants such as the small group of resilient angiosperms, the resurrection plants, do this better than most. Resurrection plants possess the capacity to tolerate desiccation in vegetative tissue and upon watering, regain full metabolic capacity within 72 h. Knowledge of how these plants survive such extremes has advanced in the last few decades, but the molecular mechanics remain elusive. Energy and water metabolism, cell cycle control, growth, senescence and cell death all play key roles in resurrection plant stress tolerance. Some resurrection plants suppress growth to improve energy efficiency and survival while sensitive species exhaust energy resources rapidly, have a diminished capacity to respond and die. How do the stress and energy metabolism responses employed by resurrection plants differ to those used by sensitive plants? In this perspective, we summarise recent findings defining the relationships between energy metabolism, stress tolerance and programmed cell death and speculate important roles for this regulation in resurrection plants. If we want to harness the strategies of resurrection plants for crop improvement, first we must understand the processes that underpin energy metabolism during growth and stress.