Plants respond rapidly to defend themselves from multiple environmental insults that include biotic and abiotic challenges. One common manifestation of plant defense is programmed cell death (PCD). For example, when the leaves of a plant age they can die and fall off, but before doing so they 'senesce' and return their nutrients to the plant. This occurs in trees in the autumn before leaf fall. In certain types of abiotic stress, for example drought or osmotic stress, the onset of cell death can be sudden yet in some ways programmed and reversible.
PCD is also important in plant-fungal biotrophic-type interactions where the plant host tissue is maintained by the pathogen in a ‘zombie-like’ state in service of the pathogen. In a resistance response, the infected parts of the plant can elect to undergo a local process of PCD or hypersensitive response, trapping the disease locally. In both biotic and abiotic responses host death proteases released from the vacuole and host production of reactive oxygen species (ROS) play and important role in initiating and controlling PCD. We wish to understand these molecular aspects of plant-stress reaction by defining the spatial and temporal context of plant stress.