**2. Programmed cell death in plants**

Programmed cell death (PCD) is a genetically controlled physiological innate mechanism, which involves the selective death of individual cells, tissues or entire organs. It is a process different from necrosis as it occurs passively in response to environmental perturbations [9]. Together with the chromatin remodelling machinery, the cell cycle regulation mechanisms, the nuclear envelope and the cytoskeleton, this process is one of the major eukaryotic innovative aspects, which allowed the development of more complex organisms [10].

Molecular evidences have pointed out that the PCD machinery has evolved since very early stages of the evolutive history, and that this evolution has been processed through expansion and innovation of protein recruitment domains, as well as through the derivation of effector domains and horizontal gene transference events [11].

The best‐understood models in PCD are metazoan organisms and in concern to the cell morphology and involved organelles, two main categories are known: apoptosis and autophagy [12–14].

Apoptosis is defined by three main morphological characteristics: nuclear DNA fragmentation, apoptotic bodies' formation and degradation of the apoptotic bodies on the lysosome of a phagocytic cell [12–14].

Autophagy is the main system of degradation and recycling in eukaryotic cells, contributing to the clearing of cellular compounds and cytosolic portions. This process can occur in two forms: through the cytosolic sequestration by the vacuole or through the sequestration of large portions of cytosol by a structure called autophagosome [15–17].

On situations where a cellular set is under a more intense stress, so that the cells are not able to activate the apoptotic PCD pathway, cell death occurs through necrosis, characterized by a protoplasmic swelling due to the loss of the osmoregulation control capability, and consequent water and ions migration to the cell [18].

In plants, PCD is observed under diverse circumstances through the entire life cycle of many species, as well as in response to biotic and abiotic stimuli, what allows wide biochemical and developmental plasticity [19], as, for example:

