Programmed cell death (PCD) systems have been extensively studied for their significant role in a variety of biological processes in eukaryotic organisms. Recently, more and more researches have revealed the existence of similar systems employed by bacteria in response to various environmental stresses. This paper summarized the recent researching advancements in toxin/antitoxin systems located on plasmids or chromosomes and their regulatory roles in bacterial PCD. The most studied yet disputedmazEFsystem was discussed in depth, and possible roles and status of such a special bacterial death and TA systems were also reviewed from the ecological and evolutionary perspectives.

Pantoea agglomerans is characterized by the formation of multicellular symplasmata. One unanswered question regarding this bacterium is how these str