Research on transglutaminases in plants lags behind that in mammalian systems, aspects still remaining elusive. In this review, we survey the plant TGase literature published after the previous review. Plant TGases, still unclassified, are widespread in "higher" and "lower" plants, in several plant organs and probably different isoforms are differently located in various cell compartments: chloroplasts, mitochondria, cytoplasm, cell walls. They probably exert a mainly structural or conformational role; however, in chloroplasts and mitochondria their roles might be related to the organelles' specific metabolisms. Transgluta-minases appear related to growth (cell cycle, apical growth, seedling growth), differentiation, programmed cell death and stress
