New faces in plant innate immunity: heterotrimeric G proteins

Co-existence of species seems to inevitably result in origin of parasitism and hence development of molecular mechanisms of attack and defense. Certain similarities between plant and animal defense systems point to an ancient inheritance of the innate immunity. Heterotrimeric G proteins are structurally conserved signaling molecules connecting plasma membrane bound receptors to cytoplasmic effectors. They were found in most eukaryotic organisms. Their role in human pathophysiology and animal diseases was well established. In plants these proteins were also recently implicated in innate immunity. However, molecular mechanisms governed by G proteins and providing resistance against plant pathogens seem to be different from those in animal systems and largely remain elusive. In this review we attempted to sketch current ideas of plant defense system and to present a contemporary status of heterotrimeric G proteins in plant innate immunity.