Simbiogenetics of microbe-plant interactions

We present the concept of symbiogenetics defined as a branch of general genetics which investigates the Super-Organism Genetic Systems (SOGS) formed due to functional integration of partners' genes during symbiotic interactions. The minimal hereditary unit within SOGS involves no less than a pair of genes that belong to different partners and interact according to the models of complementation or epistasis. Using the examples of plant-microbe interactions we demonstrate that the integrity of SOGS is maintained due to tight signal interactions between partners and is manifested as formation of common biochemical pathways and as development of special symbiotic structures. Using the models of nodule development we demonstrate that the origin of SOGS involves recruiting of genes, which performed diverse functions in free-living organisms, into the symbiotic regulatory networks. The progressive evolution of nodule structures in different dicot lineages was based on the parallel recruiting of genes from the ancestral gene pool into symbiotic regulatory networks. The majority of mutualistic and antagonistic plant-microbe symbioscs represent the components of an evolutionary continuum that originated early in land plants and underwent intensive transformations due to high plasticity of SOGS based on inter- and intra-gene recombination