[Super-species genetic systems].

Abstract

Genetic integration of diverse organisms results in generation of three types of the super-species systems of heredity: metagenome (set of genetic factors of the microbial community which occupies a certain ecological niche), symbiogenome (functionally integrated system of the partners' symbiotic genes) and hologenome (entire hereditary system of a symbiotically originated organism). The integrity of metagenome is based on the cross-regulation and horizontal transfer of genes in co-evolving organisms which in the soil microbial communities are accompanied by maintenance of the stable extracellular DNA pool. Formation of symbiogenome is related to the highly specific partners' signaling interactions which are responsible for development of the joint metabolic pathways based on the specialized cellular and tissue structures. Transitions of symbiogenome into hologenome are due to the endosymbiotic gene transfer from microsymbionts to their hosts. In symbiotic bacteria, these transitions are coupled with establishments of multi-component, reduced and rudimentary genomes revealed for the ecologically obligatory symbionts, genetically obligatory symbionts, and cellular organelles, respectively. Their evolution is related to the stringency of transmission of microsymbionts by hosts increased from pseudo-vertical (via environment) to the trans-embryonic (via embryos and the surrounding tissues) and trans-ovarian transmission (via germ cells) which are culminated in the cytoplasmic inheritance of cellular organelles. We suggest the hypothesis about generation of endophytic plant symbiogenome on the basis of soil metagenome subjected to the control of host by its involvement into the quorum sensing auto-regulation of microbial community.