The endosymbiosis that leads to organelle formation follows distinct key processes and stages: recognition between symbionts, engulfment, the failure of defense systems to eliminate the endosymbiont by defense reaction, physiological integration and finally, genetic integration ( Margulis and Chapman, 1998). Mitochondria and chloroplasts of eukaryotic cells, key organelles for respiration and photosynthesis, are thought to result from the evolution of an ancient endosymbiosis in which ancient bacterial-like organisms were engulfed into an ancient prokaryotic or eukaryotic-like cell ( Dyall et al., 2004 Kutschera and Niklas, 2005 Zimorski et al., 2014 Archibald, 2015). Endosymbiotic theories to explain the origin of eukaryote cells and their organelles have been proposed and discussed for more than a century ( Zimorski et al., 2014 Martin et al., 2015 O'Malley, 2015). Endosymbiosis is a reciprocal advantageous association in which one organism lives inside another and it has a pivotal importance in symbiogenesis. Symbiosis between different organisms has played a key role in evolution and in fact, the term “symbiogenesis” is an evolutionary concept that refers to “the appearance of new physiologies, tissues, organs, and even new species as a direct consequence of symbiosis” ( Chapman and Margulis, 1998 Margulis and Chapman, 1998 O'Malley, 2015). Thus, our current understanding of the symbiosome suggests that it might be considered a nitrogen-fixing link in organelle evolution and that the distinct types of legume symbiosomes could represent different evolutionary stages toward the generation of a nitrogen-fixing organelle. ![]() Different degrees of symbiosome evolution can be defined, specifically in relation to rhizobial infection and to the different types of nodule. As a result, it can be concluded that the symbiosome possesses organelle-like characteristics due to its metabolic behavior, the composite origin and differentiation of its membrane, the retargeting of host cell proteins, the control of microsymbiont proliferation and differentiation by the host legume, and the cytoskeletal dynamics and symbiosome segregation during the division of rhizobia-infected cells. ![]() Here, we review what is currently known about legume symbiosomes from an evolutionary and developmental perspective, and in the context of the different interactions between diazotroph bacteria and eukaryotes. In most legumes, the rhizobia infect post-mitotic cells that have lost their ability to divide, although in some nodules cells do maintain their mitotic capacity after infection. ![]() In legume nodules, symbiosomes containing endosymbiotic rhizobial bacteria act as temporary plant organelles that are responsible for nitrogen fixation, these bacteria develop mutual metabolic dependence with the host legume. Timiryazev Institute of Plant Physiology, Russian Academy of Science, Moscow, Russia 2Centro de Estudios Avanzados en Zonas Áridas (CEAZA), La Serena, Chile.1Instituto de Ciencias Agrarias ICA-CSIC, Madrid, Spain.Teodoro Coba de la Peña 1,2 Elena Fedorova 1,3 José J.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |