Inside of these nodules, the rhizobia differentiate into bacteroids and convert N 2 gas into ammonium ( Oldroyd and Downie, 2008 Kuever et al., 2015 Ormeño-Orrillo et al., 2015 Peix et al., 2015 Mus et al., 2016). Rhizobia are soil-borne bacteria that colonize plant tissues inter- or intra-cellularly and trigger the development of new organs called nodules, which generally happens on legume roots. These observations suggested that complex rearrangement, such as horizontal transfer and insertion of different DNA elements, might be responsible for the plasticity of the Bradyrhizobium genome. Lb8 possessed both Type III and Type IV protein secretion systems, and our work elucidated the association of flagellar Type III secretion systems in bradyrhizobia. Of 21 genes annotated as transposase, 16 were located in the symbiosis island. A total of 711 putative protein-encoding genes were in this region, among which 455 genes have potential functions related to symbiotic nitrogen fixation and DNA transmission. A presumptive symbiosis island of 778 Kb was detected, which included two clusters of nif and nod genes. The genome shared 92% of the gene families with B. Fifty-eight percent of the predicted genes showed similarity to genes of known functions and were classified into 27 subsystems representing various biological processes.
A total of 8,433 potential protein-encoding genes, one rRNA cluster, and 51 tRNA genes were annotated. No plasmid sequence was detected in the sequenced DNA sample.
The complete genome sequence was a circular chromosome of 8,718,147 base-pair (bp) with an average GC content of 63.14%. strain, Lb8 from peanut root nodules and sequenced it using PacBio long reads. In this study, we isolated a Bradyrhizobium sp. To understand the intercellular crack entry process, it is critical to develop the tools and resources related to the rhizobium in addition to focus on investigating the mechanisms of the plant host.
However, the nodulation of peanuts ( Arachis hypogaea L.) by Bradyrhizobium strains requires an intercellular colonization process called “crack entry,” which is understudied. In many legumes, the colonization of roots by rhizobia is via “root hair entry” and its molecular mechanisms have been extensively studied. 5Plant Molecular and Cellular Biology Program, Genetic Institute, University of Florida, Gainesville, FL, United States.
4Departments of Bacteriology and Agronomy, University of Wisconsin–Madison, Madison, WI, United States.3Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL, United States.2Department of Microbiology, Weber State University, Ogden, UT, United States.1Agronomy Department, University of Florida, Gainesville, FL, United States.Dev Paudel 1, Fengxia Liu 1, Liping Wang 1, Matthew Crook 2, Stephanie Maya 1, Ze Peng 1, Karen Kelley 3, Jean-Michel Ané 4 and Jianping Wang 1,5 *