Brazilian-adapted soybean Bradyrhizobium strains uncover IS elements with potential impact on biological nitrogen fixation

ABSTRACTBradyrhizobium diazoefficiens CPAC 7 and Bradyrhizobium japonicum CPAC 15 are broadly used in commercial inoculants in Brazil, contributing to most of the nitrogen required by the soybean crop. These strains differ in their symbiotic properties: CPAC 7 is more efficient in fixing nitrogen, whereas CPAC 15 is more competitive. Comparative genomics revealed many transposases close to genes associated with symbiosis in the symbiotic island of these strains. Given the importance that insertion sequences (IS) elements have to bacterial genomes, we focused on identifying the local impact of these elements in the genomes of these and other related Bradyrhizobium strains to further understand their phenotypic differences. Analyses were performed using bioinformatics approaches. We found IS elements disrupting and inserted at regulatory regions of genes involved in symbiosis. Further comparative analyses with 21 Bradyrhizobium genomes revealed insertional polymorphism with distinguishing patterns between B. diazoefficiens and B. japonicum lineages. Finally, 13 of these potentially impacted genes are differentially expressed under symbiotic conditions in B. diazoefficiens USDA 110. Thus, IS elements are associated with the diversity of Bradyrhizobium, possibly by providing mechanisms for natural variation of symbiotic effectiveness.

IRAP variability in Prunus domestica (L.) borkh based on Cassandra retrotransposon polymorphism

Plum species are reported to possess a wide genomic variability and that is why DNA markers are still actual in the characterization of its germlasm. In this study, twenty-three genotypes of European plums were assessed for the amplified length based polymorphism among the retrotransposon Cassandra insertions in their genomes. The obtained insertional polymorphism caused by the activity of Cassandra showed regional and pedigree differences in the analysed accessions of European plums. Two primers were used in analysis. The first resulted in the amplification in 203 amplicons and the 86.6 % polymorphism. Two unique fragments were obtained for the Torysa and Podol?nec varieties using this primer. The second primer resulted in the amplification in 267 amplicons and 74.2 % polymorphism. Four unique fragments were obtained for the plum varieties Svestka dom?c?, Cacansk? rann? and Elena. Hierarchical cluster analysis divided the analysed accessions into the four main clusters. To show the length polymorphism diferences of the analysed genotypes from Germany, Slovakia and former Yugoslavia more pecisely, the scattergram for them was constructed.

IRAP and REMAP-based assessment of genetic diversity in chickpea collection from Iran

Retrotransposons (RTN) make a significant contribution to the size, organization and genetic diversity of their host genomes. Several RTN families have been identified in chickpea (Cicer arietinum L.) and other closely related species. In the current research, integration activity and insertional polymorphism of the RTNs CARE1, Tms1Ret1, TPS and LORE were studied in 64 chickpea accessions collected in Iran using inter retrotransposon amplified polymorphism (IRAP) and retrotransposon-microsatellite amplified polymorphism (REMAP) techniques. Results indicated that all RTNs studied, are transpositionally active in chickpea genome and amplified scorable and polymorphic banding pattern. Among the RTN families used, the highest percentage of polymorphic loci (PPL) was produced by TPS family (81.82%). Totally, 129 loci were amplified using 18 IRAP and REMAP primers which 83 (64.34%) were polymorphic. The Dice genetic similarity coefficients among accessions ranged from 0.84 (accessions Tj48 and Ba4) to 0.98 (accessions Ka30 and Urm61), averaging 0.93. The parameters of expected heterozygosity (He), Shannon?s information index (I) and number of effective alleles (Ne) were the highest for Urmia accessions. Cluster analysis based on UPGMA algorithm and Dice similarity coefficient categorized the 64 accessions in 7 main groups. The mean Fst values of all groups except for groups IV and VII, were lower than 0.20, demonstrating no clear differentiation among the groups, no genetic structure of the studied chickpea collection and probably occurrences of gene flow among the origins. In conclusion, although RTN-based markers were able to differentiate the chickpea accessions but the measured relative genetic similarity among accessions were not correlated with geographical distances between places of their origins.

Infectious Endogenous Retroviruses in Cats and Emergence of Recombinant Viruses

Endogenous retroviruses (ERVs) comprise a significant percentage of the mammalian genome, and it is poorly understood whether they will remain as inactive genomes or emerge as infectious retroviruses. Although several types of ERVs are present in domestic cats, infectious ERVs have not been demonstrated. Here, we report a previously uncharacterized class of endogenous gammaretroviruses, termed ERV-DCs, that is present and hereditary in the domestic cat genome. We have characterized a subset of ERV-DC proviral clones, which are numbered according to their genomic insertions. One of these, ERV-DC10, located in the q12-q21 region on chromosome C1, is an infectious gammaretrovirus capable of infecting a broad range of cells, including human. Our studies indicate that ERV-DC10 entered the genome of domestic cats in the recent past and appeared to translocate to or reintegrate at a distinct locus as infectious ERV-DC18. Insertional polymorphism analysis revealed that 92 of 244 domestic cats had ERV-DC10 on a homozygous or heterozygous locus. ERV-DC-like sequences were found in primate and rodent genomes, suggesting that these ERVs, and recombinant viruses such as RD-114 and BaEV, originated from an ancestor of ERV-DC. We also found that a novel recombinant virus, feline leukemia virus subgroup D (FeLV-D), was generated by ERV-DCenvtransduction into feline leukemia virus in domestic cats. Our results indicate that ERV-DCs behave as donors and/or acceptors in the generation of infectious, recombinant viruses. The presence of such infectious endogenous retroviruses, which could be harmful or beneficial to the host, may affect veterinary medicine and public health.