leguminosarum and R. etli [10, 37]. Figure 3

Distribution of replicon specific genes in the tested Rlt nodule isolates. Southern hybridization assays were carried out with several chromosome and plasmid markers of RtTA1 as molecular probes. The position of a given markers in RtTA1 BTK inhibitor genome was shown in the left column. Positive hybridization was colored regarding its location in one of the following genome compartments of Rlt isolates: chromosome (red), chromid-like (violet), plasmids (blue) and pSym (green); (-) indicates that given marker was not detected within a genome under applied Southern hybridization conditions. The letters a-f below the strains name indicate respective plasmids, ch-chromosome. Southern hybridizations with probes comprising markers previously identified on different RtTA1 replicons [36], such as prc and hlyD of pRleTA1d; lpsB2, orf16-orf17-otsB, tauA and orf14 genes cluster of pRleTA1c; nadA and pssM (surface polysaccharide synthesis region Pss-III) of pRleTA1b, DMXAA were carried out. These analyses demonstrated that pRleTA1d markers were almost always jointly detected in the largest chromid-like replicons (only in K3.22 and K5.4 they are separated between distinct chromid-like replicons). pRleTA1c markers in almost all (21 out of 23) of the sampled strains

were located in the genome compartment designated as ‘other plasmids’ (Figure 3). From among markers of pRleTA1b, nadA, minD, hutI and pcaG had always chromid-like location, while the pssM

gene was located in the chromosome of 19 strains, in chromid-like replicons of four strains including RtTA1, and was absent in the genome of K3.22 strain, respectively (Figure 3). Besides the symbiotic genes nodA and nifNE used for identification PJ34 HCl of pSym plasmids, stability of thiC and acdS (Table 1) of the pRleTA1a symbiotic plasmid (ipso facto described as markers of the ‘other plasmids’ pool) was examined (Figure 3). Only thiC was identified in all the strains, however, located in different genomic compartments: most frequently on the chromosome (18 of 23 strains), and in the ‘other plasmids’ (5 strains). The acdS gene was detected in 14 of 23 strains, in each case on pSym (Figure 3). The thiC gene, similarly to fixGHI, showed high variability in location; however, its putative mobile element location is unknown [38]. thiC was reported as plasmid located in sequenced genomes of Rlv [6], Rlt2304 [33] and Rhe [5]. As a IWP-2 nmr result, genes with a stable location in specific genome compartments in all the strains, as well as unstable genes with variable, strain-dependent distribution were distinguished (Figure 4). Stable markers for each compartment of the sampled strains were established i.e. chromosomal: rpoH2, exoR, dnaK, dnaC, bioA, rrn, lpxQ, pssL and stbB; chromid-like: prc, hlyD, nadA, minD, hutI and pcaG; ‘other plasmids’: otsB, lpsB2 (exceptionally chromid-like in K3.6), tauA and orf14 (exceptionally chromid-like in K3.