stributed across all linkage groups with no significant bias towards any specific chromosome although a slightly larger number of BES SSR loci were found on linkage groups b02d and b08f. The good coverage of the BMb markers is in contrast to other SSR mapping studies in common beans especially for the n based BM markers, the gene based BMd markers Purmorphamine the AT rich BMa markers Purmorphamine and to some extent other PV markers, all of which have tended to be more clustered. One of the goals of including new microsatellites in a previously constructed genetic map was to fill in map coverage especially in gaps from this previous mapping, As a result, we wanted mole cular markers that did not map together but rather mapped uniformly across the genome.
The complemen tarities of the BES SSR markers with previous mapping allowed us to supplement coverage on nearly all the linkage groups, but especially on b01h, b03c, b05e, b06g, b08f and b10j. As a result, the average number of microsatellites per linkage group in the DOR364 × G19833 map stands at 19. 5 with all linkage groups having more Purmorphamine than 15 SSR loci except for B06g. For some unknown Messenger RNA Purmorphamine reason linkage group b02d was heavily populated by microsatellites in this study as well as pre viously, The uniformity of the BES SSR loci across the genome may be related to the fact that the BAC ends were a representative sample of the entire genome and to the similar and uniform physical size of common bean chro mosomes, based on cytogenetic study by Pedrosa Har and, In that study, the authors assigned linkage groups to common bean chromosomes based on pre viously mapped single copy RFLP sequences used as FISH probes.
The authors determined chromosome size based on FISH signal strength assuming a genome size of 637 Mb, and found that b01h, b03c, b07a and b08f all had similar sizes between 64 and 67 Mb, while b06g Purmorphamine had a smaller size and the rest were intermedi ate with sizes between 52 and 59 Mb. Tight correlation was not found between the physical length for each chromosome and the number of BES SSR markers mapped for each linkage group in our study or the genetic length of the linkage group, meaning that the largest chromosomes did not have more SSRs or longer length as a genetic map.
However, we have observed in the past that microsatellites from enriched libraries that target only a few motifs such as long GA CT, CA GT or ATA TAT repeats were biased towards cer tain chromosomes such as b02d and b04b and towards specific chromosomal regions, The uniform distribution of the BES SSR Purmorphamine markers would be the result of different factors. For example, the fact that we targeted Purmorphamine various SSR motifs may have helped increase the chances of having randomly distrib uted markers, In addition, the restriction enzyme used to generate the BAC library in the physical map ping project may have helped ensure an even genomic distribution. In our case, the BAC clones and resulting BES were from a HindIII derived BAC library for the Andean genotype G19833, Notably, HindIII is a type II site specific enzyme with a fairly common restriction site therefore it is likely that distribution of the enzyme digestion sites may have contributed to eliminating biases in the BAC contigs generated.
Like wise, the BES we sampled were from the entire library and therefore the eventual map location of BES SSRs was random. These results also suggest, as previously postulated Purmorphamine by Pedrosa Harand et al, that repeats can be interspersed with single copy sequences in regions different from pericentromeric heterochromatin. Despite the random distribution, segregation distor tion toward a specific genotype and assignment of dis torted markers in a few clusters was observed. Segregation distortion is quite often observed in com mon bean as described by Blair et al, Checa and Blair and Frei et al. and suggests the existence of incompatibility genes, or genes for sporophytic selec tion and gamete elimination in the species. In this study segregation distortion was ob
Wednesday, April 23, 2014
Five various Successful Tricks Of IU1AZ20 Which Rarely ever Fails
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