The origin and evolution of B chromosomes could be explained by the specific DNA sequence on them. But the specific sequences known were quite limited. To investigate maize B chromosome sqicific DNA sequeces, maize ge...The origin and evolution of B chromosomes could be explained by the specific DNA sequence on them. But the specific sequences known were quite limited. To investigate maize B chromosome sqicific DNA sequeces, maize genomes with and without B chromosomes were analyzed by AFLP. Only 5 markers were found specific to genomes with B chromosomes among about 2000 AFLP markers. Southern hybridization and sequence analysis revealed that only the sequence of M8-2D was a B chromosome specific sequence. This sequence contained the telomeric repeat unit AGGGTTT conserved in plant chromosome telomeres. In addition, the sequence of M8-2D shared low homology to clones from maize chromosome 4 centromere as well. M8-2D were localized to B chromosome centrorneric and telomeric regions.展开更多
Hashemi, a popular aromatic rice among Iranians, is famous for its fragrance and taste. Such features are major reasons for its higher price compared to non-aromatic varieties available in Iran. Therefore, the knowled...Hashemi, a popular aromatic rice among Iranians, is famous for its fragrance and taste. Such features are major reasons for its higher price compared to non-aromatic varieties available in Iran. Therefore, the knowledge of genetic diversity of this profitable crop is a fundamental ineterst for plant breeders in future breeding programs. In the present research, genetic diversity among 35 genotypes of Hashemi aromatic rice （Oryza sativa L.） from Guilan and Mazandaran provinces of Iran was estimated using simple sequence repeat （SSR） and amplified fragment length polymorphism （AFLP） markers. Out of 21 SSR and 12 EcoRI-Msel AFLP marker combinations, only 16 SSRs and 10AFLPs exhibited polymorphic patterns while others were monomorphic. The 10 AFLP primer combinations produced a total of 142 of bands and 20 were polymorphic （14.08%）. Moreover, 40 out of 47 bands amplified with 16 SSR markers showed polymorphism （85.1%）. The average num- ber of alleles identified by SSR primers was 2.56 alleles per locus with a range of 2 to 4. The average value of polymorphic information content （PIC） was 0.393 and 0.468 for AFLP and SSR markers, respectively. However, the genetic similarity values ranged from 0.26 to 1 for SSRs and 0.21 to 1 forAFLPs. Later, a unweighted pair group method with arithmetic mean （UPGMA） dendrogram was generated and genotypes were clustered into four groups with SSRs at similarity coefficient of 0.55 while AFLPs clustered them into six groups at similarity coefficient of 0.41. Cluster analysis revealed a narrow genetic diversity and low correlation between geographical differentiation and genetic distance within cultivars.展开更多
RAPDs and AFLPs were used to determine the genetic relationships among 23 elite cultivars of confectionary sunflowers (Helianthas annuus) from different districts in China. Both approaches uniquely fingerprint each of...RAPDs and AFLPs were used to determine the genetic relationships among 23 elite cultivars of confectionary sunflowers (Helianthas annuus) from different districts in China. Both approaches uniquely fingerprint each of the accessions. Twenty-six RAPD primers resulted in a total of 192 strong DNA fragments, ranging from 0.26 kb to 1.98 kb, among which 165 (86.12%) were polymorphic. The average number of DNA band produced by each primer was 7.38. A total of 576 AFLP markers were produced with 8 primer combinations, ranging from 100 bp to 500 bp, and 341 polymorphic bands (59.20%) were revealed. The polymorphism rate was 76.00% and the average bands amplified by per primer combination were 72. Effective number of alleles per locus of RAPD marker (1.76) was larger than that of the AFLP marker (1.65). The mean PIC value of AFLP markers (0.38) was lower than that of the RAPD markers (0.41), but AFLP marker had much higher Ai value (38.52) than RAPD marker (6.38). Genetic similarities from RAPD data ranged from 47.84% to 82.06% and the average Nei's coefficient was 0.649 5; the Nei's coefficient of similarity from AFLP data ranged from 54.15% to 83.52%, and the average Nei's coefficient was 0.688 4. However, standard deviation (SD) of RAPDs was 0.13 but the SD of AFLPs was 0.08. In general, the RAPD data gave lower similarity values and higher SD values than those based on the AFLP analysis. The correlation coefficient between the two genetic similarity matrices was 0.51, revealing the estimations of genetic relationship provided by the two marker systems were only moderate. However, cluster analyses of RAPD or AFLP data divided the 23 sunflower genotypes into identical 3 groups.展开更多
基金This research was supported by grant from National Natural Sciences Foundationof China (39970357).
文摘The origin and evolution of B chromosomes could be explained by the specific DNA sequence on them. But the specific sequences known were quite limited. To investigate maize B chromosome sqicific DNA sequeces, maize genomes with and without B chromosomes were analyzed by AFLP. Only 5 markers were found specific to genomes with B chromosomes among about 2000 AFLP markers. Southern hybridization and sequence analysis revealed that only the sequence of M8-2D was a B chromosome specific sequence. This sequence contained the telomeric repeat unit AGGGTTT conserved in plant chromosome telomeres. In addition, the sequence of M8-2D shared low homology to clones from maize chromosome 4 centromere as well. M8-2D were localized to B chromosome centrorneric and telomeric regions.
基金supported by the Purification of Hashemi Native Rice Varieties in North Regions of Iran, ABRII, Rasht (04-04-91126)
文摘Hashemi, a popular aromatic rice among Iranians, is famous for its fragrance and taste. Such features are major reasons for its higher price compared to non-aromatic varieties available in Iran. Therefore, the knowledge of genetic diversity of this profitable crop is a fundamental ineterst for plant breeders in future breeding programs. In the present research, genetic diversity among 35 genotypes of Hashemi aromatic rice （Oryza sativa L.） from Guilan and Mazandaran provinces of Iran was estimated using simple sequence repeat （SSR） and amplified fragment length polymorphism （AFLP） markers. Out of 21 SSR and 12 EcoRI-Msel AFLP marker combinations, only 16 SSRs and 10AFLPs exhibited polymorphic patterns while others were monomorphic. The 10 AFLP primer combinations produced a total of 142 of bands and 20 were polymorphic （14.08%）. Moreover, 40 out of 47 bands amplified with 16 SSR markers showed polymorphism （85.1%）. The average num- ber of alleles identified by SSR primers was 2.56 alleles per locus with a range of 2 to 4. The average value of polymorphic information content （PIC） was 0.393 and 0.468 for AFLP and SSR markers, respectively. However, the genetic similarity values ranged from 0.26 to 1 for SSRs and 0.21 to 1 forAFLPs. Later, a unweighted pair group method with arithmetic mean （UPGMA） dendrogram was generated and genotypes were clustered into four groups with SSRs at similarity coefficient of 0.55 while AFLPs clustered them into six groups at similarity coefficient of 0.41. Cluster analysis revealed a narrow genetic diversity and low correlation between geographical differentiation and genetic distance within cultivars.
文摘RAPDs and AFLPs were used to determine the genetic relationships among 23 elite cultivars of confectionary sunflowers (Helianthas annuus) from different districts in China. Both approaches uniquely fingerprint each of the accessions. Twenty-six RAPD primers resulted in a total of 192 strong DNA fragments, ranging from 0.26 kb to 1.98 kb, among which 165 (86.12%) were polymorphic. The average number of DNA band produced by each primer was 7.38. A total of 576 AFLP markers were produced with 8 primer combinations, ranging from 100 bp to 500 bp, and 341 polymorphic bands (59.20%) were revealed. The polymorphism rate was 76.00% and the average bands amplified by per primer combination were 72. Effective number of alleles per locus of RAPD marker (1.76) was larger than that of the AFLP marker (1.65). The mean PIC value of AFLP markers (0.38) was lower than that of the RAPD markers (0.41), but AFLP marker had much higher Ai value (38.52) than RAPD marker (6.38). Genetic similarities from RAPD data ranged from 47.84% to 82.06% and the average Nei's coefficient was 0.649 5; the Nei's coefficient of similarity from AFLP data ranged from 54.15% to 83.52%, and the average Nei's coefficient was 0.688 4. However, standard deviation (SD) of RAPDs was 0.13 but the SD of AFLPs was 0.08. In general, the RAPD data gave lower similarity values and higher SD values than those based on the AFLP analysis. The correlation coefficient between the two genetic similarity matrices was 0.51, revealing the estimations of genetic relationship provided by the two marker systems were only moderate. However, cluster analyses of RAPD or AFLP data divided the 23 sunflower genotypes into identical 3 groups.
