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
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.
