Genetic similarities among Iranian populations of Festuca, Lolium, Bromus and Agropyron using amplified fragments length polymorphism [AFLP] markers

The study of genetic variation and phylogenetic relationships is essential for the efficient selection of superior plant material and conducting introgression breeding programs. In Iran, despite the wide geographical distribution of grasses no report is available on the genetic diversity and relationships of cool season grass populations. In this study amplified fragment length polymorphism [AFLP] was used to study 42 populations from eight species of Festuca arundinacea Schereb., Festuca. pratensis Huds., Festuca. rubra L., Festuca. ovina L., Lolium perenne L., L. rigidum Gaud., Bromus tomentellus Boiss. and Agropyron cristatum [L] Gaertn. The number of amplified products ranged from 11 to 78 per primer combination and a total of 497 markers were scored. Jaccard's genetic similarity coefficients among populations ranged from 0.15 to 0.88 showing high levels of inter and intra-specific genetic diversity. The cluster analysis and principle coordinate analysis [PCOA] reflected the phylogenetic relationships among species and clearly demonstrated differences in the degree of similarity among accessions. Results indicated that AFLP is a useful technique to reveal genetic diversity at different taxonomic levels of grasses and might facilitate the selective introgression of useful genes in plant breeding programs

Karyotype and nuclear DNA content of hexa-, octo-, and duodecaploid lines of Bromus subgen. Ceratochloa

The subgenus Ceratochloa of the genus Bromus includes a number of closely related allopolyploid forms or species that present a difficult taxonomic problem. The present work combines data concerning chromosome length, heterochromatin distribution and nuclear genome size of different 6x, 8x and 12x accessions in this subgenus. Special attention is paid to the karyotype structure and genomic constitution of duodecaploid plants recently found in South America. Hexaploid lineages possess six almost indistinguishable genomes and a nuclear DNA content between 12.72 pg and 15.10 pg (mean 1Cx value = 2.32 pg), whereas octoploid lineages contain the same six genomes (AABBCC) plus two that are characterized by longer chromosomes and a greater DNA content (1Cx = 4.47 pg). Two duodecaploid accessions found in South America resemble each other and apparently differ from the North American duodecaploid B. arizonicus as regards chromosome size and nuclear DNA content (40.00 and 40.50 pg vs. 27.59 pg). These observations suggest that the South American duodecaploids represent a separate evolutionary lineage of the B. subgenus Ceratochloa, unrecognized heretofore.