Cytogenetic Investigation of Setaria vertrcillata L. and Eragrostis aegyptiaca Willd. from Egypt

抄録

Two species of Setaria verticillata and Eragrostis aegyptica from Egypt were carried out under cytogenetic investigation in this study. They are very common and widely spreed grass belong family poaceae, mostly distributed in Nile delta region.
All accessions collected for each species show no significance variation in morphological measurements. Mitotic chromosome investigation shows that Setaria verticillata has 18 chromosomes (x = 9) as diploid species, where Eragrostis aegyptiaca has 40 chromosomes based on x =10 as tetroploid species. Karyotype structure of the two species shows degree of dissimilarity of the first species within chromosome set in the length and centromere position (show types of metacentric, submetacentric and telocentric). Chromosome set also shows satellite chromosome with probability of translocation in one pair of chromosomes. In contrast the second species shows a karyotype structure with high degree of homogeneity in length and centromere position (mostly metacentric).
Parameters of meiotic division as chromosome association, chiasmata frequency and pollen fertility as well as seed set were investigated for the two species. Meiosis of Setaria verticillata recorded low chiasmata frequency, low pollen fertility low percentage of seed set and more frequent aberrated cells. This in contrast to Eragrostis aegyptiaca, where meiosis show, normal behaviour of chromosomes, low aberration, high fertility and seed set.
The mitotic and meiotic results observe the cytogenetic situation of the two species. The results pointed to the genetic instability of Setaria verticillata and the probability of hybriditynature of the species through out breeding with near by another diploid species. On other hand the results insure the genetic stability of Eragrostis aegyptiaca and confirm its autotetraploid nature.