Cytological relationships of selected species of Panicum.
1994
Hamoud M.A. | Haroun S.A. | Macleod R.D. | Richards A.J.
The cytological investigation of 12 taxa of Panicum revealed that the vast majority of them have basic number x=9 at different ploidy levels. The basic number x=8 was recorded only in the tetraploid species P. maximum with 2n=32. The diploid number 2n=18 was encountered in P. capillare, P. laevifolium, P. antidotale and P. coloratum (2) with 3B-chromosomes recorded in the latter species. The tetraploid chromosome number 2n=36 was found to exist in P. miliaceum., P. miliare, P. coloratum (1) and P. virgatum. The hexaploid number 2n=54 was recorded in P. bulbosum, P. dichotomiflorum and P. esculentum. The karyotypes of all accessions were mostly symmetrical and mainly comprised of meta- and submetacentric chromosomes with little variation in length among them within each karyotype. Investigation of chromosome association during metaphase I of meiosis revealed that the frequency of bivalents/cell was the highest among all investigated diploid, tetraploid and hexaploid accessions. Univalents were also frequently encountered in various accessions. These results may indicate that segmental alloploidy has been the major process by which polyploid species have originated.
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