Cytotaxonomic investigation and meiotic behavior of natural populations of genus Avena in Algeria

Karyotype and meiotic analysis were performed on forty-five natural populations of genus Avena sampled in contrasting bioclimatic areas of Northern Africa. The diploids (2n = 2x = 14) A. clauda, A. eriantha and A. hirtula are sporadic in hills and mountains of the Tellian Atlas only. A. wiestii (2x) are scattered in arid and semi-arid regions, of which an unexpected 4x population has been discovered. A. barbata (4x) and A. sterilis (6x) are widespread in all bioclimates while A. fatua (6x) is rather rare. Most populations show remarkable novelties in the intra and inter karyotype asymmetry indexes, particularly the 4x cytotype of the endemic A. macrostachya which has almost exclusively metacentric chromosomes. Both 2x, 4x and 6x annual species display regular meiosis with generally bivalent association. Univalents, multivalents, laggards, bridges, asynchronous divisions and micronuclei were often observed. Meiotic behavior observed for the first time in the locus classicus of A. macrostachya, indicate constant occurrence of one or two tetravalents. Meiotic features together with the main bioclimatic parameters, were submitted to a principal component analysis. Significant correlations were found particularly between frequencies of multivalents and laggards with the Mediterranean bioclimatic coefficient and the maximum temperature of the hottest month. These new cytogenetic data have been discussed in the context of the geographical distribution of diploids and polyploids and the aftermath of the local environmental stress conditions on the meiotic process within natural populations.