Chromosomal diversity and morphological dimorphism in Moroccan wild oat, Avena agadiriana

Chromosomal diversity and morphological dimorphism were examined by breeding the intraspecific hybrids among six accessions of Avena agadiriana Baum et Fedak. The accession M55 occasionally showed a quadrivalent, which indicated that it was heterogeneous for a reciprocal translocation. The chromosome pairings in the intra-early-flowering ecotype hybrids were almost normal with high chiasma frequency at metaphase I. However, the intra-late-flowering ecotype hybrids showed a quadrivalent or a trivalent with a univalent, similar to the inter-ecotype hybrids. The marginal population of the northeastern end, M74, always showed a quadrivalent or a trivalent in all the hybrids due to a unique large reciprocal translocation. This result was consistent with the late-flowering ecotype. There was a genocline of the chiasma frequency resulting from chromosomal rearrangements between adjacent populations. There was also a significant negative correlation between the mean chiasma frequency and the annual rainfall in each collection site (r = ?0.880). The two distinct ecotypes were characterized by the different magnitude and number of chromosomal rearrangements, reciprocal translocation and loss of satellite chromosomes, and they were adapted to the wide range of environments along the Atlantic coast of Morocco.