RAPD, karyology and selected morphological variation in a model grass, Brachypodium distachyon

Jaroszewicz AM, Kosina R & Stankiewicz PR (2012). RAPD, karyology and selected morphological variation in a model grass, Brachypodium distachyon. Weed Research52, 204216. Summary Recognition of variation patterns at the level of DNA, chromosomes and plant morphology, and their interrelationships were the object of this research on Brachypodium distachyon. RAPD profiles, cytogenetics of root mitoses, gross morphology and microstructures were studied in B.similar to distachyon for 18 accessions, as well as for three selections with a narrowed gene pool, all from the Mediterranean and Irano-Turanian region. For the scored RAPD bands, 309 were polymorphic (96%). The average expected gene diversity (Hi) for all primers was 0.220, which is close to the variation noted in the Asian-European region of origin. In the UPGMA dendrogram, accessions were not clustered according to their geographic origin. High variability in cytogenetics was found. Levels of chromosome ploidy differentiated accessions. A cytogenetic mosaic was expressed in the form of aneuploidy and anomalous mitoses. Accessions presenting similar cytogenetic variability were not clustered in the RAPD dendrogram. The period of vegetative growth varied greatly. Zoochoric characteristics of diaspores and endosperm volume showed interaccessional variability. No distinct linkage between RAPD patterns and morphology was found. High variation in all studied characteristics of the plant was noted, which is a good base for natural selection of intraspecific units (inbred lines). The narrowing of the gene pool is an effective tool of microevolution and facilitates the distribution of the species according to the founder principle. The comparison of this evolutionary potential of B.similar to istachyon with patterns of evolution of other annual weedy grasses would be of great value for weed science.