Genetic structure and diversity in Avena sterilis and A. fatua populations in Iran

Avena (Poaceae) is a forage and medicinal annual genus with 27 species in the world of which, 9 species occur in Iran. Avena species show some morphological similarities that make difficult species separations for some taxa. The present study considered the genetic variability in A. fatua and A. sterilis populations. Genomic DNA was extracted from dried leaf samples using a CTAB-modified protocol. Ten Inter Simple Sequence Repeat markers (ISSR) were used to study the genetic variability on 23 populations (90 individuals) of these two species. Genetic diversity parameters, genetic distance and gene flow were determined. Genetic variation at different inter- and intra-populational levels was evaluated. The analysis of molecular variance (AMOVA) and the results of structure analyses showed that there is a high genetic diversity within the populations studied. The Mantel test illustrated a significant correlation between genetic and geographic distances. Despite some morphological similarities between populations, a limited gene flow was observed. Based on the results of the Mantel test, it was found that with the increase in the geographical distance, the genetic distance in the populations of the two studied species increased. According to all the analyses and results obtained, the cause of the gene flow between the populations of the two species studied may be mutation or the impact of environmental factors. Based on the present study’s findings on the genetic and molecular diversity of A. fatua and A. sterilis, it can be concluded that the applied methods and the ISSR markers are effective and efficient in distinguishing taxa.