Relationships and genetic structure of North African barley (Hordeum vulgare L.) germplasm revealed by morphological and molecular markers: Biogeographical considerations

Abstract

Landraces represent a crucial reservoir of gene pool for crop improvement and a valuable germplasm for sustainable agriculture towards climate change. To establish conservation strategies for barley germplasm, 31 North African landraces were characterized by associating morphogenetic data with molecular markers. Partial relationships were found between divergence pattern and geographic origin at morphological level, while molecular dendrogram clearly separated barley landraces into two major groups based on geographic distribution. Grain yield, glum awn and lemma awn barb appear to be the most discriminative agro-morphological traits required for exploitation of these valuable resources. A total of 114 amplification products were scored by RAPD primers exhibiting an overall 84.85% polymorphism. Molecular variance demonstrated that genetic variation was partitioned within (60.31%) rather than between (39.69%) the populations. Data showed considerable gene flow (Nm=1.439) and moderate genetic differentiation (GST=0.257) with highest diversity observed in Tunisian and Egyptian populations. No significant correlation was found between the distance matrices based on molecular and morphological data indicating no influence of genetic background on the observed morphological variation. These results reinforce the integration of both morphogenetic and RAPD markers as a starting point for in situ conservation of these accessions allowing adaptation to local environments.