Morphological and genetic variation in Aegilops geniculata Roth. from Tunisia

Aegilops geniculata Roth is an annual grass relative to cultivated wheats and is widely distributed in North Africa. In order to understand the diversity of this species, 13 populations collected in different bioclimatic areas in north and central Tunisian were analyzed using morphological and molecular characters. Principal component analyses (PCA) based on the agro-morphological characters allowed the separation of populations in five mainly bioclimatic groups characterized by different morphological patterns. Populations originated from humid coastal areas were characterized by good vegetative development, vigorous spikes and caryopses. Samples collected from mean altitude with sub-humid climate had late germination and a large growing cycle a high biomass production and weak caryopses. Populations collected from intermediate and high mountains with sub-humid and semi-arid conditions presented good fertility and high yield-related. Individuals with early germination, weak vegetative development and high caryopses yield characteristics of the coastal areas and plains in sub-humid and the upper semi-arid climate. Populations originated from steppic highlands in upper arid conditions and mean and high altitudes mountains with upper semi-arid were characterized by low morphological development, weak fertility reduction of yield-related and shortening of growing cycle. Individuals were distinguished successively by Phenological, morphological and Yield-related traits. RAPD analysis based on the phenotypic variability and genetic distances revealed a significant variation within and between populations associated with bioclimatic conditions, in particular winter temperature. Genetic diversity was higher in populations growing under warm bioclimates than in those from cold bioclimates.