Genetic Variability of Different Jordanian Almond Prunus Amygdalus L. Landraces Revealed by Morphological Traits and RAPD Markers

Abstract

The relationship among six Jordanian almond landraces was studied using morphological traits and RAPD analyses. Across six almond landraces studied, nut shape, kernel size, nut length, nut size, and shell length That showed a high level of variation (CV>30%), while kernel length, shell width, internodes length, and nut width showed comparatively low values (CV<20%). Principal component analysis showed that the first five components explained all morphological variation among the landraces investigated. Kernel and nut traits were predominant in the first three components contributing to most of the total variation that existed among landraces. Euclidean distance was used to construct clusters from morphological data which allocated individuals into two main groups with a distance ranging from 5.5 to 10.14. Hajari, Hami Hallo, and Mukhmaly with small fruit sizes composed one main cluster, while the other three landraces (Oga, Fark, and Abu Dabos) with large fruit sizes composed the other main cluster. Out of 62 pre-screened RAPD primers, 12 with reproducible bands and maximum polymorphism were selected for diversity analysis. Seventy-one bands were scored with 28 of them being the polymorphic. Average value of polymorphism/primer ranged from 20% to 74.2%. Nei's genetic distance coefficient ranged from 0.5 to 0.85 with an average of 0.70. Molecular analysis revealed inconsistent separation among the landraces compared with that based on morphological traits. Although landraces found during the screening in the Ajloun area are limited in number, but considerable variation was observed both at morphological and DNA levels indicating that Jordanian almond landraces are rich and valuable genetic materials for almond improvement.