An Investigation of Genetic Diversity among Some Almond Genotypes and Species by Morphological Traits
Almond [Prunus dulcis (Mill.) D.A. Webb] is one of the species of genus Prunus and subgenus Amygdalus (Rosaceae, subfamily Prunoideae). It is grown commercially worldwide. Iran is one of the main growing areas for commercial and wild almonds due to its suitable climatic conditions. Wild almond species are known to be tolerant to harsh environmental conditions such as drought. They also can be used as rootstock or can be employed in improvement programs. In this study, 62 genotypes including eight different species were evaluated by measuring 15 morphological traits. Correlation coefficient showed significant correlation among length of trunk, diameter of trunk, tree vigor, foliage density, length of main branches, thickness of one year old shoot, leaf length and width, leaf area and the leaf length/width ratio. Principal component analysis showed that length of main branches, ramification, length of one year old shoot, leaf length and width, leaf area and the length/width ratio of leaf had highest loading in the first component that accounted for 35.6% of total variation (67.8%). Cluster analysis divided genotypes into two main groups and wild species were separated at distance of 5 from the others.
Genetic Diversity and Relationships among Some Iranian Cultivated Almond Genotypes and Related Wild Species Using RAPD Markers
Iran is worldwide one of the main growing regions for commercial and wild almonds due to its suitable climatic conditions. In this study, we characterized using RAPDs the genetic diversity and relationships between 62 almond genotypes, including eight related species (P. dulcis, P. scoparia, P. arabica, P. eburnea, P. erioclada, P. lycioides, P. orientalis and P. communis). Sixteen RAPD primers (TIBMOLBIOL Co., Germany) produced 260 bands from which 250 were polymorphic (96.15%). Total resolving power (Rp) was 121.83, ranging from a minimum of 4.25 for TIBMBB-16 to a maximum of 11.64 for TIBMBD-05. Jaccard similarity coefficient was calculated and was used to construct an UPGMA dendro-gram. Similarity values among the studied genotypes ranged between 0.28 and 0.79 with an average of 0.53. Cluster analysis and principle coordinate analysis (PCoA), partially discriminated the genotypes studied regarding their geographical origin. At the similarity of 0.52 in the dendrogram, the genotypes were divided into four sub-clusters. Our results indicated a wide genetic diversity at molecular level for the existing almond germplasm in Iran.