Genetic Diversity Assessment of Some Citrus Species Cultivated in Iraq Based on RAPD Molecular Marker.

Abstract

Genotyping of six Citrus accessions was carried out using RAPD marker .The genetic variability among the six Citrus accessions was estimated using six decamer RAPD primers. Five primers generated reproducible and easily storable RAPD profiles with a number of amplified DNA fragments ranging from nine to 12 ,the primer OPA – 17 was negative results . The total number of amplicons detected was 50, including unique bands reached seven polymorphism were 34,this represents a level of polymorphism of 68.33% and an average number of 6.8 polymorphic bands per primer. a maximum numbers of amplicons was amplified with primer OPA-18 reached 12 while the minimum number of fragments was amplified with primers OPA-12 and OPN-16 reached 9 respectively. The highest number of polymorphic bands reached 8 were obtained with primer OPN-16 and OPA-01respectively, while the highest number of monomorphic bands reached 3 was obtained with primer OPA-12 and OPS-147 with percentage reached 33.33% and 30 respectively. RAPD markers detected genetic distance and similarity , a maximum genetic distance value was observed between sour orange (SO) and sweet orange (OR) reached 0.578 with less similarity value reached 42%, a minimum genetic distance value was observed between sweet orange (OR) and mandarin (MA) reached 0.316 with high similarity value reached 69% . The similarity matrices were employed in the cluster analysis to generate a dendrogram using the UPGMA method. The cluster tree analysis showed that the citrus species were broadly divided into two main groups A and B. A group including two species were troyercitronge (TC) and sour orange (SO) with genetic similarity reached 56%. B group was divided into two sub-cluster B1 and B2 with genetic similarity reached 51%. The first sub-cluster (B1) including only citrone(CI) species but the second sub-cluster (B2) divided into two groups( B2A and B2B),the first group (B2A) included sweet orange (OR) and mandarin (MA) with high genetic similarity reached 69%, and second group (B2B) included volkamer lemon (VL) species only.