(GTG)5-rep-PCR demonstrates a clear cut genetic differentiation of Candidatus Liberibacter asiaticus isolates infecting mandarin trees in Hormozgan and Sistan and Baluchestan provinces of Iran

Huanglongbing (HLB) is one of the most destructive diseases of citrus worldwide. The disease keeps spreading in several citrus-growing areas of southern Iran. The potential of (GTG)5-rep marker in revealing the genetic diversity of geographic isolates of Candidatus Liberibacter asiaticus was evaluated in the present study. Twenty-one HLB-infected samples collected from the Hormozgan and Sistan and Baluchestan provinces were used in the trial. PCR with the (GTG)5 primer produced 16 scorable bands, of which nearly 100% were polymorphic among or within the populations. The most observed variation resided within (80.56, P < 0.10) and a substantially less (19.44, P < 0.10) between the populations. The isolates were distributed in two main (A and B) clusters, each consisting of several subgroups. Group A included Sistan and Baluchestan and Hormozgan isolates and the group B embraced Hormozgan isolates. Based on pairwise genetic differences, the Haji Abad and Hashtbandi populations exhibited the highest between-population variation, and the Siahoo, Hashtbandi, Nikshahr, Haji Abad, and Sarbaz showed the greatest within-population variation. The first three coordinates of the principal coordinate analysis explained more than 72.39% of the variation among or within the populations. The first two coordinates explained 58.20% of band variation in plotting, and the first and third coordinates explained 55.54% of band variation. These results may be inferred that the Hormozgan populations might have diverged from the Sistan populations, or both might have originated separately from an initial or parental population possessing a high genetic diversity.