Abstract
Ziziphus spina-christi (sidr) is a shrub, sometimes a tree, native to a vast area of Africa stretching from Mauritania to West Africa. In the Kingdom of Saudi Arabia, it is an exotic medicinal plant for many diseases. The aim of this study was to assess the genetic diversity within and among 34 accessions of Z. spina-christi collected from different regions of Saudi Arabia. The amplification of genomic DNA with 11 inter-simple sequence repeat (ISSR) primers yielded 105 scorable loci, of which 93.4% were found to be polymorphic. The observed number of alleles (na), effective number of alleles (ne), Nei's gene diversity (h) and genetic diversity estimated by Shannon's information index (I) were 1.93, 1.44, 0.26 and 0.41, respectively. The total genetic diversity, H
t
(0.266 ± 0.0289) was close to the average intrapopulation genetic diversity, H
s
(0.2199 ± 0.0216). A high level of gene flow (N
m
= 2.37) between populations, reflecting high genetic differentiation (G
st
= 0.1739). The analysis of molecular variance showed that the maximum value of genetic variation was found within populations (90%), whereas a low value of genetic variance was observed among populations. The analysis using the unweighted pair-group method with arithmetic averages clustered the population from Farasan Island as an out-group due to its geographical origin. The obtained results demonstrate that the ISSR markers may be used for evaluation of the genetic diversity due to their efficiency in revealing polymorphism even in closely related germplasm and may help in Ziziphus genome analysis.