Molecular Assessment of Genetic Diversity and Genetic Structure of Rhanterium epapposum Oliv. in Scarce Populations in Some Regions of Western Saudi Arabia

Abstract

Rhanterium epapposum Oliv. is a perennial medicinal shrub growing mainly in desert habitats in the Arabian Peninsula. In western Saudi Arabia, the remaining few populations of this species are exposed to many threats, including overcutting, overgrazing, and recently, increasing human activities. These threats are predicted to be exacerbated by the advancement of aridification caused by climate change. The conservation and recovering of the diminished populations of R. epapposum necessitate measurement of their genetic diversity and genetic differentiation. To accomplish this objective, we tested 150 simple sequence repeat (SSR) primer pairs, with which 40 polymorphic loci were identified. These polymorphic loci were used to determine the population genetics of 540 plant accessions sampled from a total of 45 populations of R. epapposum located in 8 sites in western Saudi Arabia: Wadi Khurieba, Wadi Al Khamas, Gebel Al Twaal, Al Asaafer, Wadi ALHamda, Wadi Al Nassayeif, Wadi Qaraba, Wadi Kuliayah, and Wadi Dahban. Low levels of genetic diversity were found in all populations (the values of the PPL ranged between 52.5 and 15) along with a declined value of HT (0.123) and a considerable inbreeding value (F = 0.942), which confirmed a noticeable shortage of heterozygotes. High genetic differentiation among the populations and a low value of gene flow are indicative of high isolation among the R. epapposum populations, which has caused a severe deficiency in gene migration. The data obtained herein inspire several recommendations for conservation and retrieval of the existing populations, including seed banks, restoration of diminished populations, and monitoring and prevention of cutting and grazing activities at threatened sites. All of these measures are urgently required to avoid imminent extinction.

Population Genetics, Genetic Structure, and Inbreeding of Commiphora gileadensis (L.) C. Chr Inferred from SSR Markers in Some Mountainous Sites of Makkah Province

“…In this study, all the genetic diversity variables of C. gileadensis showed a modest to extreme decline in measurements among all the enduring populations analysed and was in agreement with other studies on closely related plant species of Burseraceae. This indicates an extensive decline in gene diversity and meets the corresponding severe environmental circumstances [28][29][30][31][32][33][34] confirmed by the comparison of the high genetic differentiation F ST values, which measured for C. gileadensis (F ST = 0.896) with other rare plant species in similar plant habitats in South Sinai, and they revealed considerable values of genetic differentiation, e.g., Primula boveana (F ST = 0.737) [35] and Cotoneaster orbicularis (F ST = 0.634) [32].…”

“…The polymorphic primer tests were performed for all sampled individuals (Table S1). A master mix for PCR trials was prepared according to procedures outlined in [34]. PCR tests were carried out using a C1000 Thermal Cycler (BioRad, Hercules, CA, USA).…”

Introduction to the Special Issue of Plants on “Advances in Plant Reproductive Ecology and Conservation Biology”

“…Second, the hypothesized patterns of genetic diversity were not often recovered. Greater than anticipated genetic variation was found in S. floridana, I. lacustris, and E. capitatum, but only minimal differences were identified between dioecious and cosexual species of Solanum, C. gileadensis, D. foliosa, and for species used in Salep [2,3,[5][6][7]. Collectively, these studies demonstrate the important role that field and laboratory studies play in ensuring a comprehensive understanding of population biology.…”