Genetic diversity analysis of Rhanterium eppaposum Oliv. by ISSRs reveals a weak population structure

Rhanterium eppaposum Oliv. (Arfaj) the national plant of Kuwait, is a perennial bushy shrub and the national flower of Kuwait. It is one of the most palatable forage plants and an excellent performer for desert rehabilitation. Due to several anthropogenic activities and climate change, this native plant has suffered severe degradation. In order to formulate conservation strategies, the genetic diversity of Rhanterium, was assessed by inter simple sequence repeat (ISSR) markers. A total of 93 wild landraces distributed in six remote locations in Kuwait were tested using 17 primers (PIC = 0.31; polymorphism = 92.8 %) that produced 195 unambiguous and reproducible bands. Overall, diversity indices were high enough (Nei's gene diversity (h') - 0.286; Shannon's diversity index - 0.414) for these populations. AMOVA test returned a fixation coefficient (F_ST) of 0.116 (p = 0.0) with higher genetic variations detected within (88 %) the populations as compared to among (12 %) the populations. Satisfactory levels of genetic differentiation (G_ST = 0.186; G’_ST = 0.250; D’ = 0.295) were recorded for R. eppaposum with a gene flow (N_M) maintained at 1.9. The maximum genetic distances were observed between Maqwa and Mina Abdulla (Ds- 0.158; F_ST- 0.228) whereas minimum was between Al Kabd and SANR (Ds - 0.06; F_ST- 0.05). A weak Mantel's correlation (r² - 0.139; P = 0.014) between the six populations was also recorded. A narrow population structure was observed through the PCoA (2 groups), STRUCTURE (2 groups, K = 2) and SPLIT decomposition (1 cluster). The high genetic diversity within the populations are encouraging, however the low genetic differentiation raises concerns. The population structure should be improved by planting genetically diverse genotypes in areas of very low diversity to broaden its genetic base.