Genetic diversity and structure of Capparis spinosa L. natural populations using morphological and molecular markers

Capparis spinosa is an orphan shrub widely distributed in various landscapes in the Mediterranean basin and in Asia. The medicinal and culinary value of its products has gained the scientific interest, however due to small-scale efforts for caper cultivation, caper parts are largely collected uncontrollably from wild germplasm, exposing natural populations to bottleneck events. Assessment of the species' genetic diversity is pivotal for the design of conservation schemes. DNA barcoding of 8 C. spinosa populations, collected from various landscapes in Greece was verified by ITS2, matK and trnL-trnF markers and morphological characterization revealed significant dif-ferences regarding the leaf length, width, weight, and the length of internodes (Wilk's lambda = 0.002, p < 0.001), as well as significant correlations between the population's genotype and the internodal length (R=0.4, p < 0.05). Molecular genetic characterization with 8 SRAP and 8 SCoT markers revealed low diversity indices (Shannon's I= 0.28, h=0.19). The Analysis of Molecular Variance (AMOVA) suggests that 67% of the variability is detected within each population (p < 0.001), while STRUCTURE analysis inferred the existence of 3 distinct populations, indicating admixtures in 4 populations from southern Greece. The results of this study corroborate the necessity for thorough caper germplasm characterization and deployment of a conservation strategy of Greek wild pop-ulations to safeguard the species' diversity.