Relative contribution of breeding system and species rarity to genetic differentiation in Inula racemosa Hook. f. (Asteraceae)

Genetic variation and breeding system of six populations of Inula racemosa (Asteraceae) from Kashmir Himalaya were assessed using random amplified polymorphic DNA (RAPD) markers and controlled pollination experiments. The 12 RAPD primers applied to 60 individuals generated a total of 116 discernible and reproducible PCR products, of which 51 (43.97%) were polymorphic. The Shannon's index (Ho) varied with population, ranging from 0.0897 to 1.2217, with an average value of 0.616. The mean diversity at species level was Hsp = 1.217. However, a high level of genetic differentiation among populations was detected based on different measures (Nei's genetic diversity analysis: Gst = 0.6341; AMOVA analysis: Fst = 0.6822). Using individual plants as the units of replication in controlled pollination experiments, autonomously-selfed and bagged emasculated capitulas set the lowest number of seeds/capitula and differed significantly from geitonogamously selfed capitulas (F = 11.44, p = 0.009), outcrossed capitulas (F = 9.65, p = 0.01), and open-pollinated controls (F = 8.55, p = 0.03) indicating a facultative xenogamy in I. racemosa. Low level of genetic diversity within populations and significant genetic differentiation among populations fit expectations for a rare species, although facultative xenogamy in which Xenogamy predominated and autogamy played an assistant role in I. racemosa may also affect the population genetic structure to some extent.