Genetic Diversity of Fissidens dubius P. Beauv. Based on ISSR Data

Fissidens dubius P. Beauv., a species of Fissidens Hedw. belonging to Fissidentaceae (Musci), is widely distributed and shows high morphological variation. To understand its genetic diversity and structure, 14 populations of F. dubius collected from Zhejiang, Fujian, Guangxi, Sichuan and Liaoning Provinces were tested using ISSR markers. Of the 56 ISSR primers tested, 12 were selected to amplify the DNA from 101 samples of the 14 populations, with 259 clear and repeatable bands obtained. We found 248 polymorphic loci, with 95.75% polymorphic loci, a Nei's genetic diversity index of 0.2327, and a Shannon's information index of 0.3701. The populations of F. dubius had a high level of genetic diversity. The genetic differentiation index (Gst) of the 14 populations was 0.7078, the gene flow among these populations was 0.1864, and the majority of genetic variation (72.01%) existed among populations, with only 27.99% existing within populations. These results demonstrated that F. dubius had obvious genetic differentiation among populations. Based on ISSR data, the dendrogram with a grouping threshold at a genetic distance of 50 showed that populations could be divided into six groups (G1-G6):Group 1 included eight populations from Zhejiang Province, except the Jinhuabeishan population, Group 2 included the Jinhuabeishan population, Group 3 included the Fujian populations from Wuyishan and Tianbaoyan, Group 4 included populations from Huaping of Guangxi Province, Group 5 included Longchi population of Sichuan Province, and Group 6 included Bashilazi of Liaoning Province. Our analyses showed geographical genetic differentiation among populations and genetic differentiation relative to habitat heterogeneity within populations of F. dubius.