Study On The Genetic Diversity Of Osmanthus Fragrans Cultivars By AFLP Markers

Osmanthus fragrans Lour., a species in the family Oleaceae, are classified into four groups (Fragrans Group, Latifolius Group, Thunbergii Group, and Aurantiacus Group) according to morphological characteristics. Little work has been done concerning molecular marker based methods of O. fragrans cultivar classification. In this study, a number of O. fragrans cultivars were analyzed using the AFLP technique. The results are as follows:1. Improvements were made to an existing O. fragrans genomic DNA extraction technique; high quality DNA strands/fragments were obtained; an AFLP protocol suitable for O. fragrans cultivar classification was set up; clear AFLP fingerprints were attained.2. An PstI/MseI enzyme mix was used to screen 22 pairs of AFLP primers, 6 of which could generate reproducible polymorphic fragments and were used in an AFLP investigation of 22 O. fragrans cultivars and three Osmanthus species. 171 bands were detected, of which 104 were polymorphic. Nei's genetic distance was calculated between pairs of cultivars/species; UPGMA cluster analysis was performed to construct a dendrogram. From the dendrogram, we knew some cultivars of Latifolius Group and Fragrans Group had remotely relationship comparing with Thunbergii Group and Aurantiacus Group. The results showed that O. fragrans cultivar relatedness was positively correlated with flower color similarity. The AFLP based classification was not entirely consistent with the traditional, morphology-based classification.3. An EcoRI/MseI enzyme mix was used to conduct AFLP analysis of 43 cultivars. The results showed that the cultivars possessed high levels of genetic diversity. Of the 228 bands that were successfully amplified using 5 primer combinations, 131 were polymorphic. The UPGMA cluster analysis of the AFLP data revealed that O. fragrans cultivars of the Guilin region formed a distinct subgroup and flower color was a viable classification criterion. There were also some discussions regarding phylogeny of the four O. fragrans cultivar groups and O. fragrans cultivar classification systems.