Application of RAPD and ISSR markers to analyse molecular relationships in Grevillea (Proteaceae)

Abstract

The potential of RAPD and ISSR markers to construct molecular relationships of Grevillea was evaluated with 23 RAPD and 12 ISSR primers. The 16 genotypes representing 12 species and 3 subspecies of Grevillea were sampled from the collection of the Mt Anann Botanic Garden, NSW. RAPD and ISSR assays generated a total of 401 RAPD and 280 ISSR fragments. High frequencies of polymorphisms, 99.39% for RAPD and 99.51% for ISSR, were detected by both markers. Three statistical approaches were employed to construct phylogenetic relationships from combined RAPD and ISSR data. Cluster analysis by the unweighted pair group method (UPGMA) of Jaccard's similarity and Neighbour-Joining analysis of total character difference generated dendograms with similar topology. Parsimony analysis also generated a tree that was in broad agreement with the two dendograms. The phylogenetic trees divided the Grevillea species studied into three groups. Group A consisted of G. buxifolia subsp. buxifolia, G. phylicoides and G. sphacelata. In group B, G. mucronulata was grouped together with G. montana, while G. diffusa, G. humilis, G. linearifolia, G. molyneuxii, G. oldei, G. sericea and G. speciosa formed group C. This molecular result was comparable to groupings suggested by a previous author (Makinson 2000) based on morphological characteristics. However, in contrast to the morphological taxonomy, molecular phylogeny suggests that G. oldei and G. speciosa belong to the same subgroup sensu Makinson (2000), whereas G. linearifolia and G. molyneuxii should not be placed in their originally suggested subgroups sensu Makinson (2000). The present study is the first published report on molecular relationships of Grevillea and can be considered as an initial point for further research on the genetic relationships and evolution of Grevillea.