Preliminary investigations into the phylogenetic relationships in the genus Erica L.

[摘要] ENGLISH ABSTRACT: Erica is a genus of about 860 species world wide, with 700 of these found in South Africa'ssouthwestern and southern Cape, making it by far the most speciose genus in the Cape FloristicRegion. This poses a particular challenge in the construction of a molecular phylogeny of thegenus. The choice of suitably variable gene regions is a crucial decision on which the successfulphylogenetic reconstruction of this important genus is critically dependent.The aim of this project was therefore to determine which DNA regions, both chloroplast andnuclear, would be sufficiently variable to give adequate informative characters that may be usefulat the species level phylogenetic reconstruction. A subset of 30 species, representing the range ofmorphological diversity and pollinator preference within Erica, was selected for study. For each ofthese species the variability in eight chloroplast regions (trnL-F, matK, trnS-G, rps12- rpl20, psbAtrnH,trnC-D, rps4-trnT and trnT-L) and the nuclear ITS region was investigated.The psbA-trnH, trnC-D, rps4-trnT and trnT-L chloroplast regions were found to be problematic toamplify and to possess too few Parsimony Informative Characters to be of use in phylogeneticreconstruction. Four of the chloroplast regions, trnS-G, trnL-F, matK and rpS12-rpL20 and thenuclear ITS region could be amplified and sequenced with success. The ITS region was found tobe reasonably variable, with the chloroplast genes showing less variability.The DNA extraction method employed showed itself to be of critical importance in the success ofthe study. Two DNA extraction protocols, both modified from the original Doyle and Doyle (1987)method, were tested. The one included double the amount of β-mercaptoethanol andPolyvinylpyrrolidone (PVP) and the other included an extended phenol: chloroform: isoamylalcoholstep. These variables, together with the effectiveness of these methods on fresh vs. silica driedplant samples, were investigated to determine which of the two would yield high quantities andqualities of DNA and result in the best method for the extraction of DNA from Erica species.

[发布机构] Stellenbosch University