Screening chloroplast, mitochondrial, and nuclear DNA sequences suitable for taxonomic studies in Actinidiaceae
2003
Cipriani, G. | Fiori, A. | Moroldo, M. | De Pauli, P. | Messina, R. | Testolin, R.
Comparison of DNA sequences is widely used in phylogenetic studies, and plant cells offer the possibility of studying both nuclear and cytoplasmic (chloroplast and mitochondrial) genomes. Recombination during sexual reproduction hampers easy interpretation of nuclear DNA data in phylogenetic reconstruction. In Actinidia, chloroplast DNA (cpDNA) is inherited through the male parent and the mitochondrial DNA (mtDNA) through the female one. We compared sequences from the three different genomes for evolutionary studies within the genus, which encompasses more than 60 species and some 100 taxa. We used a set of 23 taxa (18 different species), representative of all four sections in which the genus is currently split. As far as cpDNA is concerned, we used heterologous primers for the amplification of matK gene, two spacers (trnL-trnF and rbcL-atpA) and the intron of the rpl16 gene. As mitochondrial genes are highly conserved and as the mitochondrial genome undergoes re-arrangement, a large number of mtDNA sequences was screened in order to find those suitable for our taxonomic studies. Finally we focused our attention on the sequence encoding for the nuclear 5S rDNA subunit and its non-transcribed spacer (NTS). More than 100 informative characters were found in the cpDNA sequences screened up to now. The mtDNA genome, although extensively screened, gave only 39 informative characters. The analysis of the rDNA 5S+NTS has been less detailed. The preliminary data showed that 5S gene is approximately 120 bp long in Actinidia, as in most other species, and its sequence is highly conserved across species. The NTS is considerably more variable and mutations include base mutation and indels.
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