Systematics Section / ASPT
Rodriguez, F. , Spooner, D. M. .
Nitrate reductase phylogeny of wild potatoes (Solanum section Petota) using all three introns.
Solanum Petota is taxonomically difficult. It has tremendous morphological, physiological, and ploidy variation with diploids (2n = 24) to hexaploids (2n = 72). There is much disagreement regarding species boundaries, number of series and affiliation of species to series, and hypothesis of hybridization. The latest estimate is for 180 species in the section. We previously reported phylogenetic results of sect. Petota using introns 1 (74 bp) and 2 (847 bp) and the intervening exon (141 bp) of nitrate reductase (NIA). We here add data from intron 3 (436 bp) and flanking exons (132, 659 bp), for a total (aligned) nitrate reductase dataset of 2958 bp for 53 species. With cloned sequences of the polyploids, we analyzed a total of 207 sequences. We compare these results to a previous chloroplast DNA restriction site phylogeny of section Petota that defined four clades, and an unpublished waxy gene phylogeny that defined a similar three clades (1+2), 3, and 4 relative to the cpDNA results. As expected, most phylogenetic information is in the intronic regions, but we had considerable difficulty aligning sequences in the larger intron 2. Phylogenetic results from introns 1+3 define the same clades (1+2; 3, and 4) as waxy and similar to cpDNA, but intron 2 analyzed alone an in combination with all other data introduce discordant results. Intron 2 lowers the consistency index relative to all sequences together. NIA (1+3) of all taxa, including polyploids, supports, like waxy, allopolyploid origins for members of series Conicibaccata and Demissa (except S. demissum) from clades 3 + 4, and series Longipedicellata from members of clades (1+2) + 4, and members of other series (and S. demissum from within clade 4.
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1 - University of Wisconsin Madison, Horticulture Department, 1575 Linden Dr., Madison, Wisconsin, 53706-1590, USA
2 - USDA-ARS, University of Wisconsin, Department of Horticulture, 1575 Linden Drive, Madison, Wisconsin, 53706, USA
wild potatoes phylogeny
Solanum section Petota
Presentation Type: Oral Paper
Location: Salon G - Austin Grand Ballroom/Hilton
Date: Wednesday, August 17th, 2005
Time: 2:00 PM