|Ballard, Jr., Harvey|
Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: 7/15/2003
Publication Date: 1/15/2004
Citation: Spooner, D.M., Stephenson, S.A., Ballard, Jr., H.E., Polgar, Z. 2004. DNA sequences of single-copy waxy gene support allopolyploid origins of wild potatoes (Solanum section Petota) [abstract]. Plant and Animal Genome Conference. p.79. Interpretive Summary:
Technical Abstract: Hybridization and introgression are believed to be common in wild potatoes (Solanum sect. Petota). Thirty percent of wild potato species are polyploid. DNA sequence data can be useful to unravel allopolyploid origins because of good homology assessment and possible retention of both diploid progenitor copies in the hybrid. This study used DNA sequences from the single-copy nuclear gene waxy or GBSSI, to investigate hybrid origins of presumed allopolyploid species in tetraploid Solanum series Longipedicellata (genome designation AB); hexaploid series Demissa (genome designation A1A4 (BB, or CC, or DD), or ADD (bdgs); tetraploid series Acaulia (AAa), and hexaploid series Acaulia (AAaX). Cladistic analyses of waxy DNA sequences completely concur with prior chloroplast DNA (cpDNA) restriction site data (American Journal of Botany, 84: 671-685) regarding outgroup relationships. When just the diploids are analyzed, waxy is concordant with the four-clade cpDNA results except clade 1 (Mexican diploids), and clade 2 (S. bulbocastanum and S. cardiophyllum) species are members of the same clade, and clade 3 (Piurana clade) is basal. When the cloned waxy sequences from the polyploids are included in cladistic analyses, divergent copies sometimes fall into two clades, and support a diversity of allopolyploid origins to include hybrids between members of clades 1 or 2 and clade 4 (series Longipedicellata), and between members of clade 3 and clade 4 (ser. Demissa). Some cloned sequences fall completely within different branches of clade 4 (ser. Demissa, ser. Longipedicellata). These results explain the great taxonomic difficulty distinguishing these series, and defining species within them.