ARS | Publication request: Genomic in situ hybridization (GISH) analysis of the North and Central American hexaploid wild potato species

Submitted to: European Association for Potato Research
Publication Type: Abstract Only
Publication Acceptance Date: April 1, 2011
Publication Date: July 24, 2011
Citation: Pendinen, G., Spooner, D.M., Jiang, J., Gavrilenko, T. 2011. Genomic in situ hybridization (GISH) analysis of the North and Central American hexaploid wild potato species [abstract]. European Association for Potato Research. p. 83.

Technical Abstract: About 70% of the approximately 100 wild potato (Solanum L. section Petota Dumort.) species are diploid (2n = 2x = 24), with the rest tetraploid (2n = 4x = 48), hexaploid (2n = 6x = 72), and a few rare triploid and pentaploid populations. Determination of the type of polyploidy and the development of the genome concept for species of the section Petota has been based on the analysis of chromosome pairing in species and their hybrids, molecular markers, DNA sequences, and most recently on GISH for Mexican tetraploid species. In the taxonomic treatment of Hawkes (1990) all hexaploid Mexican species belong to series Demissa. According to a classic five genome hypotheses of Matsubayashi (1991), all members of series Demissa are strict allopolyploids with genome formulae AADDD’D’, and the diploid Mexican species S. verrucosum was suggested as the putative contributor of the A genome whereas donor(s) of the D genome(s) are unknown. Our genomic in situ hybridization (GISH) analyses hybridized meiotic and mitotic chromosomes of S. demissum, S. hougasii, S. iopetalum, and S. schenckii with differentially labeled DNA of their putative progenitors: 1. AA genome diploids S. verrucosum and S. stenotomum, 2. BB genome diploids S. bulbocastanum, S. ehrenbergii, S. jamesii, 3. PP/ApAp genome diploids S. andreanum, S. pascoense, S. piurae, 4. AABB genome tetraploid S. stoloniferum, 5. AAAaAa genome tetraploid S. acaule. GISH data support S. hougasii, S. iopetalum, and S. schenckii as strict allopolyploids, containing genomes AA, BB, and the third genome most likely related to PP. However, the three genomes S. demissum (and S. acaule) are highly similar, most likely homologous or highly homologous to AA. Thus, GISH data support S. demissum as an autoplolyploid rather than an allopolyploid. Our results provide support for a recent division of the Mexican hexaploid species into two groups (Acaulia Group and Iopetala Group) as outlined above.