Cai, Danying , Teng, Yuan Wen , Rodriguez, F. , Mueller, Lukas , Bonierbale, Meredith , Spooner, David M. .
Complex multiple reticulate origins of potato polyploids.
Solanum section Petota is composed of approximately 100 tuber-bearing species, distributed from North to South America, and consists of diploids (2n = 2x = 24), triploids, tetraploids, to hexaploids (2n = 6x = 72). Varying taxonomic treatments by different authors reflect its difficult taxonomic status. Prior phylogenies constructed with the nuclear ortholog DNA sequences GBSSI (waxy) and nitrate reductase demonstrated both autopolyploid and allopolyploid origins of the tetraploids and hexaploids. The present study greatly expands these investigations with the use of six conserved orthologous set (COSII) nuclear loci in a total of 54 accessions of 11 tetraploid or hexaploid species in four traditional series Acaulia (S. acaule, S. albicans); Conicibaccata (S. agromonifolium, S. colombianum, S. moscopanum); Demissa (S. demissum, S. hougasii, S. iopetanum, S. schenckii); and Longipedicellata (S. hjertingii, S. stoloniferum); examined along with 23 accessions of 21 diploid species representative of all three main clades in sect. Petota, and S. etuberosum as outgroup. Our results confirm some of the GBSSI and nitrate reductase results, but also demonstrate: 1) some accessions within traditional morphospecies have originated from different parents; 2) some accessions within traditional morphospecies have lost alleles that are retained in other accessions [incomplete lineage sorting]; and 3) the cladistic structure with some COSII is more complex than prior studies, grouping the polyploids into separate clades. These results confirm prior studies by Rodriguez et al. in 2009 showing different evolutionary histories with different genomic regions, support a complex reticulate history of the polyploids, differential allele loss in some accessions, and explain the extensive taxonomic difficulty in sect. Petota.
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1 - Zhejiang University, Department of Horticulture, Institution of Fruit Science, 268 Kaixuan Road, Hangzhou, Zhejiang, 310029, China
2 - Zhejiang University, Horticulture, Institution of Fruit Science, 268 Kaixuan Road, Hangzhou, Zhejiang, 310029, China
3 - University of Wisconsin Madison, Horticulture Department, 1575 Linden Dr., Madison, Wisconsin, 53706-1590, USA
4 - Boyce Thompson Institute for Plant Research, Tower Road, Ithaca, NY, 14853-1801, USA
5 - International Potato Center (CIP), Germplasm Enhancement and Crop Improvement , Apartado 1558, La Molina, Lima, 12, Peru
6 - USDA, Agricultural Research Service, Horticuluure, 1575 Linden Drive, Madison, Wisconsin, 53706-1590, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 556B/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 4:30 PM