Search

Wild potato (Solanum L. sect. Petota Dumort.) species contain diploids (2n = 2x = 24) to hexaploids (2n = 6x = 72). J.G. Hawkes classified all hexaploid Mexican species in series Demissa Bukasov and, according to a classic five-genome hypothesis of M. Matsubayashi in 1991, all members of series Demissa are allopolyploids. We investigated the genome composition of members of Hawkes's series Demissa with genomic in situ hybridization (GISH), using labeled DNA of their putative progenitors having diploid AA, BB, or PP genome species or with DNA of tetraploid species having AABB or AA[A.sup.a][A.sup.a] genomes. GISH analyses support S. hougasii Correll as an allopolyploid with one AA component genome and another BB component genome. Our results also indicate that the third genome of S. hougasii is more closely related to P or a P genome-related species. Solanum demissum Lindl., in contrast, has all three chromosome sets related to the basic A genome, similar to the GISH results of polyploid species of series Acaulia Juz. Our results support a more recent taxonomic division of the Mexican hexaploid species into two groups: the allopolyploid Iopetala group containing S. hougasii, and an autopolyploid Acaulia group containing S. demissum with South American species S. acaule Bitter and S. albicans (Ochoa) Ochoa. Key words: GISH, polyploids, potato, Solanum section Petota. Les especes sauvages de la pomme de terre (Solanum L. sect. Petota Dumort.) comptent des especes diploides (2n = 2x = 24) jusqu'a des especes hexaploides (2n = 6x = 72). J.G. Hawkes a classifie toutes les especes hexaploides mexicaines au sein de la serie Demissa Bukasov et, selon l'hypothese classique des cinq genomes de M. Matsubayashi en 1991, tous les membres de la serie Demissa seraient allopolyploides. Les auteurs ont investigue la composition genomique de membres de la serie Demissa de Hawkes a l'aide de l'hybridation genomique in situ (GISH) avec des sondes d'ADN genomique provenant des especes ancestrales putatives a genomes AA, BB ou PP, ou encore provenant des especes tetraploides a genome AABB ou AA[A.sup.a][A.sup.a]. Les analyses GISH suggerent que le S. hougasii Correll serait un allopolyploide possedant un genome AA et un genome BB. Les resultats suggerent egalement que le troisieme genome du S. hougasii serait plus proche d' un genome P ou apparente au genome P. Le S. demissum Lindl., au contraire, possede trois jeux chromosomiques apparentes au genome A de base comme le suggerent les analyses GISH pour les especes polyploides de la serie Acaulia Juz. Ces resultats viennent appuyer une recente division taxonomique des especes hexaploides mexicaines en deux groupes : le groupe Iopetala d'allopolyploides comprenant le S. hougasii et le groupe Acaulia d'autopolyploides comprenant le S. demissum avec les especes sud-americaines S. acaule Bitter et S. albicans (Ochoa) Ochoa. Mots-cles: GISH, polyploides, pomme de terre, Solanum section Petota. [Traduit par la Redaction], Introduction Wild and cultivated potatoes, Solanum L. sect. Petota Dumort., contain over 230 tuber-bearing species according to the latest comprehensive taxonomic treatment by Hawkes (1990), but recent estimates propose about [...]

A major justification for taxonomic and biogeographic research is its assumed ability to predict the presence of traits in a group for which the trait has been observed in only a representative subset of the group. Such predictors are regularly used by breeders interested in choosing potential sources of disease and pest resistant germplasm for cultivar improvement, by genebank managers to organize the collection, and by germplasm collectors planning to gather maximum diversity. The present study tests taxonomic and biogeographic associations with 10,738 disease and pest evaluations, derived from the literature and genebank records, of 32 pest and diseases in five classes of organisms (bacteria, fungi, insects, nematodes, and virus). The data show that ratings for only Colorado potato beetle [Leptinotarsa decemlineata (Say)] and one pathogen (Potato M Carlavirus) are reliably predicted both by host taxonomy and climatic variables. While it is logical to initially take both taxonomy and geographic origin into account while screening genebank materials for pest and disease resistances, such associations will hold for only for a small subset of resistance traits. Based on these results, a more effective strategy than taxonomic and biogeographic prediction is probably careful screening of core collections.

Abstract: Thirty-six percent of the wild potato (Solanum L. section Petota Dumort.) species are polyploid, and about half of the polyploids are tetraploid species (2n = 4x = 48). Determination [...]

Chromosome pairing relationships within cultivated potato (Solanum tuberosum) and its wild tuber-bearing relatives (Solanum sect. Petota) have been interpreted by genome formulas, developed in the early 1900s, through techniques of classic meiotic analysis of interspecific hybrids. Here we reexamine potato genome hypotheses with the first phylogenetic anolysis of all major genomes of sect. Petota using cloned DNA sequences of the single-copy nuclear gene GBSSI (waxy). Our results provide the first molecular confirmation of allopolyploidy in wild potato. They both support prior hypotheses and identify novel genome origins never before proposed. The data will be useful to help design crossing strategies to incorporate wild species germplasm into cultivated potato.

The modern cultivated potato (Solanum tuberosum L.) was first recorded in Europe in the Canary Islands in 1567, but its origin has long been in dispute. Two competing hypotheses have proposed an 'Andean' area (somewhere from the Andean uplands from Venezuela to northern Argentina) or a lowland south-central 'Chilean' area, but the Andean origin hypothesis is today generally accepted. The identity of extant Canary Island potato landraces as exclusively of upland Andean origin is one part of a multicomponent argument that the European potato originated from there, rather than from Chile. We reassess these two competing hypotheses with nuclear microsatellite and chloroplast DNA analyses of 19 Canary Island landraces, 14 Andean landraces, 11 Chilean landraces, and two wild potato species as outgroups, and with chloroplast DNA data of 150 landraces from South America. Our molecular results document a wide variation of Andeanand Chilean-type cultivars on the Canary Islands and possible hybrids of the two. Our new data, integrated with historical, molecular, agronomic, and crossing data, support a hypothesis that there were multiple introductions of Andean and Chilean germplasm to the Canary Islands and that the early European potato was selected from Chilean introductions long before the late blight epiphytotics of the 1840s.

The National Epirubicin Adjuvant Trial (NEAT) and the BR9601 trial were designed jointly by English and Scottish investigators in 1994 and 1995 to determine the value of anthracyclines in the adjuvant treatment of early breast cancer. Adjuvant treatment of early breast cancer with epirubicin plus CMF was significantly superior over CMF alone in terms of relapse free survival and overall survival, and hence epirubicin plus CMF as an option for anthracycline-based adjuvant chemotherapy in women with early breast cancer was recommended.

A major justification for taxonomic research is its assumed ability to predict the presence of traits in a group for which the trait has been observed in a representative subset of the group. Taxonomy is regularly used by breeders interested in choosing potential sources of disease-resistant germplasm for cultivar improvement. We designed this study as an empirical test of prediction by associating resistance to white mold [caused by the fungal pathogen Sclerotinia sclerotiorum (Lib.) de Bary] to diverse potato (Solanum spp.) taxonomies and biogeography, using 144 accessions of 34 wild relatives of potato in Solanum sections Petota and Etuberosum. Tremendous variation for resistance to white mold occurs both within and among species. No consistent association was observed between white mold resistance and taxonomic series (based on a phenetic concept), clades (based on a cladistic concept), ploidy, breeding system, geographic distance, or climate parameters. Species and individual accessions with high proportions of whitemold-resistant plants have been identified in this study, but both often exhibit extensive variation and designation of either as resistant or susceptible must take this variation into account. Therefore, taxonomic relationships and ecogeographic data cannot be reliably used to predict where additional sources of white mold resistance genes will be found.

The final results of the European Study Group for Pancreatic Cancer 1 Trial are reported and the interim results are updated. It is concluded that adjuvant chemotherapy has a significant survival benefit in patients with resected pancreatic cancer, whereas adjuvant chemoradiotherapy has a deleterious effect on survival.

This study tests the genetic difference between landrace populations of Solanum tuberosum L. subsp. tuberosum and subsp. andigenum (Juz. & Bukasov) Hawkes using nuclear DNA microsatellites. Microsatellite loci were amplified in subsp. andigenum (35 accessions), subsp. tuberosum (35 accessions), and other cultivated and wild species (22 accessions). A total of 208 alleles were scored from 18 microsatellite loci spread throughout all 12 chromosomes of potato. Using an infinite allele model and a least squares method of analysis, microsatellite loci separated subsp. tuberosum from subsp. andigenum, and cultivated and wild species. These results support the genetic difference of these two populations and their recognition at some classification level., THE POTATO AND ITS WILD RELATIVES (S. sect. Petota Dumort.) harbor a wealth of both wild and cultivated tuber-bearing species distributed from the southwestern USA to central Argentina and adjacent [...]