AFLP analysis reveals a lack of phylogenetic structure within Solanum section Petota

Abstract

BackgroundThe secondary genepool of our modern cultivated potato (Solanum tuberosum L.) consists of a large number of tuber-bearing wild Solanum species under Solanum section Petota. One of the major taxonomic problems in section Petota is that the series classification (as put forward by Hawkes) is problematic and the boundaries of some series are unclear. In addition, the classification has received only partial cladistic support in all molecular studies carried out to date.The aim of the present study is to describe the structure present in section Petota. When possible, at least 5 accessions from each available species and 5 individual plants per accession (totally approx. 5000 plants) were genotyped using over 200 AFLP markers. This resulted in the largest dataset ever constructed for Solanum section Petota. The data obtained are used to evaluate the 21 series hypothesis put forward by Hawkes and the 4 clade hypothesis of Spooner and co-workers.ResultsWe constructed a NJ tree for 4929 genotypes. For the other analyses, due to practical reasons, a condensed dataset was created consisting of one representative genotype from each available accession. We show a NJ jackknife and a MP jackknife tree. A large part of both trees consists of a polytomy. Some structure is still visible in both trees, supported by jackknife values above 69. We use these branches with >69 jackknife support in the NJ jackknife tree as a basis for informal species groups. The informal species groups recognized are: Mexican diploids, Acaulia, Iopetala, Longipedicellata, polyploid Conicibaccata, diploid Conicibaccata, Circaeifolia, diploid Piurana and tetraploid Piurana.ConclusionMost of the series that Hawkes and his predecessors designated can not be accepted as natural groups, based on our study. Neither do we find proof for the 4 clades proposed by Spooner and co-workers. A few species groups have high support and their inner structure displays also supported subdivisions, while a large part of the species cannot be structured at all. We believe that the lack of structure is not due to any methodological problem but represents the real biological situation within section Petota.

Persistence over time, overlapping distribution and molecular indications of interspecific hybridization in wild potato populations of Northwest Argentina

“…Morphological variability has also been observed in some grl accessions regenerated at the Genebank (Clausen, unpublished data). Moreover, Erazzú et al (1999), in studying crosscompatibility relations between and within Ispizúa's (1994) morphological groups, detected pre-zygotic breeding barriers, both within two of the groups and between the three of them. They consisted in the arrest of pollen tube growth at four different sites: stigma, first third, middle and second third of the style.…”

“…Periodically, these accessions are regenerated and evaluated ex situ in the facilities of the Genebank. In a previous work, Ispizúa (1994) observed morphological variability in spg accessions from different departments of Salta Province and proposed to arrange them into three morphological groups. These groups comprised populations from (a) Quebrada de Escoipe (with narrow leaflets of reduced length, acuminate leaflet apex, purple corolla and low pubescence), (b) Quebrada Calchaquí (with wide leaflets, long, acute leaflet apex, light violet corolla with violet shades and white acumens, very pubescent) and (c) Quebrada de Belén (with wide leaflets, long, acute leaflet apex, light violet corolla, low pubescence).…”

Changes in micro RNA expression in a wild tuber-bearing Solanum species induced by 5-Azacytidine treatment

“…Even though molecular analyses have determined relationships among species, they are incongruent, especially to resolve the South American species. There are several examples in which morphologically related species show no such proximity at molecular level or, conversely, molecular data that group together species showing stark morphological differences (Spooner and Castillo 1997;Jacobs et al 2008). The development of molecular markers has allowed surveying the genetic base of the morphological variability naturally found in wild potato populations.…”

Mobilization, conservation and study of cultivated and wild potato genetic resources

“…Вопросам классификации клубненосных видов Sola num L., решаемым с помощью молекулярного и геномного анализа, посвящены работы (Jacobs et al, 2008(Jacobs et al, , 2011Bradeen, Haynes, 2011;Spooner et al, 2014;MachidaHirano, 2015). Родственные взаимоотношения и таксономия ви дов картофеля продолжают оставаться дискуссионными.…”