Phylogeny, phylogeography and genetic diversity of the Pisum genus

Abstract

The tribe Fabeae (formerly Vicieae) contains some of humanity?s most important grain legume crops, namely Lathyrus (grass pea/sweet pea/chickling vetches; about 160 species); Lens (lentils; 4 species); Pisum (peas; 3 species); Vicia (vetches; about 140 species); and the monotypic genus Vavilovia. Reconstructing the phylogenetic relationships within this group is essential for understanding the origin and diversification of these crops. Our study, based on molecular data, has positioned Pisum genetically between Vicia and Lathyrus and shows it to be closely allied to Vavilovia. A study of phylogeography, using a combination of plastid and nuclear markers, suggested that wild pea spread from its centre of origin, the Middle East, eastwards to the Caucasus, Iran and Afghanistan, and westwards to the Mediterranean. To allow for direct data comparison, we utilized model-based Bayesian Analysis of Population structure (BAPS) software on 4429 Pisum accessions from three large world germplasm collections that include both wild and domesticated pea analyzed by retrotransposon-based markers. An analysis of genetic diversity identified separate clusters containing wild material, distinguishing Pisum fulvum, P. elatius and P. abyssinicum, supporting the view of separate species or subspecies. Moreover, accessions of domesticated peas of Afghan, Ethiopian and Chinese origin were distinguished. In addition to revealing the genetic relationships, these results also provided insight into geographical and phylogenetic partitioning of genetic diversity. This study provides the framework for defining global Pisum germplasm diversity as well as suggesting a model for the domestication of the cultivated species. These findings, together with gene-based sequence analysis, show that although introgression from wild species has been common throughout pea domestication, much of the diversity still resides in wild material and could be used further in breeding. Moreover, although existing collections contain over 10,000 pea accessions, effort should be directed towards collecting more wild material in order to preserve the genetic diversity of the species.Peer reviewe

Molecular analysis of temporal genetic structuring in pea (Pisum sativum L.) cultivars bred in the Czech Republic and in former Czechoslovakia since the mid-20th century

“…The collection is guided according to general rules of the National Programme for Plant Genetic Resources of the Czech Republic and passport data are available at http://genbank.vurv.cz/genetic/ resources. We have used the subset (175 accessions) of Czech/Czechoslovak accessions bred over the last 70 years, which has already been integrated into European legume diversity projects (Smýkal et al 2008(Smýkal et al , 2011. Of them, 115 accessions were smooth-seeded, white flowering, dry seed peas and 60 accessions were coloured flowering, fodder peas.…”

“…The selection of loci was done according to the previous analysis (Smýkal et al 2008(Smýkal et al , 2011. The SSR and RBIP marker PCR amplifications and gel analysis were performed as described in Smýkal et al (2008).…”

“…While the number of species per unit area of agricultural land is lower than in most of the natural ecosystems, agriculture has also produced amazing genetic diversity (some species with more than hundred thousand varieties) (Hammer et al 2003). In the case of pea (Pisum sativum L.) being domesticated about 10 000 years ago (Ambrose 1995; Ellis 2011), followed by centuries of selection and breeding, this process resulted in thousands of varieties, many of which have survived and are maintained in numerous germplasm collections worldwide (Smýkal et al 2011). Already in the period of rediscovery of Mendel's work, many biologists and plant breeders pointed out to the danger of losing genetic diversity (Proskowetz 1890;Schindler 1890).…”

“…On the other hand, high mutation rate and homoplasy of SSRs (Cieslarová et al 2011b) make them inapplicable for studies on higher taxonomic levels. Retrotransposon-based amplified polymorphism (RBIP) developed for pea (Flavell et al 2003) found its use not only in phylogenetic studies, but also for pea germplasm collections (Smýkal et al 2008(Smýkal et al , 2011Jing et al 2010;Ellis 2011). …”

Grain legume crop history among Slavic nations traced using linguistic evidence

“…and vetches (Vicia spp.) are regarded as globally the most important (Smýkal et al 2010). All of them originated in Near Eastern, Mediterranean and Central Asian centres of diversity (Zeven & Zhukovsky 1975).…”