On the origin and dispersal of cultivated spinach (Spinacia oleracea L.)

Abstract

Spinach (Spinacia oleracea L.) is an economically important crop that is cultivated and consumed worldwide. Spinach is interfertile with the wild species S. tetrandra Steven ex M. Bieb. and S. turkestanica Iljin that therefore are presumed to include the most likely crop ancestor. Here we studied variation in 60 Single Nucleotide Polymorphisms (SNP) previously identified in S. oleracea to address the issue of crop ancestry and domestication region. For this purpose we investigated 95 accessions, including 54 spinach landraces from a wide geographic area in Europe and Asia and 16 S. tetrandra and 25 S. turkestanica populations of which the majority had only recently become available. Compared to S. tetrandra substantially higher levels of amplification success and higher levels of variation were detected for S. turkestanica, indicating that S. oleracea is genetically closer to S. turkestanica than to S. tetrandra. Our phylogenetic and population structure analysis supported the conclusion that S. turkestanica is the most likely ancestor of cultivated spinach. In addition, these analyses revealed a group of S. oleracea landraces from Eastern and Southern Asia with a strong genetic resemblance to S. turkestanica. This group includes landraces from Afghanistan and Pakistan, which are part of the native distribution range of S. turkestanica. The domestication of spinach may therefore have occurred more eastwards than generally assumed. Furthermore, our study provides support for the hypothesis that after domestication, spinach was introduced into China via Nepal. Additional collecting of spinach landraces is recommended in order to allow the more precise reconstruction of the crop migration routes.

Genome-wide simple sequence repeats (SSR) markers discovered from whole-genome sequence comparisons of multiple spinach accessions

“…Genetic grouping of spinach accessions based on SSR markers corresponded well with their geographical origin, domestication history, and pedigree. And the genetic clustering of accessions was similar to previous genetic diversity studies 26 , 47 .…”

“…Fingerprint data generated from PCR genotyping was used to assess the genetic diversity and population structure of the spinach accessions. The population structure and phylogeny assignment performed with allele scores of 34 SSR markers in this study distinguished the worldwide spinach germplasm accessions and the population group assignments were consistent with previous reports 26 , 47 . The accessions were subdivided into three main populations based on STRUCTURE analysis, and the phylogenetic analysis in MEGA and PCA analysis in TASSEL supports the three genetic clusters.…”

“…Spinach is believed to have migrated to China via Nepal during the seventh century, and later to Europe and very recently to the United States 25 . Recent studies were conducted to explore the genetic diversity of spinach germplasm, including the wild Spinacia species, and explore crop ancestry and domestication region that support migration of spinach to China via Nepal 26 . Both wild species are interfertile with the cultivated S. oleracea suggesting close genetic relation and recent domestication history 26 .…”

“…Recent studies were conducted to explore the genetic diversity of spinach germplasm, including the wild Spinacia species, and explore crop ancestry and domestication region that support migration of spinach to China via Nepal 26 . Both wild species are interfertile with the cultivated S. oleracea suggesting close genetic relation and recent domestication history 26 . The genetic evidence suggests that S. turkestanica is the progenitor of cultivated spinach 26 , 27 .…”

“…Both wild species are interfertile with the cultivated S. oleracea suggesting close genetic relation and recent domestication history 26 . The genetic evidence suggests that S. turkestanica is the progenitor of cultivated spinach 26 , 27 . There is a great opportunity to explore the genetic diversity of Spinacia accessions to use them in spinach improvement and by using molecular markers to perform fingerprinting, genetic characterization, marker-trait association, and to incorporate the new findings into molecular breeding programs for cultivar development.…”