Establishing the A. E. Watkins landrace cultivar collection as a resource for systematic gene discovery in bread wheat

Abstract

A high level of genetic diversity was found in the A. E. Watkins bread wheat landrace collection. Genotypic information was used to determine the population structure and to develop germplasm resources. In the 1930s A. E. Watkins acquired landrace cultivars of bread wheat (Triticum aestivum L.) from official channels of the board of Trade in London, many of which originated from local markets in 32 countries. The geographic distribution of the 826 landrace cultivars of the current collection, here called the Watkins collection, covers many Asian and European countries and some from Africa. The cultivars were genotyped with 41 microsatellite markers in order to investigate the genetic diversity and population structure of the collection. A high level of genetic diversity was found, higher than in a collection of modern European winter bread wheat varieties from 1945 to 2000. Furthermore, although weak, the population structure of the Watkins collection reveals nine ancestral geographical groupings. An exchange of genetic material between ancestral groups before commercial wheat-breeding started would be a possible explanation for this. The increased knowledge regarding the diversity of the Watkins collection was used to develop resources for wheat research and breeding, one of them a core set, which captures the majority of the genetic diversity detected. The understanding of genetic diversity and population structure together with the availability of breeding resources should help to accelerate the detection of new alleles in the Watkins collection.

Fig. 1

Outlines of density functions created from phenotypic values for the following bread wheat collections or sets: Watkins 2006 (red, hashed); Gediflux 2011 (blue); Watkins core 2006 and 2011 (red, dotted and dot hashed, respectively); Watkins data fitted to 2011 conditions (orange). a Days to ear emergence [days after May 1st], b plant mature height [cm], c thousand grain weight [g], d grain length [cm], e grain surface area [cm²], f: grain width [cm]. Abbreviations: W Watkins, G Gediflux, 2006 and 2011 years collections were grown (colour figure online)

Fig. 2

a The world map. Countries from which LCs were acquired are coloured. Colours are organised in geographic regions. b STRUCTURE assignment of the Watkins LCs to ancestral populations. Three panels shown. Top panel whole collection; middle and lower panel the 424 and 630 subpopulations of the whole collection, respectively. Each panel is divided into three rows. Top row assignment to ancestral population; middle row ancestral characteristics of each line; bottom row colour code of country/region of origin. Abbreviated names of the LCs are given below the bottom row. c Colour code of the countries, according to geographic regions

Fig. 3

Representation of the STRUCTURE assignment of the Gediflux MCs into two ancestral populations. The panel is divided into four rows which show (from top to bottom): Row 1 assignment to ancestral population as detected by STRUCTURE (population 1: dark green, population 2: light green). Row 2 ancestral characteristics of each line as detected by STRUCTURE (colours as in row 1). Row 3 colour code of decade of release for varieties from the EU recommended list. Row 4 colour code of origin: EU recommended list (green) or UK national list (yellow). The accession numbers of the Gediflux varieties are given below row 4. Legends with colour code for the different rows are given below the plot (colour figure online)