High-density genotyping of the A.E. Watkins Collection of hexaploid landraces identifies a large molecular diversity compared to elite bread wheat.

Mark O Winfield,Alexandra M Allen,Christy Waterfall,Paul A Wilkinson,Luzie U Wingen,Simon Griffiths,Keith J Edwards,Gary L.A Barker,Amanda J Burridge,Jane Coghill

doi:10.1111/pbi.12757

Mark O Winfield, Alexandra M Allen + Show 8 more

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https://doi.org/10.1111/pbi.12757

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Abstract

SummaryThe importance of wheat as a food crop makes it a major target for agricultural improvements. As one of the most widely grown cereal grains, together with maize and rice, wheat is the leading provider of calories in the global diet, constituting 29% of global cereal production in 2015. In the last few decades, however, yields have plateaued, suggesting that the green revolution, at least for wheat, might have run its course and that new sources of genetic variation are urgently required. The overall aim of our work was to identify novel variation that may then be used to enable the breeding process. As landraces are a potential source of such diversity, here we have characterized the A.E. Watkins Collection alongside a collection of elite accessions using two complementary high‐density and high‐throughput genotyping platforms. While our results show the importance of using the appropriate SNP collection to compare diverse accessions, they also show that the Watkins Collection contains a substantial amount of novel genetic diversity which has either not been captured in current breeding programmes or which has been lost through previous selection pressures. As a consequence of our analysis, we have identified a number of accessions which carry an array of novel alleles along with a number of interesting chromosome rearrangements which confirm the variable nature of the wheat genome.

Highlights

Bread wheat (Triticum aestivum), with production of more than 730 million tonnes in 2015 constituting 29% of global cereal production, is the main provider of calories in the diet globally (FAO Cereal Supply and Demand Brief)
While global demand for wheat is increasing by 1.7% each year due to population growth and increase in average incomes (Lobell et al, 2009), wheat yields have plateaued over the last 10–15 years (Grassini et al, 2013); with a projected decline in wheat productivity over the coming years of between 6 and 8% due to climate change (Schleussner et al, 2016), it seems that wheat production is not on track to meet demand
One of the main aims of this study was to use these new markers and platforms to see whether similar conclusions would be drawn with regard to the Watkins Collection of hexaploid lines and, in addition, identify novel markers that might be unique to this Collection and, not found in elite accessions

Summary

Introduction

Bread wheat (Triticum aestivum), with production of more than 730 million tonnes in 2015 constituting 29% of global cereal production, is the main provider of calories in the diet globally (FAO Cereal Supply and Demand Brief). It is suggested that, during the ‘Green Revolution’, breeding programmes were based on a small number of target genes (e.g. Rht dwarfing genes in wheat) such that elite lines experienced a bottle neck that reduced genetic diversity (Doebley et al, 2006; Khush, 2001; Roussel et al, 2005). This might not generally be the case, since breeding programmes in different countries and at different times have produced variable results with respect to preserving underlying levels of genetic diversity (van de Wouw et al, 2009). Novel sources of genetic variability are required to allow breeders to face the challenge of increasing wheat yields in an insecure future

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