High density mapping and haplotype analysis of the major stem-solidness locus SSt1 in durum and common wheat.

Kirby T Nilsen,Curtis J Pozniak,P R Maclachlan,Amidou N’Diaye,Ron E Knox,Sean Walkowiak,Krystalee Wiebe,Richard D Cuthbert,John M Clarke,Aron T Cory,Assaf Distelfeld,Yuefeng Ruan,Fran R Clarke,Brian L Beres,Andrew G Sharpe,Robert J Graf,Aimin Zhang

doi:10.1371/journal.pone.0175285

Abstract

Breeding for solid-stemmed durum (Triticum turgidum L. var durum) and common wheat (Triticum aestivum L.) cultivars is one strategy to minimize yield losses caused by the wheat stem sawfly (Cephus cinctus Norton). Major stem-solidness QTL have been localized to the long arm of chromosome 3B in both wheat species, but it is unclear if these QTL span a common genetic interval. In this study, we have improved the resolution of the QTL on chromosome 3B in a durum (Kofa/W9262-260D3) and common wheat (Lillian/Vesper) mapping population. Coincident QTL (LOD = 94–127, R2 = 78–92%) were localized near the telomere of chromosome 3BL in both mapping populations, which we designate SSt1. We further examined the SSt1 interval by using available consensus maps for durum and common wheat and compared genetic to physical intervals by anchoring markers to the current version of the wild emmer wheat (WEW) reference sequence. These results suggest that the SSt1 interval spans a physical distance of 1.6 Mb in WEW (positions 833.4–835.0 Mb). In addition, minor QTL were identified on chromosomes 2A, 2D, 4A, and 5A that were found to synergistically enhance expression of SSt1 to increase stem-solidness. These results suggest that developing new wheat cultivars with improved stem-solidness is possible by combining SSt1 with favorable alleles at minor loci within both wheat species.

Highlights

The wheat stem sawfly (WSS) (Cephus cinctus Norton) is a destructive insect pest of durum (Triticum turgidum L var durum) and common wheat (Triticum aestivum L.) in the northern Great Plains of North America
Pith expression differences exist between durum and common wheat The pattern of phenotypic variation differed for stem-solidness between the two doubled haploid (DH) mapping populations
The distribution of the stem-solidness phenotype in the Kofa/W9262-260D3 DH population was bimodal with scores ranging from one to five (p < 0.05), with two clear and distinct groups clustering near the extremes of the stem-solidness rating scale (Fig 1A)

Summary

Introduction

The wheat stem sawfly (WSS) (Cephus cinctus Norton) is a destructive insect pest of durum (Triticum turgidum L var durum) and common wheat (Triticum aestivum L.) in the northern Great Plains of North America. In Canada, severe infestations of WSS have been reported in southern Alberta, Saskatchewan and eastern Manitoba since the early 1920s [1]. Mapping and haplotype analysis of stem-solidness locus SSt1 in wheat and the Saskatchewan and Alberta Wheat Development Commissions. The financial support provided through the AgriFlex Program of Agriculture and Agri-Food Canada is acknowledged. Knowles scholarship administered by the University of Saskatchewan

Methods

Results

Discussion

Conclusion