The wheat Phs-A1 pre-harvest sprouting resistance locus delays the rate of seed dormancy loss and maps 0.3 cM distal to the PM19 genes in UK germplasm.

Oluwaseyi Shorinola,James Simmonds,Miroslav Valárik,Cristobal Uauy,M J Holdsworth,Nicholas Bird,Peter Jack,Tina Henriksson,Simon Berry,Tanja Gerjets,John Flintham,Barbara Balcárková,Duncan Scholefield,Peter Werner

doi:10.1093/jxb/erw194

Abstract

The precocious germination of cereal grains before harvest, also known as pre-harvest sprouting, is an important source of yield and quality loss in cereal production. Pre-harvest sprouting is a complex grain defect and is becoming an increasing challenge due to changing climate patterns. Resistance to sprouting is multi-genic, although a significant proportion of the sprouting variation in modern wheat cultivars is controlled by a few major quantitative trait loci, including Phs-A1 in chromosome arm 4AL. Despite its importance, little is known about the physiological basis and the gene(s) underlying this important locus. In this study, we characterized Phs-A1 and show that it confers resistance to sprouting damage by affecting the rate of dormancy loss during dry seed after-ripening. We show Phs-A1 to be effective even when seeds develop at low temperature (13 °C). Comparative analysis of syntenic Phs-A1 intervals in wheat and Brachypodium uncovered ten orthologous genes, including the Plasma Membrane 19 genes (PM19-A1 and PM19-A2) previously proposed as the main candidates for this locus. However, high-resolution fine-mapping in two bi-parental UK mapping populations delimited Phs-A1 to an interval 0.3 cM distal to the PM19 genes. This study suggests the possibility that more than one causal gene underlies this major pre-harvest sprouting locus. The information and resources reported in this study will help test this hypothesis across a wider set of germplasm and will be of importance for breeding more sprouting resilient wheat varieties.

Highlights

Pre- and post-harvest crop losses caused by biotic or abiotic security
Alchemy × Robigus fine-mapping population For subsequent characterization and fine mapping of Phs-A1 in the Alchemy × Robigus population, we developed near isogenic lines (NILs) and recombinant inbred lines (RILs)
The 4AL quantitative trait loci (QTL) effect is known to segregate in UK wheat varieties (Flintham et al, 2011) and has been identified in doubled haploid (DH) populations derived from crosses between Alchemy × Robigus and Option × Claire (Alchemy and Option providing the resistance allele)

Summary

Introduction

Pre- and post-harvest crop losses caused by biotic or abiotic security. In addition to their detrimental effects on crop yield, stress factors are major drawbacks to attaining global food their effects on quality are damaging. Sprouting (PHS) represents one such source of both yield and quality loss in global wheat production. PHS is characterized by the precocious germination of grains before harvest with consequent reductions in seed viability and end-use value, for bread-making purposes. Adverse environmental conditions like heat stress or water deficit during grain development have been generally associated with higher levels of seed germination upon grain maturation and this predisposes plants to incidences of PHS (Rodriguez et al, 2011). Given the current climate change projections of increased temperature and precipitation in parts of the world (Walther et al, 2002; Trenberth, 2011), the incidence of PHS is expected to increase and become a greater challenge in wheat production areas

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Conclusion