Shorinola, O., Bird, N., Simmonds, J., Berry, S., Henriksson, T., Jack, P., Werner, P., Gerjets, T., Scholefield, D., Balcárková, B., Valárik, M., Holdsworth, M.J., Flintham, J. Uauy, C.
JOURNAL OF EXPERIMENTAL BOTANY 67: 4169-4178, 2016

Keywords: After-ripening, dormancy, PM19, pre-harvest sprouting, seed, synteny, Triticum aestivum
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.
DOI: 10.1093/jxb/erw194
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IEB authors: Miroslav Valárik