A genotype–phenotype approach to discriminate Central European spelt landraces from modern wheat-spelt intercrosses in the Swiss context

Marketed as a healthier alternative to bread wheat, spelt (Triticum aestivum ssp. spelta) is in increasing demand from consumers and bakers in Switzerland. The Swiss spelt landscape is currently dominated by two varieties—Ostro and Oberkulmer Rotkorn—considered as references for Swiss “typical” spelt. However, these two varieties are rather old and deliver low yields; the market therefore needs improved spelt varieties with higher agronomic potential while keeping the essential attributes of typical spelt. As spelt and winter wheat can be interbred, modern spelt varieties often result from crosses between the two. It has therefore become increasingly difficult to distinguish between typical spelt and modern wheat-spelt intercrosses. This project aims to clarify the phenotypic distinction between typical spelt and modern wheat-spelt intercrosses in the Swiss context. To do this, we performed field trials with 50 spelt varieties, including typical and modern cultivars from Switzerland and Central Europe. We measured agronomic, rheological and nutritional parameters of each variety. In addition, these cultivars were genotyped using a 25 K Illumina Wheat SNP array. This allowed us to identify which phenotypic parameters were associated with genetic proximity to typical spelt. Swiss typical spelt varieties were characterized by highly extensible doughs, later phenology, low harvest index, high thousand kernel weights, and lower Zeleny/protein ratio. By linking phenotypic characteristics, easily measurable in fields, to the underlying genetic information of each variety, these results will help to better classify spelt varieties in Switzerland and pave the way for more clarity and transparency on the Swiss spelt market.