use of microsatellite markers to determine the relative proportions of grain produced by cultivars and the frequency of hybridization in bread wheat mixtures

Two polymorphic microsatellite markers were selected to identify 24 bread wheat cultivars commonly grown in France and to estimate the proportions of cultivar and hybrid grains in the harvests of four 4‐cultivar mixtures (CM 1‐4) planted in equal proportions in farmers’ fields. This technology was used not only to determine whether a mixture comprises the declared cultivars, but also whether there is any contamination with other cultivars, to identify the contaminants and to estimate their proportions. At harvest, the cultivar proportions ranged from 15 to 37%. Only in the mixture CM2 (‘Malacca’, ‘Somme’, ‘Renan’ and ‘Soissons’), did the cultivars contribute equally to the harvest. The other cultivar mixtures CM1 (‘Malacca’, ‘Somme’, ‘Renan’ and ‘Camp Remy’), CM3 (‘Malacca’, ‘Texel’, ‘Apache’ and ‘Aligre’) and CM4 (‘Malacca’, ‘Somme’, ‘Apache’ and ‘Virtuose’) showed significantly unequal cultivar proportions with ‘Somme’ dominating ‘Renan’ and ‘Camp Remy’ in CM1, and ‘Apache’ dominating ‘Malacca’ and ‘Aligre’ in CM3 and ‘Malacca’ in CM4. Similar cultivar proportions were measured with gliadin and glutenin markers in the mixtures CM3 and CM4, confirming the results with microsatellites. No contamination was found. Hybrids accounted for between 1.3 and 6.3% of the grains produced in the four cultivar mixtures.