INHERITANCE OF RESISTANCE TO POWDERY MILDEW (ERYSIPHE-GRAMINIS F SP HORDEI) IN 11 PRIMITIVE BARLEY VARIETIES

The inheritance of the powdery mildew resistance of eleven primitive barley varieties was investigated. Crosses with varieties with identified resistance genes revealed that at least three different genes are present in a group of six genotypes from Greece ('Hor736', 'Hor847', 'Hor878', 'Hor1159', 'Hor1379' and 'Hor1873') and one from Turkey ('Hor1188'). One dominant gene is common to these seve genotypes and in the Greek accessions a second gene is present. The expression of this second gene was respectively dominant in the crosses with 'Hor736' and 'Hor1159', recessive in the crosses with 'Hor878' and 'Hor1873', and depended on the employed powdery mildew isolate in the crosses with 'Hor847' and 'Hor1379'. The detected genes differ from the resistance genes of the crossing partners, viz. Ml-al2, Ml-(Ab), Ml-(CP) and Ml-(1402). The accessions from China ('Hor824' and 'Hor4021') each possess two resistance genes which differ from Ml-al2, Ml-(La) and Ml-(CP). The major gene is common to both accessions and is either identical, allelic or closely linked to a gene in the variety 'Nigrate'. The Columbian accession 'Hor1894' possesses one resistance gene linked to a resistance gene in 'Nigrate' but this gene differs from the Ml-a locus. The variety 'Palestine' (Hor3997) possesses two resistance genes of which one is allelic or closely linked to Ml-(at).