MOLEKULĀRO MARĶIERU PIELIETOJUMA REZULTĀTI MILTRASAS IZTURĪGU VASARAS MIEŽU SELEKCIJAS LĪNIJU IZLASĒ.

The application of fungicide and genetic resistance of a variety are two key elements determining disease control options in spring barley (Hordeum vulgare L.). In Latvia the barley powdery mildew (Blumeria graminis f.sp. hordei) is an economically important pathogen, although there are also effective fungicides to limit the development of disease under conventional and integrated farming systems significantly raising the cost of the cultivation of barley. Natural resistance to powdery mildew is particularly important for organic farming. Only the Mlo locus in homozygous recessive status (mlo) provides broad spectrum resistance against almost all barley mildew isolates where mlo-9 is one of the most commonly used alleles in breeding. The aim of this study was to identify mlo-9 allele by molecular markers to select breeding lines resistant to powdery mildew. Forty-three F4 generation lines (24 hulless, 19 covered) were analyzed from the hybridization combination between hulless barley genotype PR3527 (Latvia) and covered barley variety 'Barke' (Germany), which is a mlo-9 allele donor. Seven hulless and 12 covered barley lines contained mlo-9 allele in homozygous recessive status where these lines also under field conditions showed complete resistance to powdery mildew. Overall, for 13 lines there was no mlo- 9 allele identified, but 9 lines were heterozygous confirming segregation of resistance to powdery mildew. As a result of this research, genetically resistant to powdery mildew breeding initial material was obtained confirming the perspective of molecular markers application in the breeding of barley varieties resistant to powdery mildew. [ABSTRACT FROM AUTHOR]