Candidate Genes Underlying QTL for Powdery Mildew Resistance in Triticale (x Triticosecale Wittm.)

Combining to tolerance to biotic and abiotic stresses is important target for modern triticale breeding. Cultivation of varieties resistant to fungal pathogens is economically and environmentally important and may lead to reducing of the use of fungicides. Molecular markers are necessary for accumulation of advantageous alleles in the best genotypes by means of marker-assisted and genomic selection approaches. In present research, QTL regions associated with the powdery mildew resistance at adult plant stage were evaluated in order to provide the effective selection tools. Testing of DH population in multiple environments under natural infestation revealed 20 QTL on wheat (4A, 3B, 4B) and rye (2R, 4R, 5R, 6R) chromosomes. Regions explained 8.1% - 29.3% of phenotypic variation depending of the trait, localization and year of the experiment. Main QTL with effect exceeding 15% were found on chromosomes 3B, 4B, 2R, 5R and 6R. QTL and candidate genes located on chromosomes 4B, 2R, 5R and 6R are so far reported for the first time as regions associated with PM resistance in the adult triticale plants. Additionally, within all QTL, 21 candidate genes associated with the PM resistance were revealed. Predicted function of protein encoded by these genes include triggering a defense system which restricts the pathogen growth, enzyme activity, regulation of hormone-activated pathways, transcriptional corepressor complex and cell wall construction. Availability of QTL, molecular markers together with candidate genes linked with the powdery mildew resistance can be validated on triticale lines and varieties and then, used in MAS to improve modern breeding.