Archivio Journal of Plant Pathology

Abstract:

A total of 44 accessions of barley landraces from Morocco were screened for resistance to powdery mildew. Nineteen of the tested landraces showed resistance reactions and 45 lines were selected. Sixteen of these lines were tested at the seedling stage with 17, and another 29 lines with 23 differential isolates of powdery mildew respectively. Six lines (170-1-3, 172-3-2, 173-1- 2, 181-3-5, 201-3-2, 201-3-3) were identified that have resistance to all the prevalent European powdery mildew virulence genes. It was postulated that 3 different resistance alleles (Mlat, Mla6, and Mla14) are present in the tested lines either alone or in combination. Among the tested lines 8 (18.0%) had one specific gene for resistance and 37 (82.0%) had a combination of different genes for resistance. Among specific resistance alleles the most common was Mlat whose presence was postulated in 20 (44.4%) of the tested lines. The distribution of reaction type indicated that about 79.0% of all reaction types observed were classified as powdery mildew resistance (scores 0, 1 and 2). The majority (65.0%) of resistance reaction types observed in the tested lines was intermediate reaction type 2. The use of new effective sources of resistance from Moroccan barley landraces for diversification of resistance genes for powdery mildew in barley cultivars is discussed.