Powdery mildew resistance in selections from moroccan barley landraces

Thirty barley landraces collected from Morocco in 1985 and 1989, and held in the Polish Gene Bank, IHAR, Radzików, Poland, were screened for resistance to powdery mildew. Fifteen tested landraces (50%) showed powdery mildew resistance reactions and 24 single plant lines were selected. Eighteen lines originating from 13 landraces were tested with 17 isolates of powdery mildew and another six lines originating from six landraces were tested with 23; the isolates were chosen according to their virulence spectra observed on the ‘Pallas’ isolines differential set. Three lines (E 1090-2-2, E 1110-3-2 and E 1077-1-1) showed resistance to all powdery mildew virulence genes prevalent in Europe. In 21 lines, unknown genes alone or in combination with specific ones were detected. Five different resistance alleles(Mlat, Mlal, Mla3, Mlg andMl(CP)) were postulated to be present in the tested lines, alone or in combination:Mlat was postulated to be present in nine (~38%) lines;Mlg andMl(CP) in two lines, andMla1 andMla3 in one tested line each. The use of newly identified sources of resistance in barley breeding as a means of controlling powdery mildew is discussed.