GENETICS OF STEM RUST RESISTANCE IN THE DURUM-WHEAT ACCESSION REICHENBACHII

Inheritance of seedling reactions to cultures of races TLM and MBCT of Puccinia graminis f.sp. tritici was studied in crosses of the resistant durum 'Reichenbachii' with susceptible 'Marruecos 9623' and 'DZ04-118'. The Chi-square test for goodness of fit was used to analyze segregating populations. Two independent recessive genes appeared to control resistance of Reichenbachii to both TLM and MBCT. Depending upon the cross, the two genes interacted cumulatively to condition immunity or higher levels of resistance than either parent conditioned singly. There was no evidence of maternal influence on the inheritance of resistance. Resistance genes in Reichenbachii were recessive; therefore, breeders should consider the use of relatively large F2 populations to effectively transfer these genes to cultivars with good agronomic characteristics.