Hereditary and molecular validity of pleiotropic resistance to rusts and powdery mildew in hexaploid wheat

To study the genetic basis of pleiotropic resistance to rusts and powdery mildew in hexaploid wheat, three Egyptian cultivars, Misr-1, Sids-13 and Sakha-94 were crossed to three CIMMYT cultivars carrying pleiotropic resistance genes i.e., Pavon-76 (Sr2/Yr30/Lr27, Lr46/Yr29/Sr58/Pm39), Jupateco-73-R (Lr34/Yr18/Sr57/Pm38) and Seri-82 (Lr26/Sr31/Yr9). In F-2 progeny test, no segregation was found in four crosses, Pavon-76/Misr-1, Pavon-76/Sids-13, Jupateco-73-R/Sids-13, and Jupateco-73-R/Sakha-94, indicating the dominance of pleiotropic adult plant resistance (PAPR). Segregation ratios of the other five crosses fitted the expected ratios indicating the absence of these genes in the tested Egyptian cultivars. There was a difference between each of the two parents that was controlled by digenic recessive or dominance. Molecular screening revealed that three PAPR genes Sr2/Yr30/Lr27, Lr46/Yr29/Sr58/Pm39 and Lr34/Yr18/Sr57/Pm38 were present in the majority of resistant F-2 plants, while, race-specific gene Lr26/Sr31/Yr9 was present mostly in susceptible F-2 plants. PAPR genes should be considered for marker-assisted wheat breeding.