Inheritance of resistance to loose smut [Ustilago tritici] in three durum wheat lines

Abstract

This study was conducted to determine the mode of inheritance of resistance to loose smut [Ustilago tritici] in the resistant durum wheat (Triticum turgidum) lines Orgaz, Tripolitico, and VIR53877 to identify a simply inherited resistance factor effective against multiple races of the pathogen. The resistant durum wheat lines were crossed with a susceptible durum wheat cultivar, ‘Sceptre’, to produce F₁, F₂, and F₃ generations. Plants of each generation were inoculated with races T26, T32, and T33 of U. tritici. The F₁ plants from crosses Orgaz/Sceptre, Tripolitico/Sceptre, and VIR53877/Sceptre exhibited no smut, indicating dominant-gene expression. Segregation of resistance among the F₂ and F₃ progenies of the cross Orgaz/Sceptre fitted a one-gene ratio when tested with race T26 and a two-gene ratio to each of races T32 and T33. The genes controlling resistance to the races appeared to be independently inherited. In the cross Tripolitico/Sceptre, one gene controlled resistance to race T26, and two genes controlled resistance to each of races T32 and T33. These genes were not independently inherited. One gene conferring resistance to race T26, and two genes conferring resistance to each of T32 and T33, were also observed in the cross VIR53877/Sceptre. There appeared to be a common gene for resistance to both T32 and T33. Tripolitico appears to hold the greatest promise of providing broad resistance to U. tritici with simple inheritance.

Keywords:

• durum wheat
• Triticum turgidum
• inheritance
• resistance
• Ustilago tritici
• loose smut