Development of new bread wheat resistant mutants for Ug99 rust disease (Puccinia graminis f. sp. tritici).

Abstract

Abstract M3 derived mutants from two bread wheat varieties, namely, 'Giza 186' and 'Saha 93', were screened for resistance to the rust Ug99 at two locations in Njoro (Kenya) and in Tihama (Yemen). At Tihama, two mutants of 'Giza 186' (G-M2-2010-1-28 and G-M2-2010-41-52) and four mutants of 'Saha 93' (S-M2-2010-16-12, S-M2-2010-21-13, S-M2-2010-22-14 and S-M2-2010-27-15) were seen to be resistant at both seedling and adult stages while their parents were resistant at seedling stage and susceptible at adult stage. In Kenya, the resistance score of the mutants was slightly different from those obtained at Tihama. The mutants G-M2-2010-1-28 and G-M2-2010-41-52 were stable in their level of resistance recorded at Tihama, but only two mutants of 'Saha 93' (S-M2-2010-16-12 and S-M2-2010-27-15) were resistant at both growth stages. S-M2-2010-22-14 and S-M2-2010-21-13 were resistant at the seedling stage while susceptible at adult stage. Further selection on these mutants for yield potential, agronomic performance and yellow rust disease resistance, as well as on selected mutants of both 'Giza 186' and 'Saha 93', at M5-M6 stages identified superior mutant lines compared with the two parents 'Saha 93' and 'Giza 186'. These included the line Erra-010-GM2w-41-52-40, which ranked first in yield (3768 kg/ha), followed by the lines Erra-010-SwM2-16-12-19, Erra-010-GM2w-1-28-18 and Erra-010-SwM2-22-14-6. Moreover, it can be concluded that Erra-010-GM2w-41-52-40 and Erra-010-SwM2-16-12-19 are highly recommended for their resistance to stem and yellow rust diseases as well as for yield potential and preference by farmers. Therefore, efforts are in progress to increase their seeds for dissemination over a wide range of farmers and wheat areas where rust diseases are an epidemic, and for registration of the lines as improved mutant varieties.