Virulence of yellow rust races and types of resistance in wheat cultivars in Kenya
1991
Danial, D.L. (Agricultural University, Wageningen (Netherlands). Plant Breeding Departament (IVP)) | Stubbs, R.W. (Research Institute for Plant Protection (IPO), Wageningen (Netherlands))
Virulence analyses of yellow rust isolates were carried out in Kenya between 1986-1989, and were compared with earlier results. Races showed a clear increase in the number of virulence factors. Before 1980, 0 to 7 virulence factors were detected whereas the dominant races after 1980 were characterized by 7 to 12 virulence factors. Virulence was detected for the resistance genes Yr2, Yr2+, Yr6, Yr6+, Yr7, Yr7+, Yr8, Yr9, Yr9+, and on the cultivars Anza (A), Strubes DicKkopf and Suwon92/ Omar, while virulences for Yr3(V) Vilmorin23, Yr4+, Yr5, Carstens V and Spaldings Prolific were not found. In the past ten years, the resistance of at least six cultivars, Paa, K.Popo, K.Kulungu, K.Kima K.Tumbili and Pasa broke down. They were shown to carry race-specific major resistance genes such as Yr2, Yr6, Yr7, Yr9 and A. However, in the field, the resistance of these cultivars was not completely neutralized. A residual resistance, possibly controlled by minor genes, appeared to be present. Other wheat cultivars such as Africa Mayo, K.Kudu, K4500 (=Enjoy), K.Leopard, Bounty, Frontatch, Trophy, Bonny and K.Plume appeared to retain their resistance over a considerable time period, and are considered to be durably resistant to the Kenyan yellow rust populations. This form of resistance can be recommended for use in breeding programs
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