Meeting the Challenge of Yellow Rust in Cereal Crops - ICARDA

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Umanka. The same disease reaction was observed when genotypes were tested
with races Pst-43 and Pst-37. Race Pst-17 was virulent on most of genotypes
studied, except for Ulugbek 600 and Sharora, on which a resistant reaction was
detected. Thus, the more harmful North American races of P. s. f.sp. tritici for
germplasm from Central Asia are represented by Pst-17 and Pst-100.
According to Chen (2005), race Pst-100 is virulent on North American
differentials Lemhi (Yr21), Heines VII (Yr2, Yr25, YrHVII), Produra (YrPr1,
Pr2), Yamhill (Yr2, Yr4a, YrYam), Stephens (Yr3a, YrS, YrSte), Lee (Yr7, Yr22,
Yr23), Fielder (Yr6, Yr20), Express, (Yr8, Yr9), Clement (Yr9, Yr25, YrCle) and
Compare (Yr18, Yr19).
Based on seedling tests, cultivars Taza, Krasnovodopadskaya 25 and
Ulugbek 600 have all-stage resistance (also called seedling resistance).
Based on field tests, entries from a Trap Nursery (CWAYRTN) were
screened for P.s. f.sp. tritici to assess the effectiveness of known resistance
genes, resistant commercial cultivars and advanced lines. Analysis of the trap
nursery at three locations in Central Asia is shown in Table 2. In conditions of
Almaty oblast (NPCZR) and Zhambyl oblast (Otar) the reactions of
differentials and isogenic lines were approximately the same. However, in
Kyrgyzstan, reactions of these entries were different.
The most effective against P. striiformis in the region were the sources of
genes Yr2+, Yr4+, Yr5, Yr10 and Yr15, which demonstrated R-MR infection
type. The carriers of Yr1 were susceptible: 60-80S on Chinese 166 and 30-80S on
the isogenic line Yr1/6*Avocet S. Heines VII demonstrated a high level of
resistance (IT 0), but cultivars Kalyansona and Sonalika, which have Yr2, were
not resistant. The same reaction was observed on carriers of Yr3: cultivar
Vilmorin 23 (Yr3a, YrV23) was resistant, but cultivar Nord Desprez (Yr3a,
YrND) was susceptible. Hybrid 46 (Yr4b, YrH46) was moderately resistant
(10MR) in 2005. However, in previous years this cultivar was highly resistant
to yellow rust. A high level of resistance (0) in many locations was consistently
observed for Yr5 both in the original source of this gene (Triticum spelta var.
album) and in the isogenic line Yr5/6*Avocet S. Cultivar Heines Peko (Yr6,
YrHP) had a variable reaction, from MS-S (10S-30MS-90S) to highly resistant
(R), while the isogenic line Yr6/6*Avocet S was susceptible (60-80S).
Cranbrook (Yr7) and Lee (Yr7, Yr22, Yr23) demonstrated susceptible reactions
(20-30S). However, Corella (Yr6+Yr7) and Reichenberg 42 (Yr7) were resistant.