Triticale is derived from a cross between wheat and rye and the leaf rust pathogen of wheat, Puccinia triticina (Pt), and that of rye, P. recondita sensu stricto (Pr), can potentially cause disease in this crop. Recent studies showed that wheat rust fungi could adapt to warmer temperatures. In this paper, we report on the comparative virulence of three Pt races and one Pr isolate (all were collected in South Africa) on triticale as well as their in vitro response to temperature. Seedling infection types (SITs) of 169 triticale entries to Pt races 3SA144 (North American code SDDN), 3SA145 (CCPS) and 3SA248 (CFPS) and Pr isolate UVPr2 revealed that 3SA144 is the most virulent with 106 triticale entries found susceptible to this race. The three Pt races were avirulent to the four rye cultivars included as controls. UVPr2 was avirulent on all the triticale entries and 49 entries were considered resistant to the Pt races tested. Freshly harvested urediniospores of the above isolates were tested at constant temperature regimes of 10 °C, 22.5 °C and 35 °C to study germination characteristics. Mean urediniospore germination percentages as determined for 3SA144 (61.3%) and UVPr2 (62.6%) were significantly lower when compared to 3SA145 (83.7%) and 3SA248 (84.9%). Race 3SA144 was most sensitive to the higher temperature regime of 35 °C (5.2% germination). Among the investigated races, 3SA144 showed significantly lower mean germ tube elongation rates at all three incubation temperatures. This is the first report of differences in temperature adaptation between Pt races from SA.
Isolates of Puccinia triticina were
obtained from wheat and triticale nurseries and fields in Hungary. Pathotypes
were determined on 15 Thatcher wheat lines that are near-isogenic for leaf rust
resistance. Thirteen pathotypes were identified from 70 Puccinia triticina
isolates collected from infected wheat plants, and 2 pathotypes were identified
from 12 Puccinia triticina isolates obtained from infected triticale leaves.
Most pathotypes identified in Hungary were virulent to resistance genes Lr2b,
Lr2c, Lr3, Lr11, Lr17, Lr21, Lr26, but pathotypes from triticale were virulent
only to Lr2b, Lr2c and Lr11. Among the examined 15 Lr genes Lr2a, Lr9, Lr19,
Lr23, Lr24 and Lr28 were highly effective. The most common pathotypes were
43522, 43722 and 53522 on wheat plants, among them 53522 was new in rust
populations. Pathotypes 41000 and 41100 obtained from infected triticale plants
were identified for the first time in the Hungarian Puccinia triticina
populations. The number of pathotypes with virulence to Lr1, Lr2b and Lr21
increased from 1999 to 2004. Virulence to other Lr genes declined, because a
lot of susceptible cultivars were removed from production during the past five
years. In 2004, most predominant cultivars grown in Hungary were resistant or
moderately resistant to leaf rust.
The present study was conducted to determine the reactions of 88 bread wheat pure lines selected from landraces collected in Central Anatolian Region of Turkey against leaf rust (Puccinia triticina) under field conditions in 7 locations. GGE biplot analysis was used to determine the reactions of landrace genotypes against the disease. The GGE biplot explained 73.89% of total variation. Among the experimental locations, 6 (except for E3) were placed close to each other over the biplot graph, indicating two apparent mega-environments. The GGE biplot visually displayed the resistance and stability of the pure lines to leaf rust. The landrace genotypes L18, L19, L45, and L2 were identified as the most resistant/stable genotypes in all environments and L31 and L56 were the most susceptible/stable genotypes.