Leaf rust is the most widespread and frequently occurring fungal disease of wheat (
Triticum aestivum
L.) in Ukraine and
worldwide. The information about the effectiveness of
Lr-genes and also the consequent monitoring of virulence dynamics
is necessary for the successful wheat breeding for leaf rust resistance. In 2013-2014 pathotype composition and virulence
analysis was studied both on the standard differential set and on the North American System of Nomenclature. According
to the standard differential set, 12 phenotypes were identified, of which the most common were 77 (75%) and 144 (6%).
A total of 40 phenotypes were identified on the North American Nomenclature. Phenotypes TGTT (24%) and TJTT (8%)
were the most frequent, TRTT (1.5%) and TSTT (1.5%) were within the broadest spectrum of virulence among the isolates
found in the south of Ukraine. For virulence analysis we used wheat lines of ‘Thatcher’ that are near-isogenic for 24 leaf
rust resistance genes and additionally four cultivars/lines. No virulence to Lr19 was found, whereas increasing virulence to
Lr9 was detected (13%). Low frequency of virulence was observed to
Lr29 (11%) and
Lr47 (21%), high level of virulence
was detected to other genes. The effectiveness of 53 known
Lr-genes was studied at the seedling and the adult plant stages.
Most of them were not effective against leaf rust. Genes
Lr9,
Lr19,
Lr29, and
Lr47 were highly effective both at the seedling
stage and at adult plant stage. Genes
Lr24,
Lr42,
Lr50,
Lr51, and
Lr56 were effective only at the adult plant stage.
