8th INTERNATIONAL WHEAT CONFERENCE

175 isolates were identified for virulence determining using the set of differential Thatcher
near-isogenic lines with 40 resistance genes. As result of the conducted tests high virulence
of Puccinia triticina population was revealed. Virulence to thirty one lines was
recorded. All analyses isolates were virulent to Lr2c, 3, 3ka, 10, 11, 14a, 14b, 16, 17, 22a,
22b, 30, 32, 33, 34, 37, B. Virulence frequencies to genes Lr3bg, Lr21, Lr23, Lr25, Lr26,
Lr35, Lr36 were 72.9-98.5% of isolates across the country. Low virulence (0.8-8.2%) was
recorded to genes Lr2a, Lr2b, Lr15, Lr20. Virulence to lines with genes Lr1, Lr2b, Lr27,
Lr31 and Lr18 occurred in 23.3%, 13.5%, 26.3% and 43.6% of the isolates, respectively.
No virulence was found to Lr9, Lr19, Lr24, Lr28, Lr29, Lr23+10. These genes provide
protection against leaf rust during many years in Georgia and other countries. Forty nine
pathotypes were described in Puccinia triticina population. The most common pathotype
2c, 3, 3ka, 3bg, 10, 11, 14a, 14b, 16, 17, 18, 21, 22a, 22b, 23, 25, 26, 30, 32, 33, 34, 35, 36, 37,
B were occurred in 17.0% of the isolates. Dominant pathotypes consist of 23-25 virulence
genes. According to American Nomenclature System common pathotypes are following:
FHTSL, FHTTL, and PHTTL.
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