Effectiveness of known wheat resistance genes Triticum aestivum L. to Puccinia triticina Eriks. leaf rust of wheat in 2019–2020

The wheat leaf rust is widespread throughout Ukraine, which makes it necessary to monitor the effectiveness of host plant resistance genes. In 2019–2020, under the conditions of the subpopulation of the pathogen, typical for the Right Bank Forest-Steppe zone of Ukraine, the effectiveness of known resistance genes was determined. Evaluation was conducted after the 2018 epiphytotypic series on a series of nearly isogenic Thatcher wheat lines and cultivars that expand the core gene set. According to the research results, they are distributed into several groups according to the level of expression: 1) genes capable of determining a very high level of resistance to all local races of the pathogen (score 9 – no signs of the disease; score 8 – single necrotic spots) Lr9, Lr18, Lr19, Lr21, Lr25, Lr27+31, Lr28, Lr35, Lr41, Lr43+24, Lr50, LrTm; 2) genes determining resistance – plants are slightly affected by the pathogen (score 8 – single necrotic spots and urediniopustules with an intensity of up to 5 %; score 7 – urediniopustules with an intensity of up to 10 %; score 6 – small and medium urediniopustules with an intensity of up to 15 %) – Lr22a, Lr32, Lr34, Lr42, Lr43, Lr46; 3) resistance genes whose expression level is defined as labile (heterogeneous) – Lr2a, Lr2b, Lr12, Lr14a, Lr14b, Lr20, Lr23, Lr24, Lr39, Lr40. The last group is characterized by variability and depends on the level of infectious load and virulence of the pathogen population as a whole. We recommend using the listed resistance genes in the selection process, taking into account the characteristics of the last group. The genes Lr1, Lr2c, Lr3, Lr3ka, Lr3bg, Lr10, Lr11, Lr13, Lr15, Lr16, Lr17, Lr26, Lr29, Lr30, Lr33, Lr37, LrB are ineffective against all races of the leaf rust pathogen population in the Right Bank Forest Steppe zone of Ukraine. If they are associated with useful traits, their use in selection should be carried out at the expense of pyramiding with other more effective resistance genes.