Occurrence of tan spot (Pyrenophora tritici-repentis) in 2021/2022 growing season

Pyrenophora tritici-repentis (Died.) Drechs, prouzrokovač žutomrke pegavosti lista pšenice, je ekonomski značajno oboljenje koje dovodi do smanjenja mase i kvaliteta zrna kao i gubitaka prinosa do 53%. Ptr je nekrotrofni patogen i produkuje tri vrste nekrotrofnih efektora (NE) (Ptr ToxA, Ptr ToxB i Ptr ToxC) odgovornih za ostvarenje infekcije. Genetička osnova interakcije Ptr-domaćin uključuje i gene koji obezbeđuju rasno-nespecifi čnu otpornost. U 2022. godini, procentualna zastupljenost genotipova zaraženih sa Ptr u kolekcijama “rasadnika bolesti” kretala se od 11,4% do 94,3%. Najmanji broj zaraženih genotipova (11,4%) zabeležen je u programima oplemenjivanja na otpornost prema prevalentim patogenima. Nizak broj zaraženih genotipova sa Ptr utvrđen je i u kolekciji divljih srodnika (18,4%) dok je najveća procentualna zastupljenost genotipova osetljivih na Ptr utvrđen kod linija i sorti poreklom iz Kazahstana (94,4%). Intenziteti zaraze pšenice kretali su se od traga do indeksa oboljenja preko 50 %. Dužina konidija Ptr kretala se od 73,4μm do 107,2 μm. Širina konidija obuhvatala je opseg od 15,5 do 22,8 μm. Rezultati ovih ispitivanja mogu biti osnova ne samo za odabir genotipova, nosioca izvora otpornosti, već i kao baza za dalja ispitivanja mehanizama koji obezbeđuju otpornost prema Ptr.Pyrenophora tritici-repentis (Died.) Drechs, the agent of tan spot, is an economically important pathogen of wheat. It causes grain quality distortion and yield losses up to 53%. Ptr is a necrotrophic pathogen and produces three types of necrotrophic eff ectors (NEs) (Ptr ToxA, Ptr ToxB and Ptr ToxC) that induce necrosis and chlorosis. The genetic basis of the Ptr-host interaction also includes genes that provide race-nonspecific resistance. In 2022, the percentage of genotypes infected with Ptr in the collections of “disease nurseries” ranged from 11.4% to 94.3%. The lowest number of infected genotypes (11.4%) was recorded in breeding programs for resistance to prevalent pathogens. A low number of genotypes infected with Ptr was also found in the collection of wild relatives (18.4%), while the highest percentage of genotypes susceptible to Ptr was found in varieties originating from Kazakhstan (94.4%). Disease index of Ptr ranged from a trace level up to 50% or more. The length of the Ptr conidia ranged from 73.4 μm to 107.2 μm. Conidia width ranged from 15.5 to 22.8 μm. The results of this study indicated on genotypes that could be used as sources of resistance to Ptr, and also could be introduce in further studies of the mechanisms that provide resistance for Ptr