Tan spot and its causal agent Pyrenophora tritici-repentis
2022
KanepsKaņeps, Jānis, Janis | Bankina, Biruta | Morocko-BicevskaMoročko-Bičevska, Inga, Inga | SvartaŠvarta, Agrita, Agrita | Roga, Ance | FridmanisFridmanis, Dāvids, Davids
Wheat (Triticum spp.) is one of the important and widely grown crops in Latvia and across the globe. Wheat diseases are significant risk factors in wheat production systems, and farmers need knowledge about relevant plant disease control. Tan spot caused by Pyrenophora tritici-repentis is the most severe wheat disease in central parts of Latvia; however, there is insufficient information about the pathogen’s diversity in local conditions. There are three known necrotrophic effectors secreted by P. tritici-repentis – Ptr ToxA, Ptr ToxB, and Ptr ToxC, which induce two types of symptoms – necrosis (Ptr ToxA) or chlorosis (Ptr ToxB and Ptr ToxC). Sequencing of ITS/5.8S region confirmed 21 isolates sampled in Latvia as P. tritici-repentis. The presence of necrotrophic effector encoding genes ToxA, ToxB and toxb was confirmed with specific primers and polymerase chain reaction (PCR). Most of the isolates obtained were from wheat, and 66.6% of isolates from wheat had the ToxA gene that encodes Ptr ToxA production. This effector is causing the formation of necrotic lesions on wheat. Only one isolate obtained from Elymus repens contained genes that encode ToxB genes responsible for protein production that causes chlorosis on susceptible genotypes.
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