Evaluation of Pyrenophora tritici-repentis Infection of Wheat Heads

Abstract

The incidence of wheat head infection by Pyrenophora tritici-repentis (Ptr), the etiological agent of tan spot disease, was evaluated during grain development in a glasshouse experiment. Heads artificially inoculated with a Ptr spore suspension developed widespread brown spots across the spikelets, and mycelia and conidophores were observed on glumes and awns. Seeds of heavily infected heads were darkened and shrivelled, but no red smudge symptoms were apparent. The recovery rate of Ptr isolates from the inoculated wheat heads was low, and colonies that were re-isolated displayed an irregular morphology with reddish mycelia when grown on agar plates. The presence of Ptr on inoculated wheat heads was assessed directly via PCR detection, and a limitation of Ptr hyphae to proliferate beyond the point of contact of spore inoculum on floret tissues was observed. The systemic transmission of Ptr from infected seeds was minimal; however, saprophytic growth of the pathogen occurred on the senescing leaves of wheat plants grown from inoculated seeds. Thus, even though Ptr seed infection is not as common as foliar infection, infected seeds are still a source of disease inoculum and screening for pathogen contamination is advisable.

Detection and characterization of QoI resistance in Pyrenophora tritici‐repentis populations causing tan spot of wheat in Argentina

“…However, the impact of fungicide resistance and its relationship with the epidemiological role of infected seed has not been adequately discussed. Ptr‐infected seeds are a source of disease inoculum (See et al, 2020) and the transmission of Ptr from the infected seed to the seedling occurs with high efficiency in the field (Carmona et al, 2006). In this way, the introduction of Ptr strains into a field is a consequence of planting infected seeds or inefficiently treated seeds (long‐distance dissemination).…”

Durum Wheat Mediterranean Landraces: A Valuable Source for Resistance to Tan Spot Disease

“…Under favorable conditions for disease development, tan spot can cause up to 50% yield losses and reduce grain quality by the formation of red or pink smudge, particularly in durum wheat [17,[26][27][28]. Several management strategies such as the use of non-host plants in the crop rotation, chemical control, and wheat variety genetics are available.…”

Does Abiotic Host Stress Favour Dothideomycete-Induced Disease Development?

“…Several Dothideomycetes affect crops used as staple food around the world. To list only a few, Zymoseptoria tritici (teleomorph Mycosphaerella graminicola) and Dreschlera tritici-repentis (teleomorph Pyrenophora tritici-repentis), the causative agents of Septoria tritici blotch and tan spot, respectively, are major pathogens of wheat worldwide [20,21], and black Sigatoka disease caused by Pseudocercospora fijiensis (teleomorph Mycosphaerella fijiensis) remains a threat to banana production in many countries [22,23]. Given that all climate change models forecast an increase in abiotic stress to crops around the world and that these stresses have an impact on plant-pathogen interactions, it is important to understand how abiotic stresses can affect disease prevalence and severity.…”