Mechanisms of Resistance to Triadimefon, an Azole Fungicide in the Barley Spot Blotch Fungus, Cochliobolus sativus


M. Jawhar*, E. Al-Shehadah, H. Alek

Volume 28, Issue 1;
Pages: 62-67; 2022
ISSN: 2069-0053 (print) (former ISSN: 1453-1399), Agroprint;
ISSN (online): 2068-9551


Spot blotch, caused by Cochliobolus sativus is an economical disease of barley worldwide. Resistance C. sativus to Triadimefon (TDM) a triazole compound fungicide has emerged due to its high genetic diversity, short life cycle and plentiful spore production; however, mechanism(s) underlying such TDM-resistance remains unclear. In the current work, expression of four well known genes involved in fungicide resistance mechanisms cytb, MFS, ABC1 and ABC2 were monitored in a highly virulent C. sativus strain (Cs16) at early points of TDM treatments using quantitative real-time PCR (qPCR). Data showed 50% mycelial growth inhibition (EC50) was recorded after 48h at 0.25 µg mL-1 TDM treatment.  The qRT-PCR revealed significant variance in the expression patterns of the four genes at 24 hours post TDM treatments as compared to the non-inoculated controls. It is also noteworthy that maximum expressions for cytb (7.69 -fold), MFS (6.11 -fold), ABC1 (3.4 -fold) and ABC2 (1.7-fold) were recorded at different time points of TDM treatments. The obtained results suggest that these genes, positively activated in C. sativus during TDM applications, which can provide testable hypotheses that will need direct future tests to decide how these changes may be specified in the genome of the virulent C. sativus pathotype.

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