Expression of TDM Resistance-Linked ABC1 and ABC2 Transporters in Virulent and Avirulent Cochliobolus sativus Pathotypes

Spot blotch (SB), caused by the fungus Cochliobolus sativus, is most efficiently controlled by using fungicides such as triadimefon (TDM) a triazole group member. This pathogen has the ability to develop resistance against TDM due to its high genetic variability, short lifecycle and plentiful inoculum yield. However, no experimental evidences of the direct contribution of ABC transporters in TDMresistance are available so far. Therefore, changes in ABC1 and ABC2 genes in avirulent Pt1 and virulent Pt4 C. sativus pathotypes were monitored at early time points of TDM treatments using quantitative reverse transcriptase PCR (qRT-PCR). Our results revealed that ABC1 and ABC2 expressions increased in both virulent and avirulent pathotypes at 24 hours post TDM treatments in comparison with non-treated controls. The most outstanding differences in ABC1 and ABC2 expressions were 3.2 and 1.2-fold, in avirulent Pt1 and 4.2 and 1.5-fold respectively, for virulent Pt4, respectively, after 48 hours of 0.125 µg mL-1TDM treatment. According to results, it is likely that ABC1 and ABC2 genes might play a role in signaling actions during C. sativus exposure to triazole fungicides.