Mode of action and efficacy of quinolinic acid for the control of Ceratocystis fimbriata on sweet potato

BACKGROUND Ceratocystis fimbriata is a hazardous fungal pathogen able to cause black rot disease on sweet potato. The management of C. fimbriata strongly relies on the use of toxic fungicides, and there is a lack of efficient alternative strategies. RESULTS The antifungal properties of quinolinic acid (QA) were studied for the first time, indicating that QA shows selective antifungal activity against C. fimbriata. QA inhibited completely the mycelial growth of C. fimbriata at less than 0.8 mg mL(-1) concentration (pH 4), and was able to produce alterations in the fungal cell wall, and to impede spore agglutination and mycelium formation. QA significantly reduced the concentration of ergosterol, and was able to associate to iron (II), suggesting that QA may be a lanosterol 14-alpha demethylase inhibitor. In preventive applications, QA reduced the disease incidence of C. fimbriata on sweet potato by 75%, achieving higher control efficacy in comparison with commercial fungicides prochloraz and carbendazim. CONCLUSIONS The first selective antifungal agent against C. fimbriata was discovered in this work, and showed suitable antifungal properties for the management of black rot disease.

Automated summary

The antifungal properties of quinolinic acid (QA) against Ceratocystis fimbriata were studied for the first time, showing selective antifungal activity. QA demonstrated complete inhibition of mycelial growth, alteration of fungal cell wall, and reduction of ergosterol concentration, suggesting its potential as a lanosterol 14-alpha demethylase inhibitor. Preventive applications of QA reduced disease incidence by 75%, exhibiting higher control efficacy compared to commercial fungicides.