Antifungal Mechanism and Efficacy of Kojic Acid for the Control of Sclerotinia sclerotiorum in Soybean

Abstract

Sclerotinia stem rot, which is caused by the fungal pathogen Sclerotinia sclerotiorum, is a soybean disease that results in enormous economic losses worldwide. The control of S. sclerotiorum is a difficult task due to the pathogen’s wide host range and its persistent structures, called sclerotia. In addition, there is lack of soybean cultivars with medium to high levels of resistance to S. sclerotiorum. In this work, kojic acid (KA), a natural bioactive compound commonly used in cosmetic industry, was evaluated for the management of Sclerotinia stem rot. Interestingly, KA showed strong antifungal activity against S. sclerotiorum by inhibiting chitin and melanin syntheses and, subsequently, sclerotia formation. The antifungal activity of KA was not obviously affected by pH, but was reduced in the presence of metal ions. Treatment with KA reduced the content of virulence factor oxalic acid in S. sclerotiorum secretions. Preventive applications of 50 mM KA (7.1 mg/ml) completely inhibited S. sclerotiorum symptoms in soybean; whereas, in curative applications, the combination of KA with prochloraz and carbendazim improved the efficacy of these commercial fungicides. Taken together, the antifungal activity of KA against S. sclerotiorum was studied for the first time, revealing new insights on the potential application of KA for the control of Sclerotinia stem rot in soybean.

Peel Diffusion and Antifungal Efficacy of Different Fungicides in Pear Fruit: Structure-Diffusion-Activity Relationships

“…The antifungal activities of the eleven fungicides were examined using A. alternata HN-5. Briefly, the fungal pathogen was placed in the center of a Petri dish containing PDA medium and 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 30, 40 and 50 mM of each fungicide [ 35 ]. The negative control experiment was performed by culturing A. alternata on PDA in the absence of fungicides.…”

Exogenous genistein enhances soybean resistance to Xanthomonas axonopodis pv. glycines

“…Xag strain NEAU001, which was previously isolated from soybean plants showing bacterial pustule disease symptoms, 28 was used in the experiments. Sclerotinia sclerotiorum strain NJC09, which was isolated from soybean plants showing Sclerotinia stem rot symptoms, 29 was cultured on potato–dextrose agar medium (PDA). PDA medium was prepared by boiling 200 g of potatoes in 1 L of water for 30 min.…”

Identification of New Fusarium sulawense Strains Causing Soybean Pod Blight in China and Their Control Using Carbendazim, Dipicolinic Acid and Kojic Acid

“…For these reasons, methods to decrease the use of this fungicide are urgently needed. On the other hand, dipicolinic and kojic acids are experimental compounds and their antifungal activities have been screened against different fungal plant pathogens [ 35 , 36 , 64 ]. As far as we know, no toxic effects were reported for these compounds, which is an important advantage compared to carbendazim.…”

“…Dipicolinic acid is produced by Bacillus species and is a common component of bacterial spores [ 65 ], while kojic acid is synthesized by some Aspergillus strains and is widely used in the cosmetic industry to protect skin from UV radiation [ 66 ]. Dipiconilic acid was reported to inhibit chitin synthesis in Valsa pyri [ 35 ], whereas kojic acid was demonstrated to block the biosynthesis of melanin in Sclerotinia sclerotiorum [ 36 ].…”

“…The concentration of carbendazim was adjusted to the application rate recommended by suppliers, which suggests the use of 0.8 g carbendazim per kg of seeds for the management of Fusarium [ 34 ]. Dipicolinic (0.84 mg/mL) and kojic acids (0.71 mg/mL) were applied at the same concentrations previously reported [ 35 , 36 ]. After spraying the antifungal compounds, the soybean pods were kept at 28 °C and 90% relative humidity for 24 h. Sterilized ddH 2 O (10 mL) was sprayed in the control treatment.…”