Antifungal Mechanism of Dipicolinic Acid and Its Efficacy for the Biocontrol of Pear Valsa Canker

Abstract

Valsa pyri is a fatal canker pathogen that causes significant reduction of crop yield in pear orchards. V. pyri invades the trunk phloem, and is difficult to control by chemical treatment. In this work, it was found for the first time that Bacillus subtilis-produced dipicolinic acid (DPA) exhibits antifungal activity against different canker pathogens, including Alteraria alternata, Botryosphaeria dothidea, Rhizoctonia solani, and V. pyri. Growth inhibition of V. pyri was observed at less than 5 mM concentration (pH = 5.6). DPA showed the highest antifungal activity at acidic pH values and in the presence of bivalent metals, such as zinc(II), cobalt(II), and copper(II). Measurement of mRNA expression levels and scanning electron microscope (SEM) observations revealed that DPA causes V. pyri apoptosis via inhibition of chitin biosynthesis and subsequent cell lysis. Interestingly, DPA showed high stability in the pear bark and was able to cross the pear tree bark into the phloem, protecting the internal phases of the pear trunk. In preventive applications, DPA reduced the canker symptoms of V. pyri on Cuigan pear trees by 90%. Taken together, an efficient strategy for the management of V. pyricaused canker disease was developed using a novel antifungal agent, DPA, with strong antifungal activity and particular diffusion properties.

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

“…Isolation and identification of the pathogen are described in Supplementary Figure S1 . The isolation of Valsa pyri strain Vp297, Colletotrichum brevisporum strain GM1, and Botryosphaeria dothidea isolate SBL303 was previously reported by our research group ( Chen et al, 2020 ; Shi et al, 2020 ; Song et al, 2020 ). Fungal strains were cultured on potato–dextrose–agar (PDA) medium (200 g potato, 20 g dextrose, and 15 g agar in 1 L water) at 28°C.…”

Antibacterial mechanism of Biochanin A and its efficacy for the control of Xanthomonas axonopodispv.glycines in soybean

“…RNA extraction was carried out as previously reported by our research group. 24,25 Briefly, Xag was grown in LB medium (50 mL) containing 0 and 50 μg/mL Biochanin A at 28°C and 200 rpm for 24 h. Then, the bacterial suspensions were centrifuged at 4°C and 10 000 rpm for 10 min, and the cells were harvested and washed twice with 200 μL of water. Total RNA was extracted using TRIzol reagent (Ambion, California, USA).…”

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

“…Despite QA and dipicolinic acid showing similar structural characteristics, both compounds showed very different antifungal properties. Dipicolinic acid showed broad spectrum antifungal activity and a mode of action based on the inhibition of chitin biosynthesis, 16 whereas QA showed selective antifungal activity against C. fimbriata and was found to inhibit ergosterol biosynthesis.…”

“…C. fimbriata was grown on PDA medium at 28 °C for 5 days, and the mycelium was divided into 3‐mm‐diameter plugs. Then, the formation of conidia was induced by culturing three plugs of C. fimbriata in 40 mL barley‐honey‐tryptone medium at 28 °C and 200 rpm for 24 h. Barley‐honey‐peptone medium was prepared as previously indicated 16 . The formed conidia were collected by centrifuging at 10 000 rpm and °C for 10 min.…”

“…Recently, our research group reported the broad spectrum of antifungal activity of 2,6‐dipicolinic acid, which consists of a pyridine structure with two carboxylic acid moieties at positions 2 and 6 16 . In this work, we examined for the first time the antifungal properties of quinolinic acid (QA) (Fig.…”