Inhibitory Action of Biofungicide Physcion on Initial and Secondary Infection of Magnaporthe oryzae

Abstract

Rice blast, caused by the ascomycete fungus Magnaporthe oryzae, is one of the most destructive plant diseases in the world and a serious threat to global food security. Biofungicide physcion, extracted from roots of Chinese traditional herb rhubarb, has been commercialized to control cucumber powdery mildew (Podosphaera fuliginea) in China as a new active and environmentally-friendly ingredient. This study investigated its bioactivity on rice blast and impact on the infection of M. oryzae. Physcion was effective on M. oryzae with 50% inhibition concentration of 18.19 mg/l on the fungus mycelium growth in vitro and provided 86 and 98% control efficacy in vivo at the concentrations of 40 and 60 mg/l, respectively. It inhibited the initial infection of M. oryzae by inhibiting growth of mycelia, the germination of conidia and the formation of appressoria. Moreover, it inhibited the secondary infection of the fungus at the concentration of 40 mg/l, but had no influence at the low concentrations of 1.25-20 mg/l. So physcion might be a promising natural plant extract that is worthy of being explored to apply on the control of rice blast.

Biosynthesis of Silver Nanoparticles Using Onion Endophytic Bacterium and Its Antifungal Activity against Rice Pathogen Magnaporthe oryzae

“…Many fungi form a specialized infection structure called an appressorium that is necessary and required to penetrate the plant cell walls [ 1 , 6 ]. Therefore, appressorium inhibition significantly reduces the risk of rice fungal pathogens.…”

“…The influence of four concentrations (10, 20, 30 and 40 µg/mL) of AgNPs on the appressorium formation of M. oryzae strain Gry was assessed according to [ 6 ], with slight modification. In brief, 500 μL of spore suspension (1 × 10 5 spores/mL) was added to the same volume of AgNPs in 1 mL tubes with a final concentration of 10, 20, 30 and 40 µg/mL.…”

“…In addition, the cell wall can protect the fungal cells from environmental stresses, such as 237 changes in osmolality, temperature and pH [9,37,38]. Therefore, interference by causing harmful to Many fungi form a specialized infection structure called an appressorium that is necessary and required to penetrate the plant cell walls [1,6]. Therefore, appressorium inhibition significantly reduces the risk of rice fungal pathogens.…”

“…Current control of rice blast disease mainly depends on the use of fungicides. However, the desired goal of controlling the disease has not so far been achieved and there are serious consequences of the excessive use of fungicide on humans, ecosystems and the production of fungicide-resistant strains [ 5 , 6 ]. For all these risks, it is extremely important to find an alternative way to control rice blast disease.…”

Chitosan oligosaccharide alleviates the growth inhibition caused by physcion and synergistically enhances resilience in maize seedlings

“…Physcion refers to a novel biological fungicide, extracted from the root of Rheum palmatum L. , a plant belonging to the family of polygonaceae 18 . It has been extensively found that physcion can be directly absorbed by plants to induce plants to produce defense responses, and it can inhibit the growth of pathogenic fungi, which protects crop plants from damage attributed to diseases 19 . In China, physcion has been widely adopted to prevent and treat powdery mildew, and it is termed as an effective cure for powdery mildew 18 .…”