Biological Control of Late Leaf Spot of Peanut (Arachis hypogaea) with Chitinolytic Bacteria

Abstract

Late leaf spot (LLS), caused by Phaeoisariopsis personata, is a foliar disease of groundnut or peanut (Arachis hypogaea) with high economic and global importance. Antifungal and chitinolytic Bacillus circulans GRS 243 and Serratia marcescens GPS 5, selected among a collection of 393 peanut-associated bacteria, were applied as a prophylactic foliar spray and tested for control of LLS. Chitin-supplemented application of B. circulans GRS 243 and S. marcescens GPS 5 resulted in improved biological control of LLS disease. Supplementation of bacterial cells with 1% (wt/vol) colloidal chitin reduced lesion frequency by 60% compared with application of bacterial cells alone, in the greenhouse. Chitinsupplemented application of GRS 243 and GPS 5 also resulted in improved and stable control of LLS in a repeated field experiment and increased the pod yields by 62 and 75%, respectively, compared with the control. Chitin-supplemented application of GPS 5 was tested in six onfarm trials, and the increase in pod yields was up to 48% in kharif (rainy season). A 55-kDa chitinase was purified from the cell-free culture filtrate of GPS 5 by affinity chromatography and gel filtration. Purified chitinase of S. marcescens GPS 5 (specific activity 120 units) inhibited the in vitro germination of P. personata conidia, lysed the conidia, and effectively controlled LLS in greenhouse tests, indicating the importance of chitinolysis in biological control of LLS disease by GPS 5.

Exploring interactions of plant microbiomes

“…The microbial communities found in the phyllosphere have essential roles in processes related to plant development, for example, performing nitrogen fixation, protecting plants against invading pathogens and biosynthesizing phytohormones (Jones, 1970;Freiberg, 1998;Brandl et al, 2001;Kishore et al, 2005). It makes them important pieces of global processes, such as carbon sequestration (Bulgarelli et al, 2013), and they can be used as potential sources for the development of sustainable agricultural practices.…”

Screening endophytic actinobacteria with potential antifungal activity against Bipolaris sorokiniana and growth promotion of wheat seedlings

“…Microbial enzymes, especially chitinases, are highly important in biocontrol strategies due to their ability (a) to degrade chitin (the main component of the cell wall of most fungi), (b) to inhibit the germination of fungal spores and the elongation of the germinative tube, and (c) to lyse hyphae (Kishore et al, 2005).…”

El género Bacillus como agente de control biológico y sus implicaciones en la bioseguridad agrícola

“…These enzymes are responsible for the degradation of the main polysaccharides that make up the cell wall of the fungi, by the hydrolysis of their glycosidic bonds ( Figure 5). There are currently diverse scientific studies that report the role of these enzymes in the in vitro antifungal activities obtained from strains of the Bacillus genus (Kishore et al, 2005;Shafi et al, 2017). For example, Yan et al (2011) demonstrated the role a chitinase in the control of Rhizoctonia solani by B. subtilis SL-13, evaluating the inhibitory activity of the purified enzyme, confronted with this pathogen.…”

“…Estas enzimas son responsables de la degradación de los principales polisacáridos que conforma la pared celular de hongos, mediante la hidrólisis de sus enlaces glucosídicos (Figura 5). Actualmente, existen diversos estudios científicos que reportan el papel de estas enzimas en la actividad antifúngica in vitro obtenidas de cepas del género Bacillus (Kishore et al, 2005;Liu et al, 2010;Shafi et al, 2017). Por ejemplo, Yan et al (2011) demostraron el papel de una quitinasa en el control de Rhizoctonia solani por B. subtilis SL-13, evaluando la actividad inhibitoria de la enzima purificada y confrontada contra dicho patógeno.…”