Chitosan and nematophagous fungi for sustainable management of nematode pests

Abstract

Plants are exposed to large number of threats caused by herbivores and pathogens which cause important losses on crops. Plant pathogens such as nematodes can cause severe damage and losses in food security crops worldwide. Chemical pesticides were extendedly used for nematode management. However, due to their adverse effects on human health and the environment, they are now facing strong limitations by regulatory organisations such as EFSA (European Food Safety Authority). Therefore, there is an urgent need for alternative and efficient control measures, such as biological control agents or bio-based plant protection compounds. In this scenario, chitosan, a non-toxic polymer obtained from seafood waste mainly, is becoming increasingly important. Chitosan is the N-deacetylated form of chitin. Chitosan is effective in the control of plant pests and diseases. It also induces plants defence mechanisms. Chitosan is also compatible with some biocontrol microorganisms mainly entomopathogenic and nematophagous fungi. Some of them are antagonists of nematode pests of plants and animals. The nematophagous biocontrol fungus Pochonia chlamydosporia has been widely studied for sustainable management of nematodes affecting economically important crops and for its capability to grow with chitosan as only nutrient source. This fungus infects nematode eggs using hyphal tips and appressoria. Pochonia chlamydosporia also colonizes plant roots endophytically, stimulating plant defences by induction of salicylic and jasmonic acid biosynthesis and favours plant growth and development. Therefore, the combined use of chitosan and nematophagous fungi could be a novel strategy for the biological control of nematodes and other root pathogens of food security crops.

Bionomics and the role of antinemic metabolites of the nematophagous fungus, Pochonia chlamydosporia in suppressing phytonematodes - A Comprehensive Review

“…P. chlamydosporia is a endophyte in root (Mingot-Ureta et al, 2020, Escudero and Lopez-Llorca 2012, Macia-Vicente et al, 2008 and live as a saprophyte in soil (Lopez-Nuñez et al, 2022, Bourne et al, 1996. The endophytic nature of P. chlamydosporia on tomato roots was documented through inoculation of conidiospores and chlamydospores were produced at 10-12 days after inoculation (Swarnakumari and Kalaiarasan 2017).…”

“…The combined utilization of chitinases and chitin deacetylases may elucidate the fungal capacity to decompose nematode eggshells. (Lopez-Nuñez et al, 2022. Extracellular enzyme production by P. chlamydosporia influences the growth of medium and the substrates used, such as chromogenic p-nitrophenyl for chitinases, esterases, lipases & p-nitroanilide for proteinase used for the detection and quantification of enzymes (Esteves et al, 2009).…”

“…The following acronyms are used: CDA for chitin deacetylase, CSN for chitosanase, CSN3A for chitosanase 3 isoform A, FORL for Fusarium oxysporum f. sp. radicis lycopersici, IAA for Indole-3-acetic acid, JA for jasmonic acid, PAL for phenyl ammonia lyase, PM for plasma membrane, RKN for root knot nematode, ROS for reactive oxygen species and SA for salicylic acid (Lopez-Nuñez et al, 2022).…”

“Ectomosphere”: Insects and Microorganism Interactions

“…Chitosan can permeabilise the membrane and kill plant pathogens such as bacteria and fungi in its deacetylated form [ 107 ]. EFs and nematophagous fungi (NFs) are compatible with chitosan since they have evolved low-fluidity membranes [ 108 , 109 ] and branched cell walls rich in β-1,3-glucan [ 110 ]. Moreover, EFs and NFs are in contact with chitin during host (insects and nematodes, respectively) infection.…”

Chitosan flakes for papain immobilization: improving the stability and reusability of the enzyme

“…With its notable biodegradability and antimicrobial properties playing a critical role across industries, chitosan finds application in sectors such as food packaging, agriculture, and healthcare; additionally, it is employed in wound care, sutures, drug delivery, and as a component in biodegradable plastics (Girelli et al, 2020;Wang et al, 2020;Kou et al, 2021;Ribeiro et al, 2021). Chitosan's biocompatibility ensures secure interaction with living tissues, promoting plant growth, and providing a protective shield against pathogens and pests (Maluin and Hussein, 2020;Lopez-Nuñez et al, 2022).…”