Potential of Biocontrol Agents in Plant Disease Control for Improving Food Safety

Abstract

Plant disease control is mainly based on extraneous application of pesticides to improve agriculture productivity. However, only a part of applied pesticides is used for killing of pathogens and pests. Large part of applied pesticides remains either as residual pesticide or gets volatilized or leached resulting in ecological and environmental problems, and human health hazards. The increased consumer demands for safe food have invigorated research on development of safe and ecofriendly biopesticides. The use of microorganisms for biological control of pests is considered as a pragmatic approach which can drastically lessen the adverse outcomes of agrochemicals in soil. Rhizospheric microorganisms isolated from various crops produce different antagnostic compounds and inhibit the growth of various phytopathogens and insect pests. Moreover, in several plants, hormones like salicylic acid, jasmonic acid and ethylene contribute towards induction of both, systemic acquired as well as induced systemic resitance. In this article, antagonistic rhizosphere microorganisms have been explored for control of phytopathogens. Further, recent advances in field of biopesticides using rhizosphere microorganisms under field conditions is discussed for improvingcrop productivity in sustainable agriculture

Biofertilizers: An ecofriendly technology for nutrient recycling and environmental sustainability

“…Thus, rhizosphere harbours a great abundance of varied microorganisms, several of which support the plants in nutrient procurement from soil and in suppressing pathogenic invasion ( Bulgarelli et al, 2013 ; Leach et al, 2017 ). Plant-associated microbiome includes nitrogen fixers, phosphate-solubilizing bacteria (PSB), mycorrhizal fungi, biocontrol agents, bioremediation agents, plant growth promoting rhizobacteria (PGPR) and pathogenic microbes ( Sehrawat and Sindhu, 2019 ; Singh et al, 2021 ).…”

“…Some microbes secrete phytohormones such as indole acetic acid (IAA), gibberellins (GA) and cytokinins that change root architecture ( Jangu and Sindhu, 2011 ; Duca et al, 2014 ; Khan et al, 2020 ). On the other hand, particular microorganisms isolated from the soil or rhizosphere have been found to inhibit the growth and activity of phytopathogens, and may also alter plant immune responses and community ecology ( Sahu and Sindhu, 2011 ; Sehrawat and Sindhu, 2019 ; Wang et al, 2022 ). Secretion of specific metabolites such as flavonoids, acetosyringone, strigolactones and MBOA (break-down product of root exuded benzoxazinoid) may act as attractant for beneficial microbes and as a signal to trigger plant immunity ( Torres-Vera et al, 2014 ; Hu et al, 2018 ; Phour et al, 2020 ).…”

“…For screening of efficient beneficial microbial strains for use as biofertilizer, microorganisms isolated from the rhizosphere are screened for plant growth-promoting (PGP) traits along with effective colonization ability (Andreozzi et al, 2019; Pandey et al, 2019 ). Various beneficial properties of PGP microbes for utilization as biofertilizer include decomposition of organic matter, enhancing nutrient availability, production of phytohormones and contribution towards mitigation of abiotic and biotic stresses (Lalitha, 2017; Sehrawat and Sindhu, 2019 ; Zhang et al, 2021 ). Biofertilizers comprise of living or latent cells, which are applied either to soil, seed or seedlings for improving nutrients availability and uptake from soil ( Fasusi et al, 2021 ).…”

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“…Biocontrol agents use different mechanisms to shield plants from pathogens (Köhl et al, 2019), which able to reduce the use of agrochemicals in agricultural production (Naamala & Smith, 2020). As described by Sehrawat and Sindhu (2019), many rhizobacteria produce an antagonistic effect by using diverse mechanisms of biocontrol including creating a competitive environment for nutrient uptake against the phytopathogenic microorganisms, the root colonisation ability and producing a secondary metabolite as protective agents.…”

“…In addition, the rhizobacteria also help in regulating the production of virulence factor using quorum sensing and inducing a physical defence mechanism of the host such as induced systemic resistance (ISR) and systemic acquired resistance (SAR) as a mechanism of biocontrol (Sehrawat & Sindhu, 2019). Beneduzi et al (2012) identified PGPBs that indirectly suppress the activity of phytopathogens based on competition for living capacity (space and nutrients) or the development of antibacterial metabolites (Beneduzi et al, 2012).…”