Fungal diseases result in significant losses of fruits and vegetables during handling, transportation and storage. At present, post-production fungal spoilage is predominantly controlled by using synthetic fungicides. Under the global climate change scenario and with the need for sustainable agriculture, biological control methods of fungal diseases, using antagonistic microorganisms, are emerging as ecofriendly alternatives to the use of fungicides. The potential of microbial antagonists, isolated from a diversity of natural habitats, for postharvest disease suppression has been investigated. Postharvest biocontrol systems involve tripartite interaction between microbial antagonists, the pathogen and the host, affected by environmental conditions. Several modes for fungistatic activities of microbial antagonists have been suggested, including competition for nutrients and space, mycoparasitism, secretion of antifungal antibiotics and volatile metabolites and induction of host resistance. Postharvest application of microbial antagonists is more successful for efficient disease control in comparison to pre-harvest application. Attempts have also been made to improve the overall efficacy of antagonists by combining them with different physical and chemical substances and methods. Globally, many microbe-based biocontrol products have been developed and registered for commercial use. The present review provides a brief overview on the use of microbial antagonists as postharvest biocontrol agents and summarises information on their isolation, mechanisms of action, application methods, efficacy enhancement, product formulation and commercialisation.

Exploitation of microbial antagonists for the control of postharvest diseases of fruits: a review

Salinity stress is one of the major abiotic stresses limiting crop production in arid and semi-arid regions. Interest is increasing in the application of PGPRs (plant growth promoting rhizobacteria) to ameliorate stresses such as salinity stress in crop production. The identification of salt-tolerant, or halophilic, PGPRs has the potential to promote saline soil-based agriculture. Halophytes are a useful reservoir of halotolerant bacteria with plant growth-promoting capabilities. Here, we review recent studies on the use of halophilic PGPRs to stimulate plant growth and increase the tolerance of non-halophytic crops to salinity. These studies illustrate that halophilic PGPRs from the rhizosphere of halophytic species can be effective bio-inoculants for promoting the production of non-halophytic species in saline soils. These studies support the viability of bioinoculation with halophilic PGPRs as a strategy for the sustainable enhancement of non-halophytic crop growth. The potential of this strategy is discussed within the context of ensuring sustainable food production for a world with an increasing population and continuing climate change. We also explore future research needs for using halotolerant PGPRs under salinity stress.

/pdf/mining-halophytes-for-plant-growth-promoting-halotolerant-1rh0jrfxd3.pdf

Mining Halophytes for Plant Growth-Promoting Halotolerant Bacteria to Enhance the Salinity Tolerance of Non-halophytic Crops.

https://www.scielo.br/pdf/bjm/v43n3/46.pdf

Bacterial exopolysaccharide and biofilm formation stimulate chickpea growth and soil aggregation under salt stress

Halotolerant plant growth–promoting bacteria: Prospects for alleviating salinity stress in plants

/pdf/bacteria-in-agrobiology-crop-ecosystems-4itmo41pw2.pdf

Bacteria in Agrobiology: Crop Ecosystems

Aims: Grey mould caused by Botrytis cinerea is an economically important disease of strawberries in Tunisia and worldwide. The aim of this study was to select effective halophilic bacteria from hypersaline ecosystems and evaluate the abilities of antifungal bacteria to secrete extracellular hydrolytic enzymes, anti-Botrytis metabolites and volatiles.



Methods and Results:  Grey mould was reduced in strawberry fruits treated with halophilic antagonists and artificially inoculated with B. cinerea. Thirty strains (20·2%) were active against the pathogen and reduced the percentage of fruits infected after 3 days of storage at 20°C, from 50% to 91·66%. The antagonists were characterized by phenotypic tests and 16S rDNA sequencing. They were identified as belonging to one of the species: Virgibacillus marismortui, B. subtilis, B. pumilus, B. licheniformis, Terribacillus halophilus, Halomonas elongata, Planococcus rifietoensis, Staphylococcus equorum and Staphylococcus sp. The effective isolates were tested for antifungal secondary metabolites.



Conclusions:  Moderately halophilic bacteria may be useful in biological control against this pathogen during postharvest storage of strawberries.



Significance and Impact of the study:  The use of such bacteria may constitute an important alternative to synthetic fungicides. These moderate halophiles can be exploited in commercial production and application of the effective strains under storage and greenhouse conditions.

/pdf/biological-control-of-grey-mould-in-strawberry-fruits-by-25ivmi7bok.pdf

J.L. Cayol

Papers

Biological control of grey mould in strawberry fruits by halophilic bacteria.