Malagasy traditional treatments of infectious plant diseases exert anti-virulence activities against pseudomonas aeruginosa and Ralstonia solanacearum

peer reviewedTraditional Malagasy farmers have developed a range of biological methods to restrict plant diseases without reliance on external or synthetic inputs. Five common Malagasy traditional practices demonstrated to be efficient against potato crop bacterial disease in experimental fields have been investigated for their antibacterial (i.e. bacteriostatic and bactericidal effects) and anti-virulence (i.e. antiquorum sensing and anti-biofilm) activities against two phytopathogens, Pseudomonas aeruginosa and Ralstonia solanacearum. Results show that polar (methanolic) extracts of recipes exert anti-virulence activities rather than bacteriostatic and/or bactericidal activities. Indeed, three recipes (R5, R7 and R9) reduce the expression of QS-dependent virulence factors whereas only recipe (R5) exhibit antibiofilm activities without affecting bacterial growth. R4 and R6 were not active, suggesting other bacterial targets and/or other bioactivity properties. Innovative approaches, inspired from ancestral practices, should be considered in the struggle against infectious diseases to limit the overuse of antibiotics for controlling infectious plant diseases and to reduce the overspread of multidrug resistant bacteria

Malagasy traditional treatments for food crops: A tool to control potato bacterial diseases?

The control and treatment of food crops bacterial diseases remain problematic due to a scarcity of effective phytotreatments. As traditional agricultural practices may represent an attractive venue to explore new treatments, Malagasy traditional practices were investigated for their effectiveness on potato plants. A survey was conducted among Malagasy farmers to collect information on diseases observed on potato crops and on traditional disease control practices. Twelve treatments against potato bacterial diseases were tested on two potato varieties, in experimental plots naturally infected by bacterial wilt disease. The information collected from 52 farmers (i) showed that leaf spots and bacterial wilt disease are the most frequently identified threats for potato crops; and (ii) allowed to identify 12 traditional treatments among which five exhibited protective properties on potato bacterial wilt disease. Moreover, one recipe (R07) was effective on the two potato varieties after two applications per week for 10 weeks, with 50% and 72% effectiveness rate, respectively. Valorization of traditional practices may provide an effective, safe, economic and standardized phytotreatment against potato bacterial wilt disease.SCOPUS: ar.jinfo:eu-repo/semantics/inPres

An Active Fraction from DalbergiaTrichocarpa Baker Disrupts the Formation and Maintenance of Biofilms in Pseudomonas Aeruginosa PAO1

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Sreening of essential oils against rice pathogens isolated from Madagascar

Four predominant isolated pathogens have been identified during survey of rice diseases in three regions in Madagascar. These pathogens were the bacteria Xanthomonas oryzae pv. oryzae and Pseudomonas fuscovaginae and the fungi Alternaria sp. and Curvularia lunata. These pathogens are causing significant yield reduction on rice, which is the staple food in this country. After the identification of those pathogens, the objective of this work was to identify appropriate control measures against them. Plants extracts has been traditionally used to control diseases in other plant species. Nowadays, the problem of residues of phytopharmaceutical product, reinforce the need for research on the development of natural plant extracts to control plant diseases. Madagascar has many endemic plant of interest and we have evaluated the antimicrobial properties of essential oils from Malagasy plants. The main object of this study is the in-vitro screening of essential oils to control the pathogens isolated on rice in Madagascar. Thirty nine essentials oils from Madagascar had been tested. Activity of essentials oils on Pseudomonas fuscovaginae, Alternaria sp. and Curvularia lunata had been tested using broth media and on agar medium for Xanthomonas oryzae pv. oryzae. The growth of the pathogen (bacteria and conidia) in the presence of the essential oil was evaluated and compared to a control. Nine of the 39 essentials oils showed interesting antimicrobial activity with an efficiency more than 70% against at least one bacterial pathogen. One essential oil inhibited the growth of the two pathogens tested. For fungal pathogens, three essential oils presented an efficiency of more than 70% against at least one fungal pathogen. These results confirm that some essential oils present an interesting antimicrobial activity. The in-situ confirmation on plant of this activity is currently ongoing

Antimicrobial Activity of 23 Endemic Plants in Madagascar

Purpose: To screen the crude methanol extracts obtained from 23 endemic plants in Madagascar for antimicrobial activity. Methods: In order to assess the antimicrobial properties of the extracts, their minimum inhibitory concentrations (MICs) were obtained using the broth microdilution method. The six test pathogenic species used were Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Salmonella typhi, Pseudomonas aeruginosa and Candida albicans. Bioautography agar overlay test and phytochemical screening were also performed on the most active extracts. Results: From the 23 plants tested, 16 of which are used in traditional medicine, Poivrea phaneropetala (Combretaceae), Koehneria madagascariensis (Lythraceae) and Rhopalopilia perrieri (Opiliaceae) exhibited the broad spectrum of activity, being active against all the test organisms, while Monoporus clusiifolius (Myrsinaceae) showed the strongest antifungal activity against Candida albicans with a minimal inhibitory concentration of 0.250 mg/ml. Bioautography and phytochemical analysis of the five active extracts against bacterial strains and of one active extract against C. albicans indicate that the active compounds responsible for antimicrobial activity may be mainly flavonoids and/or terpenes. Conclusion: These preliminary results are the first antimicrobial studies on these plants and lend support for the use of some of them in traditional medicine

Malagasy traditional treatments of infectious plant diseases exert anti-virulence activities against pseudomonas aeruginosa and Ralstonia solanacearum

Traditional Malagasy farmers have developed a range of biological methods to restrict plant diseases without reliance on external or synthetic inputs. Five common Malagasy traditional practices demonstrated to be efficient against potato crop bacterial disease in experimental fields have been investigated for their antibacterial (i.e. bacteriostatic and bactericidal effects) and anti-virulence (i.e. antiquorum sensing and anti-biofilm) activities against two phytopathogens, Pseudomonas aeruginosa and Ralstonia solanacearum. Results show that polar (methanolic) extracts of recipes exert anti-virulence activities rather than bacteriostatic and/or bactericidal activities. Indeed, three recipes (R5, R7 and R9) reduce the expression of QS-dependent virulence factors whereas only recipe (R5) exhibit antibiofilm activities without affecting bacterial growth. R4 and R6 were not active, suggesting other bacterial targets and/or other bioactivity properties. Innovative approaches, inspired from ancestral practices, should be considered in the struggle against infectious diseases to limit the overuse of antibiotics for controlling infectious plant diseases and to reduce the overspread of multidrug resistant bacteria.SCOPUS: ar.jinfo:eu-repo/semantics/publishe