Fungicide Tolerance and Effect of Environmental Conditions on Growth of Trichoderma spp. with Antagonistic Activity Against Sclerotinia sclerotiorum Causing White Mold of Common Bean (Phaseolus vulgaris)

The present study was conducted to evaluate in vitro compatibility of commonly used agrochemicals as well as the effect of temperature, pH and salt on the growth of six Trichoderma spp. with antagonistic activity against S. sclerotiorum responsible for white mold of common bean. The results revealed that in dual culture, the mycelial growth inhibition of S. sclerotiorum ranged from 83.4 to 87.4 %25. The highest inhibition (87.4 %25) was obtained with isolate T. erinaceum It-58, while the lowest inhibition (83.4 %25) was caused by T. koningiopsis It-21. Except T. asperellum It-13, antagonistic fungi were able to fully colonized pathogen in five days reaching class I antagonism according to Bell scale. The maximum inhibition percentage of volatile (54.07 %25) and non-volatile compounds (68.89 %25) on pathogen was respectively caused by T. asperellum It-13 and T. harzianum P-11. Fungicides affect the growth of Trichoderma differently. No growth was observed while testing compatibility of T. asperellum It-13 and T. erinaceum It-58 with Mancozeb as well as T. asperellum It-13 and T. afroharzianum P-8 with Methyl thiophanate illustrating the absence of compatibility. The excellent growth rate of Trichoderma was found at temperature range of 25ndash%253B30˚C and pH range 4.5-5.5. Apart from T. asperellum It-13, all the isolates were able to grow at NaCl concentrations up to 1000 micro%253BM and were identified as superior salt-tolerant isolates

Antioxidant and Antifungal Activities of Cocoa Butter (Theobroma cacao), Essential Oil of Syzygium aromaticum and a Combination of Both Extracts against Three Dermatophytes

To contribute in the research of better drugs against dermatophytosis, we evaluated the antioxidant and antidermatophytic activities of cocoa butter, cloves essential oil, and a mixture of both extracts. The cocoa butter was obtained by boiling the cocoa paste. The essential oil extracted by hydrodistillation was chemically analysed by gas chromatography and gas chromatography coupled with mass spectrometry. The antioxidant activity was determined using the DPPH scavenging method, and  the antidermatophytic activity was evaluated using the agar dilution method. The essential oil, majoritary constituated by eugenol (87.62%), β-caryophyllene (5.88%), and β-bisabolene (4.41%), had an antiradical power (4.22 x 10-2) higher than that of BHT (4.00 x 10-3), like the cocoa butter and essential oil mixture (6.06 x 10-3). The essential oil was more active than the griseofulvin: it was fungicidal at 400 ppm against Trichophyton rubrum, and at 900 ppm against Microsporum gypseumand Trichophyton tonsurans. The cocoa butter activity was low, but the mixture with the essential oil had an important activity with inhibitory percentages of 78.69 %, 88.27 %, 91.20% against T. rubrum (at 400 ppm), T. tonsurans(at 900 ppm)and M. gypseum (at 900 ppm)respectively. Cloves essential oil and the mixture with cocoa butter can be used to formulate new drugs against dermatophytes.

Antagonistic fluorescent Pseudomonads: rhizobacteria with suppressive and plant growth promoting properties against Phytophthora colocasiae, the causal agent of taro leaf blight

Taro leaf blight caused by Phytophthora colocasiae affects plant health and is a major threat to taro culture in Cameroon. Chemical fertilizers used often harm the ecosystem. Plant growth-promoting rhizobacteria (PGPR) are better alternatives that increase plant growth promotion and suppress phytopathogens. In the present study, a total of 67 fluorescent Pseudomonas spp. was characterized by 17.91, 5.97, and 4.47% populations of P. fluorescens, P. chlororaphis, and P. putida, respectively, among the most represented. More than 36% of bacteria showed antagonistic potential through the production of both diffusible and volatile compounds. Some of them (03) exhibited antagonistic activity in dual culture against P. colocasiae with a diameter greater than 13 mm. These rhizobacteria produced a significant amount of siderophore, IAA, SA, HCN, protease, lipases, and cellulases. For the pot experiment, treatment by Pseudomonas significantly increased the enzymatic activity involved in the resistance of taro, such as peroxidase (PO), polyphenol oxidase (PPO), and phenylalanine ammonia-lyase (PAL). The two antagonists also increased plant growth parameters of taro such as chlorophyll, plant height, shoot length, total leaf surface, fresh root biomass, and fresh leaf biomass. These findings showed that fluorescent Pseudomonas have an intriguing and undeniable potential in the fight against P. colocasiae, which could lead to the development of a biopesticide in the future

Cameroonian medicinal plants belonging to Annonaceae family: radical scavenging and antifungal activities

The free-radical scavenging activity of ethanolic and methanolic extracts of leaves, stems and roots of Annona muricata, Monodora tenuifolia, Uvaria comperei, Uvaria muricata and Xylopia africana was evaluated using DPPH and ORAC assays. Further, phytochemical analysis, total phenolic and total flavonoid contents were also determined. Moreover, the antifungal activity of extracts was studied. The findings indicated that A. muricata and U. comperei extracts own antiradical activities and moderate antifungal properties

Investigations of the essential oils of some aframomum species (Zingiberaceae from Cameroon) as potential antioxidant and anti-inflammatory agents

International audienc

Antagonism of Trichoderma asperellum against Phytophthora megakarya and its potential to promote cacao growth and induce biochemical defence

This work aimed to assess the antagonism effects of four different Trichoderma asperellum isolates against Phytophthora megakarya and their ability to enhance cacao growth and biochemical defence. Results showed that In paired culture, all the isolates of T. asperellum used were antagonistic to P. megakarya by means of mycoparasitism. In pot experiments, leaf number, plant height, shoots and root dry matter were significantly increased by T. asperellum. Similarly, chlorophyll rate, P uptake and acid phosphatase activities were also increased. These antagonists reduced significantly the effects of P. megakarya in the leaves of cacao plants. Amino acid and phenolic components content increased in either healthy or infected leaves from cacao plants inoculated with T. asperellum. There was negative correlation between both phenolic compounds and disease severity and amino acids and disease severity. This suggests that these compounds are involved in disease resistance. In fact, the induction of specific amino acids such as alanine, glutamic acid and methionine may play an important role in the adaptation of cacao plant to P. megakarya infection. These findings demonstrated that Trichoderma asperellum (PR10, PR11, PR12 and PR659-7) could be used to improve the development of cacao plants and protect the plant against Phytophthora megakarya

Chemical composition, antiradical and antifungal activities of essential oil of the leaves of Cinnamomum zeylanicum Blume from Cameroon

International audienc

Identification of native soil-derived Trichoderma spp. isolates and analysis of their antagonist traits against Lasiodiplodia theobromae causing stem-end rot in papaya

International audienceIdentification of native soil-derived Trichoderma spp. isolates and analysis of their antagonist traits against Lasiodiplodiatheobromae causing stem-end rot in papaya, Archives of Phytopathology and Plant Protection

Potential use of Eucalyptus globulus essential oil against Phytophthora colocasiae the causal agent of taro leaf blight.

International audienceThis study was carried out to determine the antimicrobial activity of essential oil derived from leaves of eucalyptus (Eucalyptus globulus) against Phytophthora colocasiae, the causal agent of taro leaf blight (TLB). Essential oil was obtained by Clevenger-type water distillation. The major compounds in this essential oil were identified using gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC/MS). Antimicrobial activity of the essential oil was tested in vitro against mycelial growth, sporangia and zoospores germination of P. colocasiae. Additionally, in situ tests were conducted on detached healthy taro leaves discs and evaluating necrosis symptoms of TLB were assessed. Results of the chemical composition of the essential oil analysis showed that, 1.8-cineole (26.4 %), α-pinene (14.1 %) and p-cymene (10.2 %) are the most abundant compounds. In addition, four components could be identified in noticeable amounts (18.1 % in the total): regulator G1/G2 and its derivatives as well as flavesone, a regulator G3 derivative. G is a generic term for a family of 2,3-dioxabicyclo[4,4,0] decane system growth regulators. Here, G-regulators and derivatives are described for the first time in E. globulus. Antimicrobial activity of the essential oil was recorded with total inhibition of mycelia growth and sporangia germination at 0.625 mg/ml, while the complete inhibition of zoospores germination was recorded at 0.156 mg/ml. In situ results showed that essential oil completely inhibited the appearance of disease symptoms, necrosis development and sporulation at 3.5 mg/ml. These results demonstrated that, the essential oil of Eucalyptus globulus has high ability to inhibit the development of P. colocasiae, and might be used for controlling TLB

Cameroonian medicinal plants belonging to Annonaceae family: radical scavenging and antifungal activities

<p>The free-radical scavenging activity of ethanolic and methanolic extracts of leaves, stems and roots of <i>Annona muricata</i>, <i>Monodora tenuifolia</i>, <i>Uvaria comperei</i>, <i>Uvaria muricata</i> and <i>Xylopia africana</i> was evaluated using DPPH and ORAC assays. Further, phytochemical analysis, total phenolic and total flavonoid contents were also determined. Moreover, the antifungal activity of extracts was studied. The findings indicated that <i>A. muricata</i> and <i>U. comperei</i> extracts own antiradical activities and moderate antifungal properties.</p