Assessing the Bio-Efficacy of Trichoderma Asperellum (IT13) Against Rhizopus Stolonifer, Fungus Associated with Post-Harvest of Yam (Dioscorea Rotundata) Tubers Rot
Authors:   Department of Biochemistry, Laboratory of Biochemistry, Faculty of Science, University of Douala, Cameroon, NJF Dikongue , M Ntah A Ayong ,   Department of Biochemistry, Laboratory of Biochemistry, Faculty of Science, University of Douala, Cameroon, MLC Nguemnang ,   Department of Biochemistry, Faculty of Science, Antimicrobial Agents Unit, Laboratory of Phytobiochemistry and Medicinal Plant Study, University of Yaounde I, Cameroon, BMA Bedine ,   Phytopathology and Agricultural Zoology Research Unit, Department of Agriculture, Faculty of Agronomy and Agronomic Sciences, University of Dschang, Cameroon, ML Jiogue ,   Department of Biochemistry, Laboratory of Biochemistry, Faculty of Science, University of Douala, Cameroon, NPF Kamsu ,   Department of Biochemistry, Laboratory of Biochemistry, Faculty of Science, University of Douala, Cameroon, NS Tchameni ,   Department of Biochemistry, Laboratory of Biochemistry, Faculty of Science, University of Douala, Cameroon, ML Sameza ,   Department of Biochemistry, Laboratory of Biochemistry, Faculty of Science, University of Douala, Cameroon
Published: December 2024

The aim of this findings was to evaluate the effect of Trichoderma asperellum (It-13) as bio-control agent against Rhizopus stolonifer the causative agent of yam tuber rot. The antagonism test was done by dual culture on Potato Dextrose Agar (PDA). Antibiosis was evaluated on PDA medium by the cellophane membrane method. The production of lytic enzymes (chitinase, cellulase, protease, and lipase) by T. asperellum was detected on PDA supplemented with specific substract. The organic extract was obtained by fermentation of T. asperellum on Potato Dextrose Broth. Total phenols and flavonoids were by spectrophotometer while, Volatile Organic Compounds (VOC) were analysed by Gas Chromatography coupled with Mass Spectrometry (GC-MS). The efficiency of the organic extract on Rhizopus stolonifer was evaluated by poisoning method. The ability of the antagonist to protect yam tuber was done before and after infected the tubers. The results showed that, in dual culture, T. asperellum significantly inhibited the growth of the Rhizopus stolonifer at 48.68 % and 96.42% respectively, in the same media and after growth on cellophane membrane. In the specific solid media, T. asperellum produced chitinase (58.7mm), cellulase (53.8mm), protease (70.0mm) and lipase (50.7mm). The organic extract produced by this strain content total phenol (70.0mg/ml) and flavonoid (30.0mg/ml). The GC-MS analysis of VOC reveal the presence of 17 components with 6-β-hydroxyfluoxymesterone (23.32%), 2-[5-chloro-8-hydroxy-3-methyl-1-oxoisochroman-7-carbonyl) amino]-3-phenyl propionate (18.44%) and acid-2-chloro-5-sulfoaniline (12.02%) as major components. At 75μg/μl, the organic extract had total inhibited (100%) the mycelial growth of Rhizopus stolonifer while, at 107conidia/ml, the spore of T. asperellum (It-13) significantly reduced the necrosis of yam tuber at 25% and 100% respectively, before and after infection with R. stolonifer. These works suggested that the use of Trichoderma asperellum could be serve as alternative to bio-control against post-harvest rot of the yam tubers.