Efficacy of antimicrobial compounds in Camellia sinensis for red root pathogen

• Main Author: Chin, Clament Fui Seung
• Format: Thesis
• Language: English; English
• Published: 2010
• Subjects: SB183-317 Field crops Including cereals, forage crops, grasses, legumes, root crops, sugar plants, textile plants, alkaloidal plants, medicinal plants
• Online Access: https://eprints.ums.edu.my/id/eprint/10109/1/24%20PAGES.pdf; https://eprints.ums.edu.my/id/eprint/10109/2/FULLTEXT.pdf; https://eprints.ums.edu.my/id/eprint/10109/

Red root disease of tea is a primary root disease in Sabah Tea Plantation. The causal pathogen was successfully isolated and was identified as Schizopora flavipora, which previously known as Poria hypolateritia. The crude ethanolic extracts of tea ( Camellia sinensis var. assamica) seed, root, stem and leaf; as well as their correspondence fractions (hexane, dichloromethane, ethyl acetate, butanol, and aqueous) were screened in vitro for antifungal activities using disc diffusion technique. Extracts from tea leaf and young immature green stem were more fungistatic than the root and seed extracts. Hexane, dichloromethane and ethyl acetate fractions obtained from the ethanolic leaf extracts by liquid-liquid extractions were more effective than the butanol or aqueous fraction when tested against the pathogen. The compounds that are responsible for fungitoxicity were identified by thin layer chromatography and high performance chromatography to be essential oils, alkaloids, phenolic acids and catechins. The constituents of essential oil that are responsible for fungitoxicity were identified to be geraniol, nerol, nerolidol, linalool, linalool oxide and benzyl acetate by the vanillin-sulphuric acid reagent, with the first two being the more potential, having a minimum inhibitory concentration (MIC) value of 0.25 mg.ml-1 . The groups of non-volatile active compounds were identified as caffeine, gallic acid, catechins and gallic acid esterified catechins, with the first two having the lowest MIC value (0.10 mg.mL-1). The general distribution pattern of the non-volatile active compounds on thirteen parts of the tea plant were further determined and were found to contain highest in leaf bud and lowest in old root cortex. In this study, neither phytoalexins production nor active compounds accumulation was recorded after elicitation treatment using 0.1 % (w/v) chitosan on leaves and roots of two years old tea seedlings. The study demonstrated that leaf extracts of C sinensis exhibit strong fungitoxicity against Schizopora f/avipora, and have potential to be used as mulching materials in infested soils through integrated pest management (IPM) strategy in organic farming, as well as formulating into biopesticide product for the control of red root disease in conventional farming.