Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.602338
Title: Detection, control and resistance expression in oil palm (Elaeis guineensis) caused by Fusarium oxysporum f.sp. elaeidis
Author: Rusli, Mohd Hefni
Awarding Body: University of Bath
Current Institution: University of Bath
Date of Award: 2012
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Abstract:
Vascular wilt disease. caused by Fusariun: oxysporum f. sp. elaeidis (Foe) causes. a devastating disease of oil palm in West and Central Africa. However, this disease has not been reported in South East Asia, in spite of long term importation for breeding purposes of African seed and pollen, known to be often contaminated with Foe. Malaysia is the second largest palm oil producer in the world and Foe remains a major threat to this industry, especially as this study shows four current palm genotypes grown there are susceptible. This research was conducted in order to help Malaysia avoid and/or be prepared for this potential problem. Disease epidemiology was studied in plantations in Ghana. Statistical analysis showed the disease mainly occurred in clusters, implying root-root transmission rather than aerial spread by spores. Many Foe isolates were obtained for genetic analysis from diseased palms, including 10 per cent from 21 symptomless trees. This shows that visual disease surveys are flawed. The only practical, sustainable approach to controlling Fusarium is by breeding disease resistant palm lines. The success of this strategy depends on the variability of Foe isolates. Resistance should be stable because this analysis showed Foe isolates have a monophyletic origin. Moreover, this study also showed early responses to Foe infection of roots through induction of the defence-related gene chitinase. Molecular diagnostic tools were developed for (1) rapid detection and quantification of Foe in seed and pollen for quarantine purposes in order to prevent transcontinental spread of Foe, (2) to test efficacy of putative disease resistant or tolerant palm genotypes, and (3) to facilitate epidemiological studies involving palm tissues and soils. Primers were designed for detecting the species F. oxysporum, based on the translation elongation factor gene (TEF- 1 a), superior to the existing ones used currently at quarantine. The first Foe-specific primers to be developed were based on a .virulence effector gene that excluded 70 other phyla genetically closely related Fusarium species from various hosts and origins. Treatment by fungicides is undesirable and largely unsuccessful for this disease. For that reason, the mycoparasitic fungus Trichoderma was evaluated. The most effective strains were selected based on discerning techniques such as competition in palm wood and survival in soil and on roots, Trichoderma isolate TPP4 was shown to exhibit potential biological control by delaying and Suppressing Fusa,;um wilt symptoms and colonization. Confocal microscopy was used to investigate Interactions on the root surface between Foe and Tffchoderma, which had been transformed with red and green fluorescent proteins respectively. Disease progress/extentsymptoms was substantially delayed/reduced In two Malayslan soils compared to other growth media, highlighting' the possibility that Foe-suppressive soils in Malaysia might explain the non-appearance of this vascular disease there.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.602338  DOI: Not available
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