Abstract Detail


Rosli, Roshanizah [1], Metali, Faizah [2], Musselman, Lytton [3], Tennakoon, Kushan [4].

The impact of hemiparasite Cassytha on native and introduced host species.

Cassytha filiformis L. woe vine (laurel family, Lauraceae) is a common hemiparasitic vine in Brunei that is often mistaken for a species of the unrelated Cuscuta (Convolvulaceae). The aims of this study were to determine establishment of Cassytha-host associations, and the parasitic impacts on the photosynthesis, growth and development of the hosts. Field observations have shown that this parasite is often found along the coastlines, having the ability to parasitize 24 host species. We categorized hosts as “starter host” that enables Cassytha to make the initial establishment and “primary woody hosts” that enables to maintain the long-term host-parasitic association. Anatomical studies revealed that haustorial penetration of C. filiformis is primarily enzyme-mediated due to lack of collapsed host cells at the haustorial interface. Xylem-xylem, parenchyma-xylem and parenchyma-parenchyma tissue fusions in the haustorial-host interface were observed, hence sustaining both selective (across membranes) and mass flow of solute uptake from host conducting tissues via xylem tissue grafts. Cassytha filiformis negatively affected the host photosynthetic rates when the ambient light intensity increases.  The effects of C. filiformis parasitism was significant on shrub Dillenia suffruticosa when the photosynthetic photon flux density (PPFD) was at 1500 μmol photons m-2 s-1 and the ambient CO2 concentration (Ca) maintained at 380 μmol mol-1 as compared to the other two hosts, Melastoma malabathricum and Acacia mangium. Furthermore, C. filiformis significantly reduced the chlorophyll content of all infected hosts.  Suppressed photosynthesis of native hosts M. malabathricum and D. suffruticosa, implied eventual decrease in their vigour, thus resulted in plausible impact on Brunei’s native flora. The reduced photosynthetic rates of A. mangium seedlings due to C. filiformis parasitism suggest that the spread of these alien invasive tree seedlings in the field could be controlled by C. filiformis infection.

1 - Universiti Brunei Darussalam, Institute for Biodiversity and Environmental Research, Tungku Link, Gadong, BE 1410, Brunei
2 - Universiti Brunei Darussalam, Environmental and Life Sciences Program, Faculty of Science, Tungku Link, Gadong, BE 1410, Brunei
3 - Old Dominion University, Department Of Biological Sciences, 5155 Hampton Boulevard, Norfolk, VA, 23529, United States
4 - Federation University, School of Health and Life Sciences, Berwick Campus , VIC 3806, Australia

Invasive species
Host-parasite interaction

Presentation Type: Oral Paper
Session: ECOPH3, Ecophysiology III
Location: Virtual/Virtual
Date: Thursday, July 30th, 2020
Time: 4:30 PM
Number: ECOPH3007
Abstract ID:365
Candidate for Awards:Physiological Section Physiological Section Li-COR Prize,Physiological Section Best Paper Presentation

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