Browsing by Author "Edirisinghe, P."

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Exploitation of the Sinhala Royal Youth in the Portuguese Extension of Power
(University of Kelaniya, 2005) Edirisinghe, P.
"The cannon fire employed by the Portuguese was a new startling and often decisive element in warfare in the island (of Ceylon), but the warfare also called into play an unceasing battle of wits and cloak and dagger diplomacy no less than the use of armed soldiers in the field". Into this type of conflict, a technique of catching "young" was used for figures connected to Sinhala royalty with specifically the thrones of Kotte, Jaffna and Kandy. They were required to be converts to the new Christian faith. The paper will examine the following specific personages from Sinhala royalty thus exploited don juan Dharmapala, Karaliyadde Bandara alias Jayaweera, the sons of the lesser queens of Bhuvenekhabahu VII, Prince of Batticaloa, Yamasinghe Bandara alias Don Phillipe, Nikapitiya Bandara, Dom Jaoa (son of Yamasinghe Bandara), Don Juan of Austria alias Konappu Bandara alias Vimala Dharma Surya 1, Dona Catherina alias Princess Kusumasana Devi. The paper concludes by listing the general characteristics of such techniques of psychological warfare and their "successes" and failure in the Sri Lankan context.
Identification and Disease Assessment of Begomovirus Infecting Capsicum frutescens (Kochchi) in Minuwangoda, Sri Lanka
(International Postgraduate Research Conference 2019, Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2019) Jayathilaka, S.A.S.D.; Wanigatunge, R.P.; Attanayake, R.N.; Edirisinghe, P.
Leaf curl of Capsicum frutescens (Kochchi) is a common problem in many Capsicum growing regions of the country including Minuwangoda area in Gampaha. Water stress, poor soil drainage or viral infection are some of the potential causes of leaf curl. The main aim of the current study was to determine whether the leaf curl of Minuwangoda area is due to viral infection and to determine the disease severity and incidence of the region. A disease assessment key graded from 0 to 6 was developed for CLC disease of C. frutescens. Thirtytwo C. frutescens fields having more than 50 plants per field were selected. Disease symptoms, incidence and severity were recorded. Prominent symptoms of the disease were leaf curling, vein yellowing and leaf yellowing followed by severe chlorosis and stunting as the disease progressed. These symptoms were similar to the viral infection. The disease incidence varied from 0 to 100% in the selected fields and 71.88% of the fields in Minuwangoda area were affected. Disease severity in the selected fields ranged from 0 to 6, while the average disease severity of the fields in the area was 1.3. To determine whether the causal agent is a commonly reported virus of the family Begomoviridae, coat protein (CP) gene was amplified from the DNA extracted from infected leaves using CP specific primers and the sequencing was done using the Sanger sequencing method. Sequence alignment with the NCBI database showed a 95% similarity to Chilli leaf curl virus (Begomoviridae) isolate CL-14 from Nochchiyagama. Results indicates that Sri Lankan C. frutescens cultivation could be challenged by the viral infection and control measures should be implemented as soon as possible.
In vitro control of Lasiodiplodia sp. isolated from black banded disease-infected mango (Mangifera indica L.) trees in Sri Lanka
(Faculty of Science, University of Kelaniya, Sri Lanka, 2020) Kularathne, R.; Edirisinghe, P.
Mango (Mangifera indica L.) is indigenous to the Indian subcontinent and extensively grown in Sri Lanka. Black banded disease, which has been reported to reduce the vigor and productivity of mango trees in India, has not been adequately studied in Sri Lanka. The objective of this study was to isolate fungi associated with black banded disease and to determine the effectiveness of selected fungicides and botanicals to control them. This is the first study to isolate and identify the fungi associated with black banded disease in Sri Lanka. Mango twigs of 15 black banded disease-infected trees (willard and karthakolomban cultivars) were collected from different locations in Kuliyapitiya, Anuradhapura, Panadura and Kurunegala regions, and the associated fungi were isolated onto PDA under aseptic conditions. Resultant fungal colonies from all samples had similar characteristics and were identified to genus level using its morphological characteristics and its pathogenicity was confirmed according to Koch’s postulates. Growth inhibition of the resultant fungus was tested in vitro by poison plate method with hot water and cold water leaf extracts of five plant species; Lantana camara, Azadirachta indica, Mirabilis jalapa and Polyalthia longifolia at 20% (w/v) concentration, which have been reported to exhibit antifungal effects. Contact fungicides Captan, Thiram, Mancozeb and Propineb at 100 ppm, 250 ppm, 500 ppm and 750 ppm concentrations incorporated into potato dextrose agar were also tested in vitro for growth inhibition of the isolated fungus at room temperature (30 °C). Black colony and pycnidia forming fungus with cylindrical, septate hyphae was isolated from all infected samples. It was observed to produce immature, hyaline conidia, later turning brown with a septum in the middle. It was identified as Lasiodiplodia sp., and its pathogenicity was confirmed by the development of black mycelial mass on black colored lesions at the site of re-inoculation, similar to the black banded disease. This is contradictory to previous studies in India, where the causative agent has been reported to be Peziotrichum corticolum (Rhinocladium corticolum). Neither hot nor cold water extractions of any of the five plant species showed successful growth inhibition of Lasiodiplodia sp. after 5 days of incubation. Less solubility of active compounds in water or comparatively low concentration used might have been the reasons for the lack of control of fastgrowing Lasiodiplodia. Fungicides Captan and Thiram at 500 ppm and 750 ppm concentrations were most effective in controlling Lasiodiplodia sp. in vitro, with more than 80% inhibition, while Propineb exhibited the least inhibition of the pathogen with less than 10% pathogen inhibition even at 750 ppm, after 7 days of incubation. Thus, the inhibitory effects of Captan and Thiram against the causative pathogen in vivo have to be further evaluated in order to confirm their efficacy in controlling black banded disease in the field.
Intracellular peloton colonization and mycorrhizal associations in epiphytic orchid roots
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Disanayaka, D. M. H. A.; Thathsarani, Y. K. D. D.; Edirisinghe, P.; Senanayake, S. P.
Orchids are highly valued for their esthetic beauty and economic significance, playing a vital role in the global floriculture industry. In their natural habitats, orchids heavily depend on mycorrhizal associations, which influence seed germination, protocorm growth, and nutrition. Despite their importance, understanding these associations remains a challenge. In Sri Lanka, there is limited knowledge exists on the root-associated fungal species interacting with epiphytic orchids and their ecological roles. Exploring the endophytic fungal microbiome in these orchids helps in identifying fungi that form mycorrhizae in epiphytic habitats, paving the way for effective cultivation and developing novel conservation strategies. Intracellular entangled hyphal coils that colonize within the cortex of the roots of epiphytic orchids are known as pelotons. Knowledge of the presence and the distribution of pelotons is crucial for understanding the symbiotic relationships between orchids and mycorrhizal fungi. Therefore, the objective of this study was to investigate the distribution of pelotons in the roots of selected epiphytic orchids. In the present study, sixteen wild-grown and cultivated epiphytic orchid roots belonging to genera, i.e. Dendrobium, Arachnis, and Vanilla were randomly collected from four study sites in tropical lowland, wet and intermediate zones in Sri Lanka. Microscopic imaging of microtome sections was employed to observe the peloton colonization within the randomly sampled orchid roots. Longitudinal and cross-sectional analyses of six orchid root samples revealed sparse colonization of fungal hyphae. Extensive peloton colonization was observed only in the roots of two specimens of Dendrobium sp. and in one specimen of each Arachnis sp. and Vanilla sp. indicating the presence of mycorrhizal fungi in the roots. However, peloton colonization was not found in all the sampled roots of the studied genera. Furthermore, microscopic observations showed that intracellular pelotons were predominantly colonized in the cortex at approximately two centimeters beyond the tip of the roots that are adhered to the substrate. Pelotons were observed as thin hyphal masses ranging from circular and irregular to elongated shapes with hyphae often knotted or spiraled in various dimensions. The study highlighted that wild Dendrobium sp. from Avissawella, Western province, exhibited the highest peloton colonization (5–6 per root cortical cell) with both circular and elongated shapes. In contrast, Arachnis sp. had one irregularly shaped peloton per root cortical cell. Dendrobium sp. from Mahawa, Northwestern province showed both circular and irregular pelotons while Vanilla sp. from Kelaniya, Western province displayed the lowest colonization with irregular pelotons. Irregularshaped pelotons are predominantly found except in Dendrobium sp. from Mahawa, Northwestern province underscoring geographic and genus-specific influences on peloton morphology. These findings enhance the understanding of mycorrhizal associations in orchids and provide valuable information for future research on orchid-mycorrhizal symbioses and their ecological significance.
Morpho-molecular characterization of Lasiodiplodia and Diaporthe species infecting Solanum melongena L. (brinjal) in Gampaha district
(Faculty of Science, University of Kelaniya, Sri Lanka, 2020) Koshila, H.V.A.S.; Dias, R.K.S.; Wanigatunge, R.P.; Edirisinghe, P.
Solanum melongena L. (brinjal) is a vegetable belonging to the family Solanaceae and a popular commodity among consumers. Brinjal plants are infected by numerous fungal pathogens causing a wide range of diseases such as anthracnose by Colletotrichum sp., stem and leaf lesions by Phomopsis vexans (anamorph of Diaporthe), and early blight by Alternaria solani which significantly reduce the yield. The objective of this study was to isolate and identify the fungal pathogens associated with leaves of S. melongena in the Gampaha district. Necrotic or prematurely wilted leaves of S. melongena were collected and associated fungi were isolated onto PDA medium. Pathogenicity was confirmed by wounded and non-wounded inoculation of a seven-day old isolate onto healthy S. melongena leaves and the confirmed fungal pathogens were identified using their morphological, cultural characteristics and analysis of the internal transcribed spacer region (ITS1-5.8S-ITS2). Fifteen fungal isolates were isolated from necrotic leaves of S. melongena. Three fungal isolates (Isolates H32A, H32B and U11) were identified to be pathogenic on leaves of S. melongena based on the pathogenicity test. A necrotic leaf spot was initiated at the site of inoculation with isolates H32A and H32B in both wounded and nonwounded inoculations, which later developed into wilting and premature falling of the leaf. Leaf blight was observed with non-wounded inoculation of isolate U11. Morphological characters of isolates H32A and H32B were similar, with fluffy, blackish-grey, septate mycelia and dark brown oval shape spores with a septum in the middle. Both had similar growth rates of 2.25 cm/day. They were morphologically identified as Lasiodiplodia sp. Yellowish grey color pigmentation was observed in the isolate U11 which produced aseptate hyphae but could not be identified by its morphological characteristics. The nucleotide sequence of ITS region confirmed the morphological identification of isolates H32A (MT990527) and H32B (MT990528) as Lasiodiplodia theobromae with 99.81% sequence similarity to L. theobromae (IRNKB244) at NCBI database. Further, isolate U11 (MT990529) showed 99.82% sequence similarity with Diaporthe eugeniae (ASHM304) at NCBI database. L. theobromae is reported to cause fruit rot in brinjal, while Diaporthe sp. has caused stem and leaf lesions. L. theobromae and D. eugeniae were confirmed to be pathogenic on S. melongena L. (brinjal) plants in the Gampaha district and further studies will be conducted to develop an environmentally friendly strategy to manage above mentioned diseases.
Morphological characterization and molecular identification of three fungal pathogens isolated from Solanum melongena L. in Sri Lanka.
(Journal of Agricultural Sciences – Sri Lanka, 2023) Koshila, H. V.; Wanigatunge, R. P.; Dias, R. K.; Edirisinghe, P.
Purpose: Solanum melongena L. (brinjal/ eggplant) is a popular vegetable in Sri Lanka. Like many solanaceous crops, brinjal fruits and plants are susceptible to various diseases. The objective of this study was to isolate, confirm pathogenicity and characterize fungal pathogens causing leaf blight, yellowing and necrosis in S. melongena plants in selected localities in Gampaha district, Sri Lanka. Research Method: Fungi associated with symptomatic S. melongena plants collected from three localities in Gampaha district, Sri Lanka, were isolated onto potato dextrose agar and their pathogenicity was tested on healthy S. melongena plants. Fungal isolates that were confirmed to be pathogenic were subjected to morphological and molecular characterization. Findings: Fifteen fungal isolates were obtained from infected leaves of S. melongena plants, and four fungal isolates were confirmed to be pathogenic on S. melongena. Isolates H32a and H32b causing similar disease symptoms were identified as Lasiodiplodia theobromae with 99.81% sequence similarity by the analysis of the internal transcribed spacer region (ITS1-5.8S-ITS2). The remaining two pathogenic isolates were identified as Pseudopestalotiopsis theae and Diaporthe eugeniae, with 100% and 99.82% sequence similarities, respectively. Originality/ Value: To our knowledge, this is the first report of leaf necrosis by L. theobromae, leaf yellowing by P. theae and leaf blight by D. eugeniae associated with S. melongena plants in Sri Lanka