Plant and Molecular Biology

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Author: search.filters.author.Kannangara, Sagarika

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    The mycoremediation potential of phyllosphere fungi in urban ornamental plants in Sri Lanka with mathematical models for PAH degradation
    (2024) Dharmasiri, Nadeema; Kannangara, Sagarika; Undugoda, Lanka; Munasinghe, Jayantha; Madushika, Ruvini; Thambugala, Kasun M.; Gunathunga, Chathuri; Pavalakumar, Dayani
    Currently, phylloremediation has emerged as a highly effective method for eliminating air pollutants, particularly polyaromatic hydrocarbons (PAHs). When PAHs accumulate on the phyllosphere, they significantly impact the fungal communities residing on leaf surfaces. This study aimed to investigate how pollution distribution patterns affect the diversity and PAHdegrading abilities of phyllosphere fungi, alongside identifying suitable mathematical models for PAH degradation. Leaf samples from two locations, Maradana and Sapugaskanda, were identified as having the highest PAH concentrations through principal component analysis. The fungal diversity in these highly contaminated regions was varied, with dominant species exhibiting greater PAH-degrading capabilities than those in less polluted areas. Thirty-five morphologically different epiphytic fungal strains were isolated on Potato Dextrose Agar (PDA) medium using the sample leaf wash. Two different fungal strains were selected as the best PAH degraders among those 35 different strains. These fungal strains were identified as Trichoderma harzianum P4M-16, and Fusarium solani P11M-46 based on ITS sequence data. Notably, these fungal species were more prevalent in highly polluted urban areas compared to less contaminated sites. High-Performance Liquid Chromatography (HPLC) analysis revealed that these two fungal species degrade PAHs more efficiently than others. Their kinetics assays demonstrated alignment with four degradation models when breaking down phenanthrene, naphthalene, pyrene, and anthracene. Scanning electron microscopy images showed that these fungi function as endophytes, extending their mycelium into the core leaf tissue layers beyond the epidermis. Gas Chromatography-Mass Spectrometry (GCMS) analysis indicated
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    Nature and activities of microfungi associated with the decomposition of rice straw in Sri Lanka
    (Asian Journal of Agriculture and Biology, 2022) Undugoda, Lanka; Kannangara, Sagarika
    Agricultural sustainability through crop residue biodegradation is an eco-friendly method to enrich soil fertility essential to agricultural countries. Rice straw, rich in cellulose, is the primary source of organic matter, enhancing the fertility in rice fields and is a better alternative to replace chemical fertilizer usage. Therefore, this attempt is to isolate and identify different genera of straw degrading microfungi efficient in lignocellulose biodegradation. Rice straw degrading fungal species were isolated from the partially degraded rice straw collected from selected areas in Sri Lanka, following the washing and plating techniques. They were identified into the genus level using standard identification keys, and their capacity to degrade cellulose, starch, lignin, and pectin were evaluated using substrate-specific testing protocols. Eighteen fungal species in the genera of Aspergillus, Chaetomium, Cunninghamella, Goidanichiella, Penicillium, Rhizomucor, Rhizopus, Stachybotrys, and Trichoderma were isolated from the partially degraded rice straw collected from different areas of Sri Lanka. Three Trichoderma species showed significantly the highest frequency of occurrences (40%, 45%, and 43% respectively) in rice straw and a homogenous distribution among the collected samples. Furthermore, they were significantly efficient in degrading cellulose, starch, pectin, and lignin. Since the management of crop residues has become an essential aspect of sustaining long-term fertility in cropping systems, incorporation of rice straw, which is rich with cellulose, and the application of Trichoderma species into the harvested rice fields will improve the nutrient availability and hence rice yield.
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    Revealing the endophytic mycoflora in tea (Camellia sinensis) leaves in Sri Lanka: the first comprehensive study
    (Phytotaxa, 2021) Thambugala, Kasun; Daranagama, Sinushani; Kannangara, Sagarika; Kodituwakku, Shenuka
    Endophytic fungi are a diverse group of microorganisms that live asymptomatically in healthy tissues of host and they have been reported from all kinds of plant tissues such as leaves, stems, roots, flowers, and fruits. In this study, fungal endophytes associated with tea leaves (Camellia sinensis) were collected from Kandy, Kegalle, and Nuwara Eliya districts in Sri Lanka and were isolated, characterized, and identified. A total of twenty endophytic fungal isolates belonging to five genera were recovered and ITS-rDNA sequence data were used to identify them. All isolated endophytic fungal strains belong to the phylum Ascomycota and the majority of these isolates were identified as Colletotrichum species. Phyllosticta capitalensis was the most commonly found fungal endophyte in tea leaves and was recorded in all three districts where the samples were collected. This is the very first investigation on fungal endophytes associated with C. sinensis in Sri Lanka based on molecular sequence data. In addition, a comprehensive account of known endophytic fungi reported worldwide on Camellia sinensis is provided.
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    Hydrolysis of fish waste using fruit wastes of Ananas comosus and Carica papaya for the formulation of liquid fertilizers
    (International Journal of Recycling of Organic Waste in Agriculture, 2021) Ratnayake, R M C S.; Kannangara, Sagarika; Ranasinghe, Achala.
    Purpose Fish waste is a protein-rich source that can be used as a value-added product in the formulation of organic liquid fertilizers. This study carried out to investigate the utilizing potential of fruit wastes of Ananas comosus and Carica papaya that contain bromelain and papain as major proteases in order to hydrolyze fish waste proteins to fulfill plant nitrogen requirements. Method Proteases were extracted from A. comosus (leaves, crown, unripe fruit pulp, ripe fruit peels and pulp) and C. papaya (leaves, ripe fruit peels and unripe fruit peels). The optimum temperature and pH for the enzymatic activities were determined. Four liquid organic fertilizers were produced with hydrolyzed fish waste that enriched by adding Gliricidia sepium, Chromolaena odorata, Tithonia diversifolia, Mikania scandens and coconut husk-ash. Fertilizers were tested on the growth of Basella alba comparing with a standard fertilizer. Results Ananas comosus ripe fruit peels and the mixture of (A. comosus + C. papaya) showed the highest enzyme activities (0.33±0.02 and 0.36±0.01 U mL-1 enzyme respectively) at 55 oC and 70 oC. The optimum pH for all the studied extracts was 7.5 at 37 oC. The highest plant fresh and dry weights were recorded in the foliar-applied fertilizer produced by hydrolyzing the fish waste using A. comosus and C. papaya, showing no significant differences to the standard fertilizer. Conclusion Hydrolysis of fish waste using the fruit wastes of A. comosus and C. papaya could be effectively used as an organic fertilizer for the growth of B. alba that leads towards sustainable waste management.