Botany

Anthracnose of grapevines in Sri Lanka: Pathogen identification, epidemiological insights, and in vitro evaluation of bioactive extracts

2025-01-01T00:00:00Z

Anthracnose of grapevines in Sri Lanka: Pathogen identification, epidemiological insights, and in vitro evaluation of bioactive extracts Sureshkumar, D.; Emmanuel, C.J.; De Costa, D.M. Anthracnose disease of grapevines, historically attributed to Elsinoe ampelina, has emerged as a significant concern in the Jaffna Peninsula, Sri Lanka. This study aimed to characterize the disease’s etiology, epidemiology, and potential for biological control. Field assessments over two cultivation seasons (2022–2023) revealed a consistent pattern of disease progression, with peak incidence and severity occurring between 40 and 60 days post-pruning. Rainfall positively correlated with disease metrics, while wind speed showed a suppressive effect. Morphological and cultural characterization of 54 fungal isolates, coupled with multilocus phylogenetic analysis (ITS, actin, and histone H3), confirmed the presence of two distinct Colletotrichum morphotypes within the C. gloeosporioides species complex, potentially representing a novel lineage. Pathogenicity assays verified the virulence of representative isolates on grape leaves and fruits under both in vitro and in planta conditions. Furthermore, spore germination and lesion development were significantly inhibited by cell-free suspensions from Pseudomonas fluorescens, Bacillus megaterium, and ethanol extracts of Azadirachta indica, Lantana camara, Vitex negundo, Stoechospermum marginatum, and Padina boryana. These findings establish a members of new lineage of C. gloeosporioides complex as the primary causal agent of grape anthracnose in the region and highlight the promise of integrating biocontrol agents and botanical extracts into sustainable disease management programs.

Comparative Analysis of Qualitative and Quantitative Phytochemical Evaluation of Selected Leaves of Medicinal Plants in Jaffna, Sri Lanka

2022-01-01T00:00:00Z

Comparative Analysis of Qualitative and Quantitative Phytochemical Evaluation of Selected Leaves of Medicinal Plants in Jaffna, Sri Lanka Rajkumar, G.; Panambara, P.A.H.R.; Vinotha, S. The traditional system of medicine in Sri Lanka has shown much better improvement, has fewer side effects, and is less expensive than modern synthetic drugs in the treatment of many diseases. The objective of the present study was to comparatively evaluate the qualitative and quantitative analysis of phytochemical constituents of leaves of Murraya koenigii (L.) Spreng., Tinospora cordifolia (Wild) Hook.f., Enicostemma axillare (Lam) A. Raynal, and Gymnema sylvestre R. Br. were collected from Jaffna District. The shade-dried leaves were powdered and extracted with ethanol using the cold extraction technique. These ethanolic extracts were subjected to phytochemical analysis using recommended laboratory techniques. The one-way analysis of variance (ANOVA) and Tukey's multiple comparisons at probability value (p <0.05) were used in the statistical analysis of the data. Phytochemical screening showed the presence of alkaloids, flavonoids, tannins, terpenoids, steroids, saponins, phenols, and glycosides. Murraya koenigii shows the highest phenol and alkaloid contents (1960.71±66.88 and 19.42±0.26). Enicostemma axillare shows the highest flavonoid and tannin contents (22.27±0.86 and 1.26±0.017). Therefore, E. axillare and M. koenigii can be used as nutraceuticals in traditional medicine.

A Comparison of the Antimicrobial Activity of Various Parts of Syzygium cumini (L.) Skeels in Jaffna District, Sri Lanka

2024-01-01T00:00:00Z

A Comparison of the Antimicrobial Activity of Various Parts of Syzygium cumini (L.) Skeels in Jaffna District, Sri Lanka Vethanayakan, K.; Rajkumar, G.; Vinotha, S. In recent years, there has been interest in researching and developing new antibiotics from various sources to fight microbial infections. Antibacterial properties are found in numerous medicinal plants that can prevent the growth and virulency of different microbes during infections. Thus, there is a great deal of attention given to examining antimicrobial activity of herbal material and its evaluating methods. Syzygium cumini L. Skeels is an important medicinal plant which grows in the Jaffna district. In its various parts, there are numerous phytochemical compounds that have multiple pharmacological effects such as hypoglycemic, diuretics, analgesic, anti-inflammatory, antioxidant, and gastro-protective effects. The main objective of this study was to investigate the antimicrobial effect of ethanolic, methanolic, and aqueous extracts of different parts of S. cumini plant. The agar well diffusion method was used to analyze antibacterial activity against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa while the standard disk diffusion method was used for the in-vitro antifungal activity against Mucor sp., Aspergillus sp., and Fusarium sp. Based on the antibacterial activity results, it was found that the ethanolic seed coat extract had the largest inhibition zone diameter against S. aureus (27.56±0.46 mm) while the aqueous extract of bark showed the lowest inhibition zone against Pseudomonas sp. (11.50±0.66 mm). Based on the antifungal activity results, it was revealed that the methanolic extract of the leaf had the lowest diameter of inhibition of fungal growth against Fusarium sp. (15.87±0.73 mm) while the aqueous extract of bark showed the highest diameter of inhibition against Aspergillus sp. (37.93±0.80 mm). The study found that the ethanolic seed coat and methanolic leaf extracts had greater antibacterial and anti-fungal activities than the other extracts obtained from the plant. In the future, drug leads may be generated for treating infectious diseases caused by microbes using the seed coat and leaves of S. cumini plant.

Microbiological Parameters of Different Waste Waters to Evaluate Their Potential to be Use as a Media for Chlorella sp. and Spirogyra sp. Cultivation

2022-01-01T00:00:00Z

Microbiological Parameters of Different Waste Waters to Evaluate Their Potential to be Use as a Media for Chlorella sp. and Spirogyra sp. Cultivation Lancy, D.; Thavaranjit, A.C.; Rajkumar, G. Globally there is severe water scarcity, and methods to reuse wastewater need to be adapted. The objective of this research was to determine the microbiological parameters of different wastewaters in order to study the potential of wastewater as a media to cultivate algae. Food, agriculture, drainage and municipal wastewater sample were collected in sterile bottles separately. Aerobic, anaerobic plate counts, yeast and mold counts were evaluated. Enumeration of coliform, fecal coliform, coliphages and microalgae was performed with all wastewater samples. Chlorella sp. and Spirogyra sp. were isolated from three different paddy field water samples, and growth studies were carried out in different wastewater media with standard sterile Chu’s medium and in sterile tap water medium as control. Heterotrophic, anaerobic bacteria, microalgae, yeast and molds were found in all types of wastewater. Agriculture wastewater had the highest value for aerobic, anaerobic, yeast and mold count in the highest dilution. Coliforms and fecal coliforms were absent in food and agriculture wastewaters on Eosin Methylene Blue (EMB) medium. Coliform and Fecal coliforms were only observed in drainage and municipal wastewater on Endo agar (EA) medium. Coliphages were absent only in agricultural wastewater and found in the highest numbers in municipal wastewater. Except for agricultural wastewater, other three types of wastewaters contain microbial contaminations. Agriculture wastewater medium significantly enhanced the growth of Chlorella sp. than the standard Chu’s medium. The growth of Spirogyra sp. was stimulated by the food wastewater medium than the other media.