Accidental ingestion of soil is a significant pathway for lead (Pb) exposure, although it is secondary to soil-plant transfer and thus receives less focus in risk assessments. Measuring total, Mehlich 3-extractable, and bioaccessible Pb in routine soil tests could enhance risk evaluation related to the consumption of contaminated soils. This study examined Pb bioaccessibility in soils used for long-term vegetable cultivation across two cropping systems and soil types in three Sri Lankan agro-climatic zones. A physiologically based in vitro extraction test (PBET) at pH 2 and 2.5 estimated human Pb exposure through soil ingestion. The research also evaluated whether Mehlich 3 extractable Pb could reliably indicate both bioaccessible and total Pb levels. Surface soil samples (0–15 cm) were collected from: vegetable-only cropping system on Ultisols in Nuwara Eliya (n = 46), vegetable-paddy rotation on Ultisols in Badulla (n = 54), and intensive vegetable cropping system on Entisols in Kalpitiya (n = 48). Concentrations of bioaccessible, total, and Mehlich 3 extractable Pb were measured. Bioaccessible Pb in soils from Nuwara Eliya, Badulla, and Kalpitiya ranged from 01 to 2.8, 0.1-8.0, and 03–8 mg/kg, respectively, representing 0.04-35
Tea, from Camellia sinensis, is second only to water in global consumption. Tea germplasm in Sri Lanka consists of over 600 tea cultivars, and currently, 70 of them are recommended for commercial tea cultivation. However, the biological activities of Sri Lankan tea cultivars have not been documented. The present study investigated the in vitro enzyme inhibitory activities, viz., lipase, α-amylase, xanthine oxidase, α-glucosidase, and acetylcholinesterase, as well as antioxidant activity in black tea and tea leaves harvested from 15 different tea cultivars during the major seasons in Sri Lanka. The remarkable α-glucosidase, xanthine oxidase, and acetylcholinesterase inhibitory activities in black tea and tea leaves of tea cultivars were observed, with the IC50 of black tea ranging from 5.77 to 104.10 ppm, 0.55 to 36.75 ppm, and 28.37 to 184.06 ppm, respectively. Additionally, some tea cultivars have exhibited moderate α-amylase and lipase inhibitory activities. The radical scavenging activities of DPPH (1,1-diphenyl-2-picrylhydrazyl) and nitric oxide on black tea and tea leaves were exhibited with the IC50 of black tea ranging from 14.03–67.23 ppm and 76.22 to 251.35 ppm, respectively.
Purple tea, produced from harvestable shoots of Camellia sinensis, which is a specialty tea, has shown a growing interest in the consumer market and is slowly gaining recognition in many countries. The objective of the study was to evaluate the potential of tea genetic resources from Sri Lanka for the production of purple tea for the first time. Tea anthocyanins, including pelargonidin, delphinidin, malvidin, and cyanidin, were quantified using high-performance liquid chromatography(HPLC) following acid hydrolysis. The quantification of anthocyanidins was carried out in fresh tea leaves and in purple tea of the five tea cultivars. The results revealed that delphinidin and cyanidin were detected in all five tea cultivars, and malvidin was not detected in any of the five tea cultivars; however, pelargonidin was detected only in TRI 26 and TRI 2043 tea cultivars. The highest anthocyanidin content, which was 0.847 mg/g, was recorded in the fresh tea leaves of the TRI 5006 tea cultivar, and the lowest anthocyanidin concentration was detected in the fresh tea leaves of the TRI 3055 tea cultivar, which was 0.044 mg/g. Malvidin was not detected in the tested tea cultivars; further research on additional tea cultivars is required to confirm this. In addition, the contents of caffeine, gallic acid, catechins, and total polyphenols were also determined. According to the results, TRI 5006, TRI 26, and TRI 2043 tea cultivars could be utilized as potential tea cultivars for purple tea production in consideration of their higher anthocyanidin content and polyphenolic profiles.
Most pestalotioid species are phytopathogens characterized by conidia with appendages and can also function as endophytes and saprobes. During a morpho-molecular study of plant-inhabiting micro-fungi in Sri Lanka, two pestalotioid species were isolated from the lesions of living leaves of Garcinia mangostana and Annona muricata. Maximum Likelihood and Bayesian Inference analyses of combined internal transcribed spacers (ITS), β-tubulin (tub2), and translation elongation factor 1-α (tef1-α) sequence data were used to determine the phylogenetic affinities of the collected species. Detailed morphological and multi-locus phylogenetic analyses further validated that the collected pestalotioid species belonged to Neopestalotiopsis. Neopestalotiopsis cubana (GMBUCC 24–001) and N. scalabiensis (GMBUCC 24–002 and GMBUCC 24–003) were identified as associated with the fresh leaves of G. mangostana and A. muricata, respectively. This is the first record of the Neopestalotiopsis species associated with these hosts worldwide. This study evaluated the in vitro biocontrol potential of Trichoderma atroviride (GMBUCC 24–014) and Daldinia eschscholtzii (UKBC 036) against Neopestalotiopsis cubana and N. scalabiensis, resulting in significant biocontrol potential of T. atroviride (GMBUCC 24–014) against both species than D. eschscholtzii (UKBC 036). Accurate identification of pestalotioid species is crucial for developing effective biocontrol methods to manage diseases and enhance economic development.
Exobasidium vexans is an important tropical phytopathogenic fungus that causes blister blight in tea. Despite its devastating impact on tea cultivation, this pathogen remains poorly studied. In this study, fresh symptomatic leaf samples of blister blight were collected from the main tea-growing regions of Sri Lanka and from Northeast and Eastern India, where the disease was originally reported. Fresh collections obtained from each locality were characterized based on micromorphological characters and molecular data and an epitype was designated. A molecular phylogeny based on the ITS (ribosomal nuclear internal transcribed spacer 1, 5.8S, internal transcribed spacer 2), 28S rDNA (largest subunit of ribosomal gene partial sequence), and TEF-1α (translation elongation factor-1 alpha) revealed that E. vexans collections represent a monophyletic clade closely related to E. reticulatum. This study provides crucial insights into the phylogenetic position and genetic diversity of E. vexans, offering a foundation for future studies on its biology, epidemiology, and management to mitigate impact on global tea production.
