
Adash RamsubhagUniversity of the West Indies, St. Augustine | UWI · Department of Life Sciences
Adash Ramsubhag
BSc, PhD
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123
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Introduction
Skills and Expertise
Additional affiliations
March 2001 - present
Education
July 1992 - August 1997
Publications
Publications (123)
Extensive pesticide use in Trinidad and Tobago (T&T) raises concerns for human and environmental health. Therefore, this study sought to assess the general knowledge, attitudes and practices of T&T residents on pesticides and related topics. Using convenience (non-probability) sampling, a questionnaire was administered to residents of Trinidad (N =...
Seaweed extracts have emerged as significant biostimulants in modern agriculture, demonstrating notable benefits in enhancing plant growth and development. Furthermore, hydroponically cultivated crops treated with biostimulants have exhibited higher growth and productivity compared to soil-based systems. Despite the recognized advantages of seaweed...
Several environmental and economic issues have been brought about by mass accumulations of Sargassum along the coastlines in Trinidad and Tobago, and the wider Caribbean region. Though there are massive environmental issues associated with this seaweed biomass, there is also a chance to make innovations, thereby making this problem into a solution....
Copper resistance in phytopathogens is a major challenge to crop production globally and is known to be driven by excessive use of copper-based pesticides. However, recent studies have shown co-selection of multiple heavy metal and antibiotic resistance genes in bacteria exposed to heavy metal and xenobiotics, which may impact the epidemiology of p...
Multi-trait efficiency and interactivity of bacterial consortia used to enhance plant performance under water stress conditions
Keywords:
ACC-deaminase; Indole-3-acetic acid; Rhizobacteria; Biofilm Water-stress
A B S T R A C T
Water stress is a major limiting factor for agricultural production under current and projected climate change scenarios....
Background
Copper-induced gene expression in Xanthomonas campestris pv. campestris (Xcc) is typically evaluated using targeted approaches involving qPCR. The global response to copper stress in Xcc and resistance to metal induced damage is not well understood. However, homologs of heavy metal efflux genes from the related Stenotrophomonas genus are...
Background: Haemagogus janthinomys is a primary sylvan vector of yellow fever virus and the emerging Mayaro virus. However, despite its medical importance, there is a dearth of data on the molecular taxonomy of this mosquito species. Methods: In this study, DNA barcoding analysis was performed on 64 adult female mosquitoes from Trinidad morphologic...
Abiotic stress, especially drought, is one of the principal constraints of crop productivity and is expected to worsen with climate change in the near future. This warrants the development of new technologies to decrease the impact of drought on crop productivity. Biostimulants made from seaweed extracts are one of the relatively new biological bas...
[This corrects the article DOI: 10.1371/journal.pgph.0001455.].
This research captures the molecular changes in bell pepper when foliar treated with locally prepared seaweed extracts.
Abiotic stress, especially drought stress, is one of the principal constraints of crop productivity and is expected to worsen with climate change in the near future. This warrants the development of new technologies to decrease the impact of drought on crop productivity. Biostimulants made from seaweed extracts are one of the relatively new biologi...
Klebsiella pneumoniae and Klebsiella quasipneumoniae are closely related human pathogens of global concern. The more recently described K. quasipneumoniae shares similar morphological characteristics with K. pneumoniae and is commonly misidentified as this species using traditional laboratory techniques. The vast mobilome in these pathogenic bacter...
Background
There has been limited exploration of copLAB genotypes and associated copper resistance phenotypes in Xanthomonas spp. in the southern Caribbean region. An earlier study highlighted a variant copLAB gene cluster found in one Trinidadian Xanthomonas campestris pv. campestris (Xcc) strain (BrA1), with <90% similarity to previously reported...
The COVID-19 pandemic highlighted the importance of global genomic surveillance to monitor the emergence and spread of SARS-CoV-2 variants and inform public health decision-making. Until December 2020 there was minimal capacity for viral genomic surveillance in most Caribbean countries. To overcome this constraint, the COVID-19: Infectious disease...
The efficacy of alkaline extracts from Acanthophora spicifera, Gracilaria ornata, Codium taylorii, Caulerpa serrulata, and Sargassum vulgare was assessed both in vitro and in planta under greenhouse conditions. Seaweeds were collected from the coast of Trinidad, WI. Alkaline extracts were tested for their efficacy in promoting plant growth and perf...
This study investigated the sources and microbiological quality of domestic water used by rural communities of Speightstown, Barbados; Carriacou, Grenada; and Nariva, Trinidad. The primary water source was harvested rainwater in Carriacou, and the public water supply for Nariva and Speightstown. Secondary water supplies of the communities came from...
The burdens associated with acute gastroenteritis involve billions of dollars in expenses, coupled with significant morbidity and mortality globally. To reduce these burdens, health officials and policymakers require up-to-date data (health and economic) to request and allocate resources in guiding the development and implementation of preventative...
Seaweed extracts (SWEs) are becoming integrated into crop production systems due to their multiple beneficial effects including growth promotion and induction of defence mechanisms. However, the comprehensive molecular mechanisms of these effects are yet to be elucidated. The current study investigated the transcriptomic changes induced by SWEs der...
The use of seaweed extracts (SWEs) in crop production is becoming a viable and sustainable agronomic practice due to its multiple benefits to crops and the environment. However, no studies have documented the effect of foliar SWEs applications on the plant microbiota. Here we used foliar applications of Sargassum vulgare, Acanthophora spicifera, an...
Accurate species identification and antibiotic resistance profiling are essential for the effective management of infections caused by bacterial pathogens. In this study, 373 clinical isolates of K. pneumoniae from major hospitals in Trinidad, West Indies, were characterized for resistance against beta-lactam antibiotics and the presence of genes e...
In 2009, the burden of illness study for acute gastroenteritis in Trinidad and Tobago highlighted that ~10% of stool samples tested were positive for a foodborne pathogen. The study also noted that limited laboratory screening for pathogens contributed to a lack of etiology as public health hospitals only routinely tested for Salmonella and Shigell...
Water quality is a growing concern throughout the developing world and the effects of water pollution can be both harmful and costly. Increasing levels of fecal pollution and associated waterborne pathogens pose a potential economic constraint and hardship for Caribbean islands as their economies primarily depend on a thriving coastal tourism indus...
Extracts of Ascophyllum nodosum are commonly used as commercial biostimulants in crop production. To further understand the seaweed extract-induced phenomena in plants, a transcriptomic study was conducted. RNA-seq differential gene expression analysis of tomato plants treated with a commercial A. nodosum extract formulation (Stimplex) revealed the...
Comparative genomics of the black rot pathogen Xanthomonas campestris pv. campestris and non-pathogenic co-inhabitant Xanthomonas melonis from Trinidad reveal unique pathogenicity determinants and secretion system profiles ABSTRACT Black-rot disease caused by the phytopathogen Xanthomonas campestris pv. campestris (Xcc) continues to have considerab...
Latin America and the Caribbean islands have a very high incidence rate and diversity of begomoviruses transmitted by the whitefly, Bemisia tabaci. More than 12 species of economically important crops, in addition to several major weeds, have been reported to be infected by these viruses, with an increasing trend in the rates of infections in this...
The Caribbean region experiences significant water supply challenges, especially for 30% of the population who live in rural areas. Improved water resource management in this region would enhance water availability for its population, but this requires reliable quantitative data to guide relevant policy decisions. The Water Poverty Index (WPI) and...
The effects of a commercial Ascophyllum seaweed extract (ASWE) on the growth parameters of sweet pepper plants were studied under grow box home garden conditions in the Caribbean. Grow box cultivation of vegetables in the backyard is very popular in Trinidad and Tobago and the wider Caribbean region. The use of synthetic chemicals should be avoided...
Currently, there are increasing concerns about the possibility of a new epidemic due to emerging reports of Mayaro virus (MAYV) fever outbreaks in areas of South and Central America. Haemagogus mosquitoes, the primary sylvan vectors of MAYV are poorly characterized and a better understanding of the mosquito’s viral transmission dynamics and interac...
Zucchini yellow mosaic virus (ZYMV) is a member of the genus Potyvirus that is becoming a serious pathogen of pumpkin and other cucurbits in Trinidad and Tobago and the entire Caribbean region. In this study, four ZYMV isolates infecting pumpkin in Trinidad and Tobago were characterized by complete genome sequencing. Phylogenetic analysis showed 5....
Currently, there are increasing concerns about the possibility of a new epidemic due to emerging reports of Mayaro virus (MAYV) fever outbreaks in areas of South and Central America. Haemagogus mosquitoes, the primary sylvan vectors of MAYV are poorly characterized and a better understanding of the mosquito’s viral transmission dynamics and interac...
The use of seaweed-based bioproducts has been gaining momentum in crop production systems owing to their unique bioactive components and effects. They have phytostimulatory properties that result in increased plant growth and yield parameters in several important crop plants. They have phytoelicitor activity as their components evoke defense respon...
Zucchini yellow mosaic virus is a potyvirus , which is becoming a serious pathogen of pumpkin and other cucurbits in Trinidad and Tobago and the entire Caribbean region. In this study, four Zucchini yellow mosaic virus (ZYMV) isolates infecting pumpkin in Trinidad and Tobago were characterized by complete genome sequencing for the first time. Phylo...
The phytoelicitor and phytostimulatory properties of alkaline extracts of two tropical seaweeds, Sargassum vulgare C. Agardh and Acanthophora spicifera (M.Vahl) Børgesen, collected from the coasts of Trinidad were investigated in tomato and sweet pepper crops. Foliar applications of seaweed extracts (SWE), at 0.5% concentration, resulted in substan...
Liquid extracts of several seaweeds possess great potential as biostimulants for use in agricultural plants. Numerous studies have provided evidence of improved growth and yield parameters in crop plants treated with seaweed extracts. Still, there is a shortage of information available on the mechanisms of action of these extracts on plant growth p...
The natural variation of multiple abiotic stresses in hyper-seasonal edaphic savanna provides a unique opportunity to study the rhizobacteriome community structure of plants adapted to climate change-like conditions in the humid tropics. In this study, we evaluated changes in soil, plant and rhizobacteriome community structure parameters across sea...
In this study, we report the first isolation of three antibiotic indole alkaloid compounds from a Pseudomonad bacterium, Pseudomonas aeruginosa UWI-1. The bacterium was batch fermented in a modified Luria Broth medium and compounds were solvent extracted and isolated by bioassay-guided fractionation. The three compounds were identified as (1) tris(...
The aim of this study was to identify the main sources of fecal pollution at popular beaches and rivers in the island of Trinidad. Escherichia coli enumeration and microbial source tracking (MST) were used to identify the primary sources of fecal bacteria contamination at the sites. Nineteen sites exceeded USEPA water quality standards for safe rec...
Abstract: The soils adjacent to the La Brea Pitch Lake in Trinidadare expected to have high levels of Polycyclic Aromatic Hydrocarbons (PAHs) and PAH-degrading bacteria. This is due to the historical influx of hydrocarbons (bitumen) since the Cretaceous period. The PAHs are toxic, carcinogenic and genotoxic compounds which are natural components fo...
ABSTRACT
The Mayaro virus disease (MAYVD) is an emerging mosquito borne zoonosis that was first reported on the island of Trinidad in 1954. The viral agent for this disease is known to presently be endemic to Central and South America. The enzootic cycle of the Mayaro virus (MAYV) is not fully characterized, though primates are thought to be the mai...
A study was conducted to isolate and evaluate the hydrocarbon-degrading potential of indigenous fungi in consortia from natural petroleum seepages in Trinidad. Sixty-seven isolates were obtained from two seepages using medium containing four single hydrocarbon fractions: diesel, naphthalene, pyrene, and asphaltene. The majority of the isolates belo...
The biocontrol potential of a new Burkholderia sp strain-V-1 was evaluated under laboratory and greenhouse conditions. Tomato seeds, when treated with the bacterial suspension, showed significant increase in germination percentage, root and shoot length and seedling vigour. The Burkholderia sp strain-V-1 inhibited the mycelial growth of Pythium aph...
This study evaluated the effectiveness of a commercially available Ascophyllum nodosum alkaline extract as a plant growth stimulant and defense elicitor against foliar diseases of tomato and sweet pepper caused by Xanthomonas campestris pv. vesicatoria and Alternaria solani in a tropical environment. Foliar applications of 0.5% A. nodosum extract (...
Pumpkin is an important food crop of the Caribbean region, however, in recent years, the crop has been afflicted by many bacterial, fungal and viral infections. Diseases afflicting pumpkins mainly affect foliage, vines and fruits. A three-year survey during 2014-2017 and a monitoring programme of pumpkin diseases were carried out at several locatio...
Vegetable production plays a vital role in food security by providing nutritional supplements. Insect-transmitted plant viruses are a major constraint to production of many important vegetable crops. Most plant viruses depend on vectors for their survival and spread. The vectors of plant viruses are largely sucking insects such as aphids, whiteflie...
Cultivation of tomatoes in Caribbean region are affected by many bacterial, fungal and virus infections causing reduction in crop yield and quality of the fruits. Current disease management practises rely heavily on chemical usage, which usually exceeds recommended levels specified by environmental protection and food safety agencies. Integrated di...
Pumpkin fields in Trinidad have been noted to become increasingly afflicted by gummy stem blight. This disease is caused by Didymella bryoniae which is known to target most cucurbit crops. Symptoms can occur on either the leaf, stem and or fruit of the plants, as drying of plants leading to premature death and significantly decreased yields of the...
Field surveys conducted during 2014-2016 in farmers' fields in Trinidad (T&T), identified tomato plants showing severe symptoms of stunting, upward curling of leaves and reduction of leaf size. These symptoms were suspected to be indicative of the infection byTomato yellow leaf curl virus (TYLCV). Leaf samples from 100 symptomatic plants were colle...
Tomato is an important vegetable crop in the Caribbean region but is affected by many bacterial, fungal and viral diseases which have contributed to serious yield losses in recent years. The Plant-Microbe research team of DLS, UWI-STA, conducted extensive survey during the period of 2014-2016, in some Caribbean islands including, Grenada, St. Lucia...
Symptoms of severe mosaic and yellowing of leaves and severe deformation of pumpkin fruits have been noticed in field plants throughout Trinidad during recent years. Severe mosaic symptoms are normally associated with multiple virus infections which is nearly impossible to diagnose. In order to molecularly identify the viruses, RNAs were extracted...
Crop management and plant protection methods adopted by farmers in various regions of Trinidad, Trinidad and Tobago were investigated. A sample survey was conducted for growers selected from 11 locations in Trinidad representing various agriculturall zones. Questionnaires containing both open-ended and closed-ended questions were included and 31 fa...
Salt stress is a major concern and a limiting factor to proper seed germination and healthy plant establishment which ultimately affects crop production. Macroalgae such as Ascophyllum nodosum have been shown to possess several bioactive compounds which when applied in a usable form can mitigate plant stresses such as salinity stress. The current s...
Proper diagnosis is critical for effective management of plant diseases. Traditional microscopic and culture-based techniques generally require a long time for completion, are often subjective and cannot resolve identity of pathogens at low levels of taxa. Methods based on serology, analysis of fatty acids and carbon utilization profiles are also a...
Proper diagnosis is critical for effective management of plant diseases. Traditional microscopic and culture-based techniques generally require a long time for completion, are often subjective and cannot resolve identity of pathogens at low levels of taxa. Methods based on serology, analysis of fatty acids and carbon utilization profiles are also a...
Six cholic acid derivatives (1 - 6) were isolated from broth cultures of
Bacillus amyloliquefaciens UWI-W23, an isolate from the Trinidad Pitch Lake. The compounds were extracted via solvent extraction and/or XAD resin adsorption and purified using silica gel column chromatography. Their structures were elucidated using 1D, 2D NMR and ESI-MS spectr...
Seaweed extracts are commonly used as phytoelicitors to promote crop growth and yield, worldwide. However, extracts of some seaweed species are known to induce defence processes in plants and may have potential for use as plant protection agents in the management of crop diseases. Most of the research on seaweed extracts as elicitors of plant defen...
Cowpea (Vigna unguiculata) is an important agricultural food crop of Trinidad and Tobago and the southern Caribbean region. According to the FAO (http://faostat.fao.org), the area harvested in 2014 was approximately 154 ha, and production was around 499 t. An extensive survey of farmers’ cowpea fields throughout Trinidad carried out in 2016 reveale...
Whole genome sequencing of a copper resistant (CuR) black rot strain of Xanthomonas campestris pv. campestris (Xcc) isolated from a broccoli plant in Trinidad revealed a unique operon for copper resistance. The cop genes of strain Xcc-BrA1 were determined to be present on a 160 to 180 kb plasmid shown to be non-conjugative with other xanthomonads....
Ectotherms depend on the environmental temperature for thermoregulation and exploit thermal regimes that optimise physiological functioning. They may also frequent warmer conditions to up-regulate their immune response against parasite infection and/or impede parasite development. This adaptive response, known as ‘behavioural fever’, has been docum...
With increasing problems of decreased efficacy, toxicity and environmental degradation due to the use of chemical fungicides, there is urgent need for developing alternative strategies for managing crop diseases. One approach currently being explored is the application of safe organic-based compounds to prime the defence systems of plants in order...
Tomato is one of the most important agricultural crops in Trinidad and Tobago, with an annual fruit production of ∼1,500 tonnes (http://faostat.fao.org). Over the past two years (2014 to 2016), several farmers’ fields planted with tomato in Trinidad were showing noticeable symptoms, such as severe stunting, upward curling of leaves, and reduction o...
The effect of Ascophyllum nodosum (brown seaweed) extract (ANE) application on diseases of field tomatoes was studied in the field and greenhouse under tropical conditions in Trinidad, West-Indies. Different methods of applications of ANE (foliar spray/+ root-drench, spray alternated with fungicides) and ANE concentrations (0.2% and 0.5%) were eval...
This book contains 19 chapters focusing on crop disease management by using natural compounds derived from plants, marine organisms and microbes. Some alternative and ecologically friendly approaches for plant diseases control are also presented.
Tomato plants (Lycopersicum esculentum Mill) grown under tropical field conditions were treated with an alkaline seaweed extract made from Ascophyllum nodosum (ASWE). Two field experiments and one greenhouse experiment were conducted to evaluate methods of application, dosage of application, and the impact of each on plant growth parameters and on...
Clostridium difficile is a Gram positive rod-shaped bacterium that produces two major toxins, A and B. The detection of the organism and its toxins has been widely carried out using specialized Enzyme-Linked Immunosorbent Assay (ELISA) kits; however these generally have been unsuccessful in identifying all Clostridium difficile positive samples. In...
A total of 480 samples of locally produced processed meats, including chicken franks, chicken bologna, and bacon from brands A and B, was collected from 8 supermarkets across the island of Trinidad over a 1-year period and subjected to a range of microbiological analyses. The results showed that 54.2, 0.4, and 1.7% of the samples exceeded recommend...
Marine macrophytes have been recently recognized as promising sources of bioactive molecules and as such many drugs leads have arisen from them. We investigated the antibacterial activity of methanol extracts of seaweeds against several human pathogens. Among the seaweeds screened,
three species showed inhibitory effects against at least one pathog...