Natural Sciences
Banana’s Large Plant Body Size an Advantage to Disease Control – Mak Scientists
Published
2 years agoon
Unlike for plants, in animals especially humans, body mass index (BMI, which is a person’s weight divided by the square of height) is a measure of physical health and pre-disposure to conditions like obesity. BMI does not make sense in plant health because of differences between plant and animal physiological systems.
However, large body size in plants may have some advantages. Apart from controlling a larger proportion of available resources and space within crowded vegetation, what other advantage does a large plant body size offer to an individual plant?
The banana’s plant body architecture
From the botanical point-of-view, the banana plant is a gigantic herb. A plant that is a herb or “herbaceous” is unable to undergo “secondary growth” and cannot form wood during its vegetative development.
The banana plant springs from an underground “true stem”, also called the “corm” or “rhizome”, to form a false stem, also called a “pseudostem” of 2-7 m height. The pseudostem is composed of the basal portions of leaf sheaths and is crowned with a rosette of 10 to 20 oblong to elliptic leaves that sometimes attain a length of 2-4 m and a breadth of 70 cm.
In mature banana plants, true stem emerges at the top of the pseudostem and bends downward to become a bunch of 10 to 300 individual fruits, or fingers, grouped in clusters, or hands, of 3 to 22. The edible part of the bunch is the female. In contrast, the inedible distal part, including the purple-colored cone-shaped end (locally known in some Ugandan dialects as “omukanaana” or “empumumpu”) constitutes the male part of the bunch.
How is the giant banana size an advantage in disease control?
A new study, titled “Xanthomonas campestris pv. musacearum Bacterial Infection Induces Organ-Specific Callose and Hydrogen Peroxide Production in Banana” and led by a team of scientists at the Department of Plant Sciences, Microbiology and Biotechnology at Makerere University in collaboration with the University of California, Davis, USA, shows how the giant banana body size can be used to control banana Xanthomonas wilt (BXW) disease.
According to Prof. Arthur Tugume, the lead scientist of this study and expert in plant pathology, when plants get infected, they respond instantly by implementing different strategies that limit the multiplication and/or mobility of the disease agents (pathogens). “For example, plants rapidly produce reactive oxygen species (ROS) such as hydrogen peroxide, superoxide ions, and hydroxyl ions. These ROS act as rapid messengers in the plant tissues to activate additional responses spreading over the entire plant body. This helps the plant’s distant tissues or organs to be aware and prepare advance defenses against the intruding pathogens”.
Prof. Dinesh-Kumar the project’s research collaborator based at the University of California-Davis, USA and expert in plant biology explains that “disease is a form of stress in plants and plants cannot perform well their biological functions when they are sick since they have to spend a lot of energy fighting against the disease. This is why disease control is important to enable plants grow well and yield high.”
The research indicates that ROS set in motion additional processes to ensure limited impact of disease and pathogens on the plant. For example, Hydrogen peroxide (H2O2), which is a ROS, has direct bactericidal, fungicidal or other anti-effects on the pathogens. Also, following H2O2 production, a unique plant carbohydrate, named “callose” starts to accumulate in large quantities within plant cells as a means of fortifying plant tissues. Callose differs from the other usual plant carbohydrates such as starch or cellulose because of the way its structures are formed.
Increased production of callose acts as a roadblock to any pathogen e.g., bacteria by limiting bacterial movement that would otherwise allow ease of attack on other tissues or cells at distant locations in the plant. “Although these plant defense responses are rapid, plant organs that are distant from the site of pathogen attack can be instrumental and block progression of bacteria or other pathogens by depositing callose in advance at strategic points” Prof. Tugume explains.
However, Prof. Tugume notes that callose participates also in many other normal developmental processes of plants, and for that reason, there is always some “housekeeping” callose in the plant tissues even without pathogenic infection. “This means that one must be able to accurately and quantitatively distinguish between ‘stress-induced’ and normal ‘housekeeping’ callose”, he adds.
How was the study done?
In this study, the researchers used young (2.5-months old) banana plantlets that had been generated from tissue culture at Kawanda Agricultural Research Institute. They then infected the plantlets with a bacterium called Xanthomonas campestris pv. musacearum (Xcm). This bacterium is the causative agent of banana Xanthomonas Wilt (BXW), the most destructive disease of bananas in East and Central Africa (ECA).
The banana leaves, pseudostems, corms and roots were analyzed for callose and compared with the control plants that had been inoculated with water instead of bacteria. H2O2 production was monitored by “DAB staining”, and by “spectrophotometry” while the analysis of callose was done by two methods: staining and visualization of callose using florescence microscopy, and using “Sandwich Enzyme-Linked Immunosorbent Assay” methods.
What did the researchers discover and how can it be used in BXW disease control?
This study revealed that the underground corm tissues assemble the stiffest resistance against BXW by depositing the highest concentrations of callose, while the pseudostem produced the highest quantities of H2O2. This is interesting for three (3) main reasons:
- Firstly, Xcm bacteria often enter through the leaves in regular plantation husbandry; hence, the corm being distant from leaves gives it an anatomical advantage in promoting the ability of lateral plants to escape Xcm infection.
- Secondly, the corm is an organ of perennation supporting vegetative and perennial continuity of the crop across seasons; hence it is charged in ensuring a disease-free next generation by severely constraining “mother-child transmission” of Xcm bacteria.
- Thirdly, the control of BXW now becomes easy when farmers are observant to the first aerial disease symptoms because Xcm is strongly constrained by bottlenecks in the pseudostem and corm.
Therefore, at the onset of aerial symptoms, diseased peudostems should immediately be removed by aseptically cutting them off at the corm without interfering with symptomless lateral shoots, which allows continuous food production and disease control to go on simultaneously. This is facilitated by the large size of the banana plant because at the onset of leaf symptoms (2.5 to 5 meters away from the corm), the bacteria have not yet arrived at the base of the pseudostem where the diseased plant can be cut off from the corm. This gives chance to a farmer to eliminate the infected pseudostems early (in 1 to 7 days) since the appearance of leaf symptoms.
This research was part of the PhD studies for Mr. Abubakar S. Mustafa at Makerere University and University of California, Davis. According to Mr. Mustafa, these discoveries make the management of BXW in banana plantations easy as long as the farmers are observant and act fast by removing diseased plants aseptically.
This study has been published by the American Phytopathological Society (APS) in an open access journal, “PhytoFrontiers”, and is freely accessible on https://apsjournals.apsnet.org/doi/full/10.1094/PHYTOFR-11-21-0073-R.
This study was funded by the Bill and Melinda Gates Foundation through the National Agricultural Research Organization (NARO), Uganda. The project had partners including the International Institute of Tropical Agriculture (IITA), the Alliance for Bioversity International and International Centre for Tropical Agriculture (CIAT) and Centre for Agriculture and Bioscience International (CABI).
For more details, contact;
Prof. Arthur Tugume
Lead Scientist
College of Natural Sciences (CoNAS)
Makerere University
Email: arthur.tugume@mak.ac.ug
Tel: +256772514841
Mr. Abubakar S. Mustafa
Co-Author and PhD student on the study
Email: mustafa.abubakar.sadik@gmail.com
Tel: +256702813233
Hasifa Kabejja
Principal Communication Officer
College of Natural Sciences (CoNAS)
Makerere University
Email: pr.cns@mak.ac.ug
Tel: +256774904211
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Natural Sciences
CARTA Fellow Anywar Appointed Member of BMC Editorial Board
Published
5 months agoon
July 5, 2024Godwin Anywar, cohort 6, Makerere University, was appointed a Member of the editorial board of BMC Complementary Medicine and Therapies on June 18, 2024. The appointment is on a rolling basis, renewable after every two years.
He also attended the Science Diplomacy Course in Trieste, Italy, from June 17 to 21, 2024, under the auspices of the American Association for the Advancement of Science (AAAS), Washington, DC, USA, and The World Academy of Sciences (TWAS), Trieste, Italy.
Source: CARTA Newsletter Issue 78
Natural Sciences
Mak Researchers develop Innovative Integrated Wetlands-bivalve system to Mitigate Effects of Pollution in Aquaculture farms in the Lake Victoria Basin
Published
5 months agoon
July 2, 2024By
Mak EditorBy Hasifa Kabejja & Dr. Robinson Odong
Overview
The fisheries sub-sector in Uganda is crucial, supporting over 5 million livelihoods and providing essential protein for up to 17 million people, with an average consumption of 10 kg per capita. Uganda’s population is projected to double in the next 27 years, prompting the National Development Plan III to aim for a significant increase in fish production, with aquaculture expected to contribute 1 million MT by 2030. The Fisheries and Aquaculture Act 2022 emphasizes adherence to National Environmental Management principles to achieve sustainable production systems.
However, as aquaculture grows, the sector faces environmental challenges due to increased intensive production and on-farm waste, including nutrients from feed, uneaten feed, poor quality feeds, pseudofeces, escaped farmed fish, and residual chemicals. These pollutants pose risks such as habitat quality deterioration, biodiversity loss, eutrophication of waterways, and the emergence of drug-resistant pathogens.
Mitigating the effects of environmental pollution from aquaculture
Through a Project titled: Mitigating the Effects of Environmental Pollution from aquaculture on freshwater resources in Lake Victoria Basin (MEEP), researchers from Makerere University in collaboration with the National Environment Management Authority (NEMA) set out to assess the effects of aquaculture facilities and practices on Lake Victoria, its catchment rivers and wetlands. The team led by Dr Ronald Semyalo from the Department of Zoology, Entomology and Fisheries Sciences (ZEFS) at Makerere University subsequently examined the effectiveness of innovative technologies, such as integrated wetland-bivalve systems, in mitigating these impacts. They also reviewed the application of national environment and aquaculture regulations in controlling environmental pollution. The study surveyed fish farms in three districts of Buikwe, Jinja, and Mukono within the Victoria Water Management Zone. Other project team members were: Dr Jerome Lugumira from NEMA, Dr Robinson Odong and Mr. Drake Ssempijja from ZEFS, Makerere University, and Ms. Ritah Namisango, Senior Public Relations Officer at Makerere. The Project was supported by the Government of Uganda through the Makerere University Research and Innovations Fund (MakRIF).
During their engagement with different stakeholders in the fishing industry including the fish farmers from Jinja, Buikwe and Mukono, as well as experts from the Directorate of Water Resources at the Ministry of Water and Environment, NEMA, and the Directorate of Aquaculture Development at MAAF, the research team established that only 138 out of 380 registered fish farms were active, with 45.6% of the farms in Jinja, 35.5% in Mukono; and 18.8% in Buikwe. Overall, over 60% of the farms were inactive posing serious environmental threats.
Dissemination of the research findings
On 26th June 2024, the project team held a workshop at Colline Hotel Mukono to disseminate the research finding to stakeholders who included fish farmers from Buikwe, Jinja and Mukono, District Fisheries Officers, as well as representatives from NEMA and MAAIF. In the presentations, the team highlighted the environmental impacts of aquaculture practices and the possibility of innovatively using nature-based, environmentally friendly innovations as a mitigation measure. The presentations covered farm characteristics, water and feed management practices, water quality assessments and waste management methods. The participants engaged in discussion on the implications of the results and shared their experiences and challenges in managing aquaculture operations.
Key findings as disseminated by the PI
Out of the 380 farms, 119 were assessed. Below are the key findings;
- Environmental Impact Assessment: It was established that 81% of the farmers had not conducted Environmental Impact Assessments (EIAs) and Environmental audits. This, the researchers noted was one of the major causes of abandoned farms.
- Farm Characteristics: The majority of farms used earthen ponds (66.9%) and were semi-intensive (63.6%), relying on manufactured feed and pond fertilization. Intensive farms (30.5%) exclusively used manufactured feeds, while extensive farms (4.2%) relied solely on pond fertilization.
- Fish Species: Nile tilapia was the top choice (96.1%) for monoculture farms, while tilapia and catfish were preferred for polyculture systems (46.9%). Intensive farms predominantly farmed Nile tilapia.
- Demographics: Most respondents were male (90.7%), with a median age of 35 years. The largest age group was 31 to 59 years (43.2%).
- Fish diseases: The research revealed a number of diseases affecting aquaculture including: lesions/wounds on the belly and cysts on the scales, skin lesions and cysts on the belly, popping eyes and white substance on fins, open skin wounds, open wounds on the head, skin lesions – greyish, swollen eyes, whitish and black patches on the skin on the pelvic fin, wounds on the head.
- Water Use: Fish farms primarily relied on spring water and lake water. Other sources, such as streams, wells, and rivers, were also utilized. In most cases, the water source was shared with the community. Only a small percentage of respondents acknowledged any known disease outbreaks on their farms. There was a strong association between the district in which the farm was located and the water source used. Majority of those using lake water were in Jinja District, while most of those using spring water were in Mukono District. Additionally, there was a significant association between the fish species cultured and the water source used.
- Feed Management: A significant proportion of the farms heavily relied on factory-made feeds. These feeds were often used in combination with farm feed materials, such as maize bran, potato vines, yam leaves, and kitchen waste. A smaller number of farmers exclusively relied on farm-made feeds, while an even smaller percentage solely relied on pond fertilization. Manufactured feeds were used in various forms: powder and floating pellets, powder, crumble, and floating pellets, powder only, floating pellets only, and sinking pellets. The most prevalent method of feed delivery was feeding by response, while some farms also practiced feeding by ration.
- Waste Management: The findings indicated a concerning lack of treatment for aquaculture effluent, with majority of respondents (69%) releasing it directly into natural streams or wetlands. This highlights the need for improved environmental management practices. Common waste sources included faecal matter and dead fish. Most farms incinerated or buried solid waste.
- Water Quality: Measurements at the representative visited farms showed compliance with FAO optimal conditions for fish farms. The physicochemical parameters of the farms visited were in line with FAO optimal conditions for fish farms.
- Prevailing Regulatory System: A comprehensive gap analysis was conducted to supplement the findings from the survey. It aimed to identify weaknesses and areas for improvement in current policies and regulations governing aquaculture. It also evaluated the effectiveness of existing measures in addressing environmental pollution, waste management, and sustainable water use. This exercise provided a foundation for developing more robust and effective regulatory frameworks that support sustainable aquaculture practices, protect water resources, and enhance the overall environmental health of the Lake Victoria basin.
Project output
***Innovative Integrated wetlands-bivalves system was developed to mitigate the impact of pollution emanating from aquaculture on the environment
Effluent from poor aquaculture practices may contain uneaten feed residues and associated components, such as suspended solids, nutrient nitrogen and phosphorus and organic materials. If discharged without any form of treatment, such effluent contributes to excessive nutrient enrichment of water bodies, a phenomenon referred to as eutrophication. Eutrophic waters have diminished ecological value, for example are low in oxygen level and can lead to fish kills. Wetland plants, such as duckweeds can aid in cleansing of aquaculture effluent of excess pollutants, through various mechanisms. For example, the plant roots adsorb suspended solids, besides offering conducive attachment surfaces for beneficial microorganisms which perform various nutrient recycling roles. The plants also uptake excess nutrients, hence reducing their levels in water. Bivalves (Molluscs) are filter feeders, hence uptake and cleanse water of detrital or solid materials, hence augmenting the roles of the plants. The integration of wetlands-bivalves system offer synergistic roles in aquaculture effluent treatment. The plants and bivalves used in the treatment can in turn be removed and used for other beneficial purposes.
Presentation on policy gaps
During the dissemination workshop, Dr Jerome Lugumira, the Natural Resources Manager, Soils and Land Use at NEMA sensitized participants on the National Environment Act, 2019 with special emphasis on policy regulations for the aquaculture sector. He emphasized the need to acquire an EIA certificate before engaging in aquaculture. Highlighting the gaps in policy, Dr Lugumira noted that Schedule 4 of the National Environment Act, 2019 does not sufficiently guide the Fisheries sector; while the Physical Planning Act, 2010 is biased towards physical development planning, and the Water Act, 1997 provides for a waste discharge permit but no consideration of the extent of wastes discharged from fish farms of varying size and intensity is provided.
He further noted that the National Environment (Wetlands, Riverbanks and Lakeshores Management) Regulations, 2000 do not guide on areas where aquaculture best fits, indicating that the application of the 25% wetland area beyond which one needs approval is vague.
Additionally, he explained that the National Environment (Waste Management) Regulations, 2020 refer to fish waste generally and not whether it means waste from fish or all waste from fish farms, such as off-cuts, unwanted materials, and that the National Environment (Standards for Discharge of Effluent into Water or Land) Regulations, 2020 consider effluent discharge and not that released in-situ and that disposed directly into water via cages and into soil via land-based systems.
Dr Lugumira called for the review of the National Environment (Wetlands, Riverbanks and Lakeshores Management) Regulations, 2000, by requiring the mandated Lead Agency (WMD) to issue approvals for access to wetlands, and appending guidance on wetlands and lake areas where aquaculture is suitable. He suggested that submissions seeking approval from NEMA should have all required approvals from MAAIF, WMD and DLGs. “The assessment process should be supported by a technical officer skilled in fisheries sciences and not generalists,” he noted.
Overview on the state of capture fisheries and aquaculture in Uganda
Sharing an overview on the state of capture fisheries and aquaculture in Uganda, Mr. Geoffrey Dheyongera, Principal Fisheries Officer at MAAIF, noted that the global decline/stagnation in capture fisheries stocks had increased demand for fish, calling for a boost in fish production through stock enhancement in water bodies and promotion of aquaculture. “There is need for huge investment in aquaculture. The Aquaculture Policy targets 1 million MT from aquaculture through establishment of aquaparks with intensive management activities.”
Key concerns raised by the farmers
During the focused group discussions, participants highlighted a number of factors undermining the growth of the aquaculture sector. These include;
- Ignorance about the laws/policy guidelines
- Low skills and lack of exposure in aquaculture management
- Low numbers of technical staff to guide the farmers
- Inexperienced technical staff
- Cheating by fish seed producers
- Expensive and poor quality feeds
- Fluctuating prices of fish
- Competition with capture fisheries/negative attitude towards farmed fish
- Increased degradation of the environment which affects water quality
- High interest rates on loans
- Farmers fear for exorbitant taxes
Proposals for improvement
- Government should recruit technical staff to assist farmers
- Thorough training of extension staff
- Encourage value addition to farmed fish
- Integrate climate smart interventions in aquaculture
- Policies regulating the sector should be popularized
- Undertake periodical review of the existing policies
- Encourage multi-stakeholder involvement in the implementation of policies
- Invest in research responsive to fish and aquaculture sector needs
- Monitor quality of fish feeds to satisfy farmers’ needs and environmental safety
- Private hatchery operators must be supported by the responsible sector agencies to ensure quality seed. Likewise, fish seed must come from certified hatcheries.
- Inspection of farms should be strengthened
- Train farmers on proper aquaculture management practices
- Farmers should work in groups to reduce production costs, negotiate better prices for their products, access credit facilities and maximize profits
Remarks by the Guest of Honour, Mukono District CAO, and the Principal, CoNAS
In his remarks, the Guest of Honour, also Assistant Commissioner Aquaculture Management at MAAIF, Mr. Alio Andrew, guided the farmers on proper aquaculture practices, and encouraged Ugandans to invest in the fish sector. “The demand for fish has increased. Aquaculture remains a viable option,” he noted. He also raised the need to support private hatchery operators to produce quality seed, emphasizing that fish seed should only be bought from certified hatcheries. He highlighted the significance of biosecurity in aquaculture, and the need to collect appropriate data on the sector.
The CAO Mukono District called for intensified training of farmers in aquaculture management practices. She advised the farmers to work in groups if they are to make reasonable profits.
The Principal, College of Natural Sciences (CoNAS), Makerere University, Prof. Winston Tumps Ireeta, acknowledged the involvement of the community in research, and appreciated the fish farmers for actively participating in the project activities. He expressed gratitude to the Government of Uganda for the continued support towards research at Makerere University. Besides other initiatives geared towards improving research at Makerere, the Government is supporting over 700 research projects at Makerere through the Research and Innovations Fund. He also appreciated MAAIF and NEMA for the technical guidance extended towards the project.
Natural Sciences
Call For Applications For Masters Scholarship Under The Biosorption For Sustainable Small-Scale Gold Mining In Uganda (BioGold) Project
Published
6 months agoon
June 5, 2024BioGold Project is a three-year collaborative project among five academic institutions including, Kyambogo University, Makerere University, Gulu University, University of Pretoria and University of Continuing Education, Krems, Austria funded by the Austrian Development Cooperation under the APPEAR Partnership. The project will combine principles of biosorption and chemical remediation to treat contaminated wastewater, tailings, rehabilitate contaminated soils so as to protect vulnerable ecosystems surrounding artisanal gold mining (ASGM) areas in Uganda. This study will design biochar composites from locally available biomass to enhance mercury removal from wastewater and tailings as well as rehabilitate mercury-contaminated soils making them fit for agriculture. The project envisages to train and build capacity of young researchers in Uganda. As such the project has been allocated an MSc. position under Component II, to support to full-time student to undertake studies in Austria. The successful MSc candidate is expected to undertake research on characterizing, optimizing biochar and modify the biochar to improve the sorption capacities.
The project consortium is now inviting qualified and interested persons to apply for nomination for the award of the scholarship. The project has strong preference for female candidates, therefore strongly encouraged to apply.
Eligibility criteria
In addition to APPEAR requirements https://appear.at/en/implementation/embedded-scholarship-application, the applicants should:
- Not be older than 30 years (women not older than 35)
- Demonstrate interest and capability to work in the priority themes
- Present a concept note to provide understanding of the subject
- Have a minimum of second- upper class bachelor’s degree in any of the following programmes: BSc in Chemistry, BSc in Environmental Science, & BSc in Environmental Engineering
Benefits
The successful applicants will receive a full scholarship (up to 24 months) which includes;
- Return air ticket and visa costs to Austria
- Monthly stipend of €1000 while in Austria to cater for personal welfare, accommodation and local movement
- Research related expenses.
Application process
- A complete application form
- A one-page motivation letter
- Curriculum vitae (maximum 2 pages)
- A completed Master Scholarship Application Form for Embedded APPEAR Projects
- Copies of Academic documents
- Photocopy of the passport and/or ID
- Recommendation letters from two academic referees.
- All applications must be sent electronically to Dr. Mary Kaggwa (marykaggwa@kyu.ac.ug) and copied to Dr. Peter Akoll (peter.akoll@mak.ac.ug) and Dr. Denis Nono (d.nono@gu.ac.ug) not later than 5.00pm East African Time on 20th June 2024.
Members of staff with former students interested in biochar technology and its use in heavy metal removal are requested to share the advert with them.
Full Advert and Application form may be accessed below.
Note: Only successful applicants will be contacted.
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