Natural Sciences
Banana’s Large Plant Body Size an Advantage to Disease Control – Mak Scientists
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
Newly admitted students to the College of Natural Sciences (CoNAS) have been strongly encouraged to make academic excellence their top priority as they begin their university journey. During the official College orientation held on 6th August 2025, continuing students shared valuable insights aimed at helping the freshers adapt and thrive both academically and socially in the university environment.
Speaking at the event, Ms. Britah Kemigisha and Mr. Leakey Mbabazi, students of Conservation Biology and Petroleum Geosciences respectively, offered practical advice drawn from their experiences at CoNAS. The two students emphasized the importance of time management, consistent class attendance, and fostering healthy academic competition.
“Be ambitious and attend classes because attendance earns you some marks. Be competitive in a way that promotes excellence,” Mbabazi advised. He encouraged freshers to approach university life with purpose, noting that unlike in high school, university students must take personal responsibility for their learning outcomes. He recommended the use of professional networking platforms like LinkedIn, emphasizing their value in facilitating meaningful connections, expanding one’s professional network, discovering job opportunities, and staying updated on industry trends and insights.
Ms. Kemigisha underscored the importance of building supportive peer networks. “Form groups and inspire each other with rewards based on academic excellence,” she advised, emphasizing that academic group work, peer mentorship, and study circles can be powerful tools for motivation and accountability. According to her, surrounding oneself with goal-oriented individuals creates a positive learning environment that fosters growth and resilience, especially when faced with academic challenges.
The orientation programme served as a platform to introduce First Year students to the academic programmes, services, and student life at CoNAS and the University in general. The session led by the Deputy Principal, Prof. Juma Kasozi featured presentations by both College and University leaders, who sensitized the new students on key university policies, academic structures, and support services. School Deans and Heads of Departments in attendance briefed students on the specific programmes offered within their respective units. These included the Dean, School of Physical Sciences, Prof. Michael Owor; the Dean, School of Biosciences, Prof. Arthur Tugume; the Head, Department of Biochemistry and Systems Biology, represented by Dr Joel Isanga; the Head, Department of Chemistry, Dr Emmanuel Tebandeke; the Head, Department of Geology and Petroleum Studies, Dr Arthur Batte; the Head, Department of Mathematics, Dr Ismail Mirumbe; the Head, Department of Physics, Dr Denis Okello; the Head, Department of Zoology, Entomology, and Fisheries Sciences, Dr Godfrey Kawooya Kubiriza; the Head, Department of Plant Sciences, Microbiology, and Biotechnology represented by Dr Godwin Anywar, and a representative from the Department of Exercise and Sports Science. Students were also sensitized on the registration and examination processes, ICT support services, library services, fees payment policies, the Anti-sexual Harassment Policy, counselling and guidance services, the emerging leaders programme, and general welfare at the University.
On behalf of the Principal, the Deputy Principal, Prof. Juma Kasozi warmly welcomed the newly admitted students to the College.He provided an insightful overview of the key academic units and programmes offered both within the College and across the University. In his address, Prof. Kasozi congratulated the students on securing admission into one of the most competitive, vibrant, and intellectually rigorous colleges within the University. He encouraged the students to take full ownership of their academic journey, emphasizing the importance of commitment, discipline, and focus from the very beginning. Highlighting the value of hard work and determination, he reminded them that the foundation they lay now will shape their future success.
In his address, the Manager of the Counselling and Guidance Centre at the University, Mr. Henry Nsubuga, emphasized the importance of safeguarding mental health. He urged students to prioritize their psychological well-being, noting that maintaining a healthy mind is fundamental for academic success and overall personal development. Mr. Nsubuga encouraged students to actively seek support and adopt positive coping mechanisms to navigate the pressures of academic life.
The lectures are expected to commence on Monday, 11th August 2024.
Essential ICT platforms to guide academic work
- Student Portal – https://myportal.mak.ac.ug/
- Email activation – https://sso.mak.ac.ug/
- Webmail – https://webmail.mak.ac.ug/
- Online learning Platform – https://muele.mak.ac.ug/
- Library System – https://mulib.mak.ac.ug
- Knowledge base – https://answers.mak.ac.ug/
- Ticketing system – https://support.mak.ac.ug/
- Mak Policies – https://policies.mak.ac.ug
- DICTs Youtube Channel – @dictsmakerere
- MAK AIR & Eduroam – Use your mak email and its password
Natural Sciences
Makerere Researchers Call for Urgent Conservation of Medicinal Plants in Eastern Uganda
Researchers from the Department of Plant Sciences, Microbiology, and Biotechnology at the College of Natural Sciences (CoNAS), Makerere University have highlighted the urgent need to conserve medicinal plants in the face of increasing threats from climate change, over-harvesting, and habitat destruction.
Despite Namutumba District’s rich diversity of medicinal plants, conservation efforts are limited, and several species are already classified as globally and nationally threatened. This highlights the urgent need for focused conservation strategies to safeguard these vulnerable medicinal plants.
Under a project titled “Knowledge, Attitudes, and Conservation of Commonly Traded Medicinal Plants in a Climate-Changing Environment in Eastern Uganda,” a team of researchers led by Dr Patience Tugume documented 174 medicinal plant species. The goal was to assess the existential threats facing these plants due to unsustainable harvesting practices and the lack of effective conservation measures. These species are widely used to treat various health conditions, including malaria, syphilis, diabetes, hypertension, and certain cancers. The findings of the study are intended to guide the development of species-specific, evidence-based interventions to curb possible extinction and loss of medicinal plant resources. The research revealed troubling trends in the availability of key medicinal plants, including:
- The herbalists mostly collected their medicinal plants from bushlands (92.0%), markets (82.3%) and wetlands (74.7%) and were rarely cultivated. This is of great concern regarding the conservation and future availability of these resources.
- It was noted that 36% of the herbal products were made from roots, which presents a conservation threat since the heavy utilization of roots affects the regeneration of the medicinal plants.
- Common plants used were: Kigelia africana (Naibere), Erythrina abyssinica (Ekiyirikiti) and Geranium sauveolens (Lokowe). Kigelia africana was the most cited species by the herbalists, indicating heavy utilization and a high conservation threat if deliberate measures are not taken to ensure its future availability.
- Almost all respondents (289, 96.3%) acknowledged a considerable decline in the availability of 13 medicinal plants species including Aloe wollastonii (Ekigagi), Commiphora africana (Nkulidho), Myrica kandtiana (Mukikimbo) and Acacia sieberiana (Mufundawuzi).
- Four plant species i.e. Tamarindus indica (Enkoge), Warburgia ugandensis (Balwegira), Mitragyna rubrastipulata (Mutamatama) and Mondia whitei (Mulondo) appear on the Red List of Globally and Nationally Threatened Species and were mentioned among the plants whose population has greatly declined.
- The causes of decline in availability of medicinal plants included climate change, overharvesting, agricultural expansion, habitat destruction, land use change and inadequate regulations.
- There were no medicinal plant conservation efforts by herbalists.
The study recommended the following practices to ensure conservation of the medicinal plants:
- Promote the use of sustainable harvesting techniques to ensure conservation of medicinal plants.
- Conduct capacity building for stakeholders in the medicinal plants sector on conservation, value addition and standardization.
- Establish community botanical gardens raw plant collection and sensitization programmes.
- Advocate for agroforestry among herbalists to reduce the dependence on natural habitats.
- Develop and enforce regulations on accessing natural areas for medicinal plants.
- Promote conservation awareness campaigns.
Research Dissemination in Namutumba District
At the research dissemination workshop held in Namutumba District on 23rd July 2025, and attended by district leaders, researchers, and local herbalists, the project team led by Dr Patience Tugume expressed hope that the insights gained from the project, particularly in medicinal plants conservation approaches, will be invaluable for minimising the decline in medicinal plants.
In her remarks, Dr Tugume, thanked the Government of Uganda through the Makerere University Research and Innovations Fund (MakRIF) for funding the project. She expressed gratitude to the research team composed of Dr Abubakar Sadik Mustafa, Dr Jamilu E. Ssenku, Dr Savina Asiimwe, and Dr Abdul Walusansa who have worked with her closely from project inception in February 2024. She further thanked the research assistants and all respondents, mainly the herbalists that participated in the study.
In a special way, she appreciated Mr. Fred Aggrey Bangu (Resident District Commissioner), Mr. Ofwono Emmanuel (Chief Administrative Officer), Mr. Kiire Noah (Communication Officer), Mr. Mugunywa Enock (District Community Development Officer), Mr. Kirya Moses (District Environmental Officer), Mr. Bamusubire William (District Forest Officer) and the leaders of herbalist associations for providing support throughout the study and sparing time to attend the dissemination workshop.
Addressing the participants, the Resident District Commissioner, Mr. Fred Aggrey Bangu urged all stakeholders to engage in a collaborative discussion on how the study findings can be translated into practical solutions to promote sustainable use and conservation of commonly used medicinal plants in Namutumba District amidst adverse effects of climate change.
Mr. Ofwono Emmanuel, the Chief Administrative Officer, praised the Makerere research team for selecting Namutumba as the study area. He said the research served as an eye-opener to the district officials and community, especially regarding the pressure exerted on natural medicinal resources.
Report compiled by Dr Patience Tugume and Dr Abubakar Sadik Mustafa – Department of Plant Sciences, Microbiology and Biotechnology, CoNAS, Makerere University
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