Natural Sciences
Mak Scientists Unveil New Method of Measuring Stress Levels in Plants
Just like animals and human beings, plants too can be stressed. Whereas one may easily detect stress in animals and humans basing on their behavior, plant “behavior” is not easy to interpret.
Why should we be concerned about stress in plants?
Plants under stress cannot reproduce or grow well because they have to divert much of their physiological energy to fighting stress. If the plants are critical food crops, this will lead to perpetual food shortages because their energy resources are spent fighting stress.
New study on measuring stress in plants
A new study titled “Sandwich Enzyme-Linked Immunosorbent Assay for Quantification of Callose” 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 stress in plants can be measured. According to Prof. Arthur Tugume, the lead scientist of this study and expert in plant diseases, when plants are stressed, they produce numerous molecules within their cells mostly as means of adapting to stress or avoiding the impact of stress. “For example, plants produce reactive oxygen species like hydrogen peroxide, superoxide ions, and hydroxyl ions. These reactive oxygen species are produced rapidly and act as rapid messengers in the plant tissues to activate additional responses spreading over the entire plant body. This helps the plant to withstand or avoid the impact of stress”.
Dr. Ssenku E. Jamilu, a plant physiology expert on the team explains that in plants, stress can be induced by many factors such as pollution in the soil and atmosphere, high soil salinity (salt stress), excessive lack of water (drought), extreme temperatures, lack of oxygen (anoxia), excess radiation, mechanical injury by wounding or by pests that feed on the plants, and infestation by disease-causing microorganisms (pathogens). “Such factors are worsened by climate change, implying the importance of measuring their impact on individual plants to guide plant breeding programmes to ensure sustainable food production in the face of climate change”.
The research indicates that reactive oxygen species set in motion additional processes to ensure limited impact of stress on the plant. For example, a unique carbohydrate, named “callose” starts to accumulate in large quantities within plant cells as a means of fortifying plant cells. Callose differs from the other usual plant carbohydrates such as starch or cellulose because of the way its structures are formed. Also, the production of callose gets increased during stress. Callose acts as a road-block to any pathogen such as bacteria by limiting bacterial movement that would otherwise ease attack on other tissues or cells.
“If we can artificially induce the stress on the plant, and then measure the amount of reactive oxygen species or callose or any other responses in the plant, we should be able to directly and quantitatively measure the stress,” Prof. Tugume explains.
He however notes that callose participates in many other normal developmental processes of plants and for that reason, there is always some “housekeeping” callose in the plant tissues even without stress. “This means that one must be able to accurately and quantitatively distinguish between ‘stress-induced’ and normal ‘housekeeping’ callose”.
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. This bacterium induces so much stress on the banana plants resulting into a destructive disease known as banana xanthomonas wilt (BXW), the most destructive disease of bananas in East and Central Africa.
The banana leaves, pseudostems and corms were analyzed for callose and compared with the control plants that had been inoculated with water instead of bacteria. The analysis was done using a method called S-ELISA (Sandwich Enzyme-linked immunosorbent Assay), that was designed by scientists in this study. This method is specific to callose.
Callose-specific primary antibodies were used to coat the wells of 96-well microplates followed by incubation with callose extracts from tissues of stressed plants. Additional incubation with same primary callose-specific antibodies was done, and finally, incubation with a secondary antibody that is conjugated to an enzyme. When a substrate is supplied to the enzyme, colour changes were monitored. The presence of callose (and thus stress on the plants) was assessed quantitatively by measuring the intensity of color change resulting from enzymatic action on the substrate. This method proved effective in comparison to the gold standard method of detecting and quantifying aniline blue stained callose using fluorescence microscopy.
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, his method is new and can be applied to any plant that is subjected to any stress because generally, plants produce callose in response to stress.” Mr. Mustafa further states that the method is convenient because, if necessary, samples can be processed between a few hours to one year (or even longer), which allows exchange of materials between laboratories and countries when needed, something that was not possible before. The S-ELISA method used 96-well plates which allows high throughout studies, hence, hundreds of samples can be analyzed simultaneously within a few days.
This study has been published as a Protocol by Multidisciplinary Publishing Institute (MDPI) in an open access journal, “Methods and Protocols”, in the section: Biochemical and Chemical Analysis & Synthesis and is freely accessible on https://www.mdpi.com/2409-9279/5/4/54/htm.
The research 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, the Alliance for Bioversity International and International Centre for Tropical Agriculture (CIAT) and CABI.
For more details, contact;
- Prof. Arthur Tugume, Lead Scientist of the study, College of Natural Sciences, 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, 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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