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
Overview
The Ugandan government has increasingly recognized the critical role of science education in driving the nation’s economic development. As such, it has put in place deliberate policies aimed at popularizing science education in schools. This initiative seeks to equip the youth with the knowledge and skills necessary to contribute effectively to the country’s development. Since 2004, science education has been made compulsory in lower secondary schools, and the Uganda Government has continuously emphasized the importance of science and technology through policies like the National Science, Technology, and Innovation (STI) Policy, introduced in 2009. These policies aim to create a strong foundation for the country’s “Transformation for Prosperity,” focusing on technological innovation and development. The introduction of astronomy and space science as part of the curriculum supports this vision, offering students the tools to explore scientific concepts that will drive future innovation.
About the Project – Use of Astronomy and Space Science to Promote Science Education in Schools
In an initiative geared towards bolstering science education in Uganda, Makerere University Department of Physics is leveraging the wonders of astronomy and space science to ignite curiosity and enthusiasm among learners. The project, led by Prof. Florence Mutonyi D’ujanga from the Department of Physics has reached 10 schools in Kampala, Luwero, and Mukono districts, using the vast universe to inspire the next generation of scientists, engineers, and mathematicians. The astronomy outreach activities have impacted numerous schools across different regions in Uganda. The initiative started during the COVID-19 lockdown, with initial outreach to nearby schools in Kampala. As the programme gained momentum, it expanded to various districts, benefiting students from both primary and secondary levels. The schools that have participated in the programme include, Kampala: Makerere College School and Makerere CoU Primary School, Luwero: Mulusa Academy (Wobulenzi), Wobulenzi Bright Parents, Janan Luwum S.S., and Janan Luwum Nursery & P/S, MUkono: Our Lady of Africa S.S., Kyesereka CoU P/S, Mpoma Royal College, and Mpoma Junior School.
Aims and Objectives of the Project
Funded by the Government of Uganda through the Makerere University Research and Innovations Fund (MakRIF), the central aim of this initiative was to use astronomy and space science to capture the imagination of students, encouraging them to embrace the study of science and mathematics. “By engaging students in hands-on, interactive learning activities, the project seeks to improve their performance in these critical subjects. The initiative focuses on making science enjoyable, accessible, and inspiring, fostering a positive attitude toward the subject from an early age,” explained Prof. D’ujanga.
Activities conducted
The project began with a questionnaire to assess the students’ initial understanding of astronomy, followed by tailored outreach activities that addressed gaps in knowledge and sparked excitement about the subject. The activities included;
- Telescope Assembly: Students learned to assemble telescopes using local materials, helping them gain a hands-on understanding of how astronomy tools function.
- Sky Viewing: Students had the opportunity to observe celestial bodies like stars, planets, and constellations, experiencing the universe up close.
- Cultural Astronomy Storytelling: This component introduced students to the rich cultural narratives surrounding astronomy, linking science with history and tradition.
- Astronomy Quiz Sessions: Fun, educational quizzes challenged students’ knowledge of astronomy, stimulating a deeper interest in the subject.
- Planetarium Shows: The project also featured immersive planetarium shows, which are a highlight for many students. These shows provided an exciting visual experience, where learners could see projections of stars, planets, and other celestial phenomena. The planetarium is at the heart of this outreach programme. Traditionally used for educational purposes in the field of astronomy, the planetarium has a hemispheric domed ceiling, which serves as a projection screen for images of celestial objects. The immersive environment fosters curiosity and excitement among learners, laying a solid foundation for further study in science. One of the main objectives of the planetarium shows is to break down the myth that sciences are difficult. By using visual and interactive methods, the project demonstrates that learning about space and the universe can be both fun and inspiring.
Project research dissemination event
On 21st March 2025, the project team hosted a dissemination event at Makerere University to present and share their research findings. The event was presided over by Prof. Winston Tumps Ireeta, the Principal of the College of Natural Sciences (CoNAS) and Acting Deputy Vice Chancellor in charge of Finance and Administration at Makerere University. The event was attended by students, school administrators, as well as representatives from MakRIF and the Ministry of Science, Technology, and Innovation. In her address, the Project Principal Investigator (PI), Prof. Florence D’ujanga, emphasized the importance of sparking curiosity in students to encourage them to pursue scientific studies. “By making astronomy and space science more accessible and engaging, this project seeks to inspire greater interest in science education, ultimately benefiting Uganda’s long-term development in critical fields such as technology, engineering, and mathematics,” she explained.
On behalf of MakRIF, Dr. Mercy Rebekah Amiyo expressed appreciation to the research team for their invaluable initiative in promoting the study of science through astronomy. Dr. Amiyo praised the team’s dedication to making complex scientific concepts more engaging. She called upon the project team to secure property rights and take proactive steps toward the commercialization of the project.
In his remarks, the Guest of Honour, Prof. Winston Tumps Ireeta emphasized the importance of nurturing scientists who understand principles rather than simply memorizing frameworks. He emphasized the importance of early exposure for children to develop an appreciation for science. He expressed gratitude to the Government of Uganda for its continued support towards research activities at Makerere University.
Testimonies by students
Sharing their testimonies about the project, Jonathan Mugabi and James Tanzinge, both S.4 students at Makerere College School, expressed heartfelt gratitude for the opportunity it provided. They noted that the project had ignited a newfound passion for research, significantly expanding their interest in exploring scientific topics. Through their participation, they were introduced to essential scientific vocabulary, which has helped to deepen their understanding of complex concepts. Additionally, the project exposed them to cutting-edge technology, fostering a sense of excitement and curiosity about the role of innovation in science. As a result, both students have developed a strong desire to continue their studies in the sciences at a higher level, inspired by the hands-on experiences and knowledge they gained from this initiative.
Click on the link below for the pictorial of the dissemination conference;
https://drive.google.com/drive/folders/1Wv5xLOwiNe8Tc9uOWBpt9xvOtwffLHdo?usp=sharing
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