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
Makerere University Convocation has honored Mubiru Enock Joel with an award in recognition of his outstanding academic performance. Mubiru, who graduated with a Bachelor of Science in Mathematics and Physics, scored a CGPA of 4.91, making him the best student in the sciences at Makerere University this year. The award, which included a plaque and a cheque of UGX1 million, was presented to him by the Chair of the Convocation on January 14, 2025, the second day of the 75th graduation ceremony.
Overall, the College of Natural Sciences (CoNAS) presented 310 students for the award of degrees of Makerere University at the 75th graduation ceremony. Of these, 14 graduated with PhD (5 female 9 male), 36 MSc (10 female and 26 male) and 260 BSc (113 female and 147 male).
In the course of the 75th graduation ceremony that started on 13th January and will end on 17th January 2025, a total of 13,662 graduands will receive degrees and diplomas of Makerere University.
Of these, 143 will graduate with PhDs, 1,813 with Masters degrees, 11,454 with Bachelor’s degrees and 243 with postgraduate diplomas. 53 % of the graduands are female and 47% are male. 44% of the PhD graduands are female. A total of 491 graduands will receive first class degrees. 16% of the students will be graduating with post-graduate degrees and diplomas.
Chancellor’s Address
In his address, Makerere University Chancellor Dr. Chrispus Kiyonga congratulated the graduands on their success and expressed appreciation for the support provided by the lecturers, administrators, parents, and guardians. He emphasized that the success of the university is a collective effort, appreciating the faculty and University Council for their critical roles in delivering quality education.
Dr. Kiyonga also extended his gratitude to the President of Uganda, H.E. Yoweri Kaguta Tibuhaburwa Museveni, and the NRM government for their invaluable financial support to Makerere University. The Government has so far allocated UGX30 billion to Makerere University through the Research and Innovations Fund (Mak-RIF).
Looking to the future, Dr. Kiyonga encouraged the University to increase its outreach programmes, particularly in the agricultural sector. He proposed collaborations with medium- to large-scale farmers, where students could gain hands-on experience while also assisting farmers in local communities. He also advocated for stronger partnerships with the private sector to support the commercialization of innovations emerging from Makerere University.
Furthermore, the Chancellor highlighted the President’s directive to teach Political Economy to all university students. He stressed the importance of transforming Africa through the strategic utilization of its resources and emphasized the value of political economy knowledge in this process.
Vice Chancellor’s Address
In his remarks, Makerere University Vice Chancellor, Prof. Barnabas Nawangwe congratulated the graduands and expressed deep appreciation for the unwavering commitment of the teaching staff, administrators, parents, and guardians. He also welcomed the Chancellor, Dr. Chrispus Kiyonga, emphasizing that his vast experience would be an asset to the institution.
Prof. Nawangwe acknowledged the College of Natural Sciences for providing foundational training for all the other science-based disciplines at the University. He also commended the College for its ground-breaking research and contribution to the development of mathematics in the region. “The College of Natural Sciences is unique because it handles all the foundation disciplines for all the other science-based disciplines. But apart from the basic sciences, the College provides training and conducts research in critical applied science disciplines, including geology and petroleum studies, industrial chemistry, and others. The College is central in the development of mathematics in the East and Central Africa region and it has also taken the initiative to investigate the problem of poor performance in biology by secondary school students,” the Vice Chancellor noted.
He encouraged the graduands to seize every opportunity and to consider starting their own enterprises, using the knowledge and skills they have acquired during their studies. “Do not despair if you cannot find employment. Instead, reflect on the immense opportunities around you and consider entrepreneurship as a path to success,” he urged.
Message from the Minister of Education and Sports
On behalf of the First Lady and Minister of Education and Sports, Hon. Janet Kataaha Museveni, the Minister of State for Primary Education, Hon. Dr. Joyce Moriku Kaducu, congratulated the graduates and thanked the university for its commitment to excellence in education and research. She emphasized the transformative power of higher education and praised Makerere University for its contribution to the nation’s development.
She also expressed gratitude to the parents and guardians, acknowledging their critical role in the success of the students. “Your support has played an integral part in making this achievement possible,” she said.
Commencement lecture by Prof. Puleng LenkaBula
In her commencement lecture, Prof. Puleng LenkaBula, Vice Chancellor of the University of South Africa, expressed gratitude for the support that Makerere University and Uganda provided in the fight against apartheid. She encouraged the graduands to use the knowledge acquired to address the continent’s challenges, particularly in the transformation of Africa and the empowerment of women. Prof. LenkaBula called for greater collaboration among African intellectuals to create a better future for the continent, particularly through research that directly benefits communities.
Research Excellence and Teacher Recognition
At the ceremony, Makerere University recognized outstanding researchers and educators from CoNAS. The Senior Researcher Award was presented to Assoc. Prof. Juma Kasozi (Department of Mathematics), Assoc. Prof. Charles Masembe (Department of Zoology, Entomology and Fisheries Sciences), and Dr. Jamilu Ssenku (Department of Plant Sciences, Microbiology and Biotechnology). The Mid-Career Researcher Award went to Dr. Julius Mulindwa (Department of Biochemistry), Dr. Patience Tugume (Department of Plant Sciences, Microbiology and Biotechnology), and Dr. Patrick Ssebugere (Department of Chemistry), while Dr. Omara Timothy (Department of Chemistry), Dr. Mukiibi Ssewannyaga Ivan (Department of Geology and Petroleum Studies), and Dr. Sadik Mustafa Abubakar (Department of Plant Sciences, Microbiology and Biotechnology) were recognized as the best Early Career Researchers. In addition, Prof. Ann Akol (Department of Zoology, Entomology and Fisheries Sciences), Dr. Sadik Mustafa Abubakar, and Dr. Kalega Peggy (Department of Geology and Petroleum Studies) were honoured as the best teachers of the year from CoNAS.
Transcripts and Certificates
Graduates who participated in today’s ceremony can collect their transcripts from their respective colleges.
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