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
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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