Fungal endophytes are fungi that reside within plant tissues without causing apparent harm. These symbiotic organisms are ubiquitous, found in nearly all plant species, inhabiting various tissues, including leaves, stems and roots. Endophytes offer numerous benefits to their host plants such as enhanced resistance to pathogens, improved tolerance to environmental stress and increased growth and nutrient acquisition. They achieve these benefits through mechanisms such as the production of bioactive compounds which help control cancer cells and inhibit pests that damage crops, modulation of plant hormone levels and enhancement of the plant’s immune response. The study of fungal endophytes is an important field of research with potential applications in agriculture, biotechnology and medicine.
In this context, a groundbreaking research study titled ‘Phylloremediation of Pyrene and Anthracene by Endophytic Fungi Inhabiting Tea Leaves (Camellia sinensis (L.) Kuntze) in Sri Lanka’ has been conducted by a collaborative team from the University of Kelaniya and the University of Sri Jayewardenepura. This study forms part of the PhD research of Dr. Kasun Thambugala from the Genetics and Molecular Biology Unit at the Faculty of Applied Sciences, University of Sri Jayewardenepura. This article is based on a discussion held with Professor Sagarika Kannangara, a researcher involved in this collaborative research.
Unexplored in Sri Lanka
This research is notable for its focus on fungal endophytes inhabiting tea leaves along with their potential in degrading poly aromatic hydrocarbons (PAHs), an area which is previously unexplored in Sri Lanka. While various research groups in the country have studied and identified fungal endophytes and their capabilities separately, none have specifically investigated those residing in tea leaves and their application as bio-remediators. This study not only advances our understanding of fungal endophytes but also opens new avenues for utilising these organisms in environmental remediation and sustainable agriculture.
Tea plants in Sri Lanka grow in areas with extreme weather conditions and lack cover crops, exposing them to high dehydration and evapotranspiration. The tea leaves also contain substances such as resins and caffeine that obstruct microbial growth. Despite these challenging conditions, the research team identified fungal endophytes that have the potential to live on these tea leaves. Therefore, the research team aimed to identify these fungi and assess their special capabilities.
The study targeted aromatic hydrocarbons present in vehicular emissions, specifically pyrene and anthracene, which are harmful to humans and other species, in order to examine the specific capabilities of these fungal endophytes. These hydrocarbons are released into the air from various human activities, such as vehicular emissions and oil refinery processes and are deposited on various substrates. One of the major substrates on which these hydrocarbons are deposited is plant leaves. The researchers investigated whether the fungal endophytes in tea leaves could degrade these hydrocarbons and identified the kinetic model of their degradation process.
Studies in China and Thailand, which demonstrate the degradation of these hydrocarbons by fungal endophytes, serve as inspiration for this research. This study in Sri Lanka builds on that foundation, demonstrating that fungal endophytes in tea leaves can effectively degrade harmful pollutants. Notably, tea leaves have a thick waxy cuticle that makes it difficult to remove these pollutants even by washing as PAH s are tightly bound to this waxy layer. The researchers discovered that most of the fungi naturally living on/in tea leaves can degrade these hydrocarbons and use them as an organic source.
Hydrocarbon degradation
The team collected tea leaf samples from across Sri Lanka and conducted laboratory experiments to identify fungi with the highest potential for hydrocarbon degradation. They found that the isolated fungi, including Colletotrichum gloeosporioides, Colletotrichumsiamense, Daldiniaeschscholtzii, Phyllostictacapitalensis, and Pseudopestalotiopsis chinensis, showed significant potentials in degrading pyrene and anthracene.
The research team plans to explore the application of these findings further by identifying the genetic and enzymatic mechanisms behind hydrocarbon degradation. One of the remarkable benefits of fungal endophytes is their potential for commercial production and application in bioremediation. These microorganisms particularly can be introduced to environments contaminated with hydrocarbons, where they degrade the pollutants and grow by using them as a source of nutrients. This self-sustaining mechanism eliminates the need for repeated introductions, making the process more efficient and cost-effective.
The study also highlights the potential health risks posed by hydrocarbons in tea leaves, as these pollutants can directly enter the human body through consumption. These hydrocarbons can cause cancer as well as gene mutations in the human body. Apart from that, they can also cause undiscovered disorders for not only human beings but also for other species. By identifying fungi capable of degrading these substances, the research offers a promising solution to mitigate these risks.
The study also explored the mathematical models of hydrocarbon degradation, concluding that the degradation abilities of the isolated endophytes fit best with the first-order kinetic model. This finding adds a theoretical dimension to the practical applications of the research.
Despite the significant findings, the research faced challenges due to limited funding. The current economic conditions in Sri Lanka make it difficult to acquire the chemicals and instruments for such studies. The researchers emphasise the need for financial support.
Healthier planet
This study on fungal endophytes in tea leaves offers numerous opportunities for future research and commercial applications. It can serve as a preliminary study for other researchers and contribute to developing new fungal endophytes for bioremediation. Given the absence of organisms for bioremediation in Sri Lanka, this research could significantly benefit the country’s economy through the export of commercial products derived from these microorganisms. This groundbreaking research underscores the importance of supporting scientific endeavours that address environmental challenges and promote sustainable agricultural practices. With adequate funding and resources, the potential applications of fungal endophytes in environmental remediation could revolutionise the field and contribute to a healthier planet.
Since this research is a collaborative effort, the research team includes Prof. Sagarika Kannangara and Prof. Anupama Daranagama from the Department of Plant and Molecular Biology at the Faculty of Science, University of Kelaniya; Dr. Kasun Thambugala and Dr. Lanka Undugoda from the Department of Biosystems Technology at the Faculty of Technology, University of Sri Jayewardenepura; Dr. Nadeeka Premarathne and Senior Lecturer Jayantha Munasinghe from the Department of Mathematics at the Faculty of Science, University of Kelaniya and Ms. Nadeema Dharmasiri from the University of Sri Jayewardenepura.
