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Boosting Tea Plant Diversity, Quality and Resilience in Sri Lanka

SRL5050 - Boosting Tea Plant Diversity, Quality and Resilience in Sri Lanka

Tea was first introduced to Sri Lanka by the British in the 1820s and commercialized in 1867. Today, the tea industry is the country’s leading foreign exchange earner and employs directly or indirectly two million Sri Lankans. (Photo: Tea Research Institute of Sri Lanka)

Above all things, Sri Lanka is known for its tea. Introduced in the nineteenth century, Ceylon tea today is a multi-billion-dollar industry that brings in wealth and tourism. The country has plans to expand tea production and improve its quality but faces serious challenges from climate change and increasing global market competition. Scientists in Sri Lanka, through the IAEA’s technical cooperation programme, are now looking to a nuclear technique to overcome these obstacles by enhancing tea plant productivity through increased genetic diversity.

Leading this effort is Mahasen AB Ranatunga, the Head and Principle Research Officer at the Tea Research Institute of Sri Lanka’s Plant Breeding Division. His Institute is continuously looking for ways to develop and cultivate new breeds of tea. “Because tea is not native to Sri Lanka there isn’t much genetic diversity, and despite our enormous tea output, we only have seven different types of regional tea. Working with the IAEA and the Food and Agriculture Organization of the United Nations (FAO), we’re hoping to use new nuclear techniques, alongside conventional ones, to increase our island’s tea diversity,” Ranatunga said. Improving genetic diversity is important because genetically diverse crops are more resistant to diseases and can be more adaptive to changing weather patterns.

Inducing diversity

The nuclear technique Ranatunga is banking on is single-cell induced mutagenesis, an irradiation method involving a radioactive source and single plant cells. Using irradiation to develop new plant varieties is not new and has been used successfully around the world since the 1950s. What is new is adapting it for crops that live longer than two years — perennial plants.

“In Asia and the Pacific, irradiation is often used on seed crops, but there has been a bottleneck on its use in crops that are not propagated from seeds,” said Shoba Sivasankar, Head of the Plant Breeding and Genetics Section at the Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture. Cultivating new plants from clippings is more complex than using seeds and requires specialized knowledge and equipment. Sivasankar’s team is developing procedures to help experts from all over the world induce genetic diversity in perennial and tree crops using single-cell mutagenesis and regeneration, with important work recently conducted on coffee.

The technique uses individual cells from a tea plant that are not typically used in reproduction, like leaf clippings. These cells are isolated in a suspended liquid medium and irradiated. The radiation spurs genetic mutations, and when these single cells are then “cultured” — grown and propagated — into collective tissue, they are genetically uniform. “Developing genetic diversity this way is less complicated and much faster than more conventional tissue culture techniques,” said Sivasankar.

Researchers at the Tea Research Institute of Sri Lanka are developing new lines of tea to improve quality and resilience to disease and climate change. (Photo: Tea Research Institute of Sri Lanka)

Facing climate change

The time frames offered by the nuclear technique – a new strain can be developed in just ten years – is important, as Sri Lanka’s tea industry faces pressures that could affect its position as a leading producer of one of the world’s most widely consumed drink (second only to water).

“Traditionally one of the biggest threats we’ve faced is a disease called blister blight, but that typically only impacts some areas and primarily during wet seasons. We’re concerned about the effect climate change will have on this, making blister blight more frequent and widespread, potentially impacting the quality of our tea,” said Ranatunga.

 “Some of the tea varieties we’re hoping to develop will be able to deal with this change, particularly moisture variation, high temperatures and drought,” he added. The Tea Research Institute’s priority in using induced mutagenesis will be to increase tea yield, quality and resilience to mitigate the severity of these impacts.

This is the first time that the Joint FAO/IAEA Centre supports a project on tea crop improvement using induced mutagenesis. Its impact and lessons could help guide other countries considering enhancing their tea production using the technique.

For Sri Lanka, the severity of climate change on tea can critically impact its economy. Tea is the leading foreign exchange earner in the country, and two million Sri Lankans, roughly 10 per cent of the country’s population, are directly or indirectly employed in the tea industry. Furthermore, up to 70 per cent of Sri Lanka’s tea production comes from small holders, who are likely less able to weather the effects that climate change brings. Ranatunga says they have identified some tea cultivating areas of the island that may be vulnerable to climate change and they expect them to be severely affected.

Action is underway, and the IAEA’s collaboration, through its technical cooperation programme, with the Tea Research Institute primarily involves helping to train staff to use and establish the facilities for single-cell mutagenesis. Mykola Kurylchyk, the IAEA’s Programme Management Officer for Sri Lanka said that even though the COVID-19 pandemic has delayed some of this training, the Agency’s support has helped establish the laboratories needed to undertake this four-year project.

“This is a good opportunity for us and the first time that Sri Lanka has used a technique like this on a plantation crop. We believe this will have a far-reaching impact on a critical industry,” said Ranatunga.

Read more about the IAEA’s technical cooperation programme.

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