Wild Arabica species: The genetic key to a sustainable coffee industry

A.S. Thomas’s 1942 entry into the Empire Journal of Experimental Agriculture is a reminder of times gone by. In an account of his exploration of the Boma Plateau, Sudan, to search for wild Arabica (Coffea arabica), Thomas refers to neighbouring “Abyssinia”, the historical name that included Ethiopia, as well as the then colonial “Anglo-Egyptian Sudan”. Sadly, dated political references are not the only sign of the article’s age. Written at a time before climate change had taken its toll on the planet, Thomas wrote of Arabica trees 5.5 metres  high and trunks over 17 centimetres in circumference. A recent visit to the region by a World Coffee Research (WCR) delegation, the first since Thomas’s 1941 visit, found that the healthy wild Arabica plants the researcher had encountered were also now a thing of the past. “It’s a bleak situation at the centre of origin,” says Timothy Schilling, Executive Director for WCR, who led the South Sudan expedition in April this year. The goal of the expedition was to follow in Thomas’s footsteps, locate the wild Arabica and later collect germplasm – a collection of genetic resources for an organism – for further research and plant development. South Sudan, and neighbouring Ethiopia, is the epicentre of wild Arabica, Schilling explains, and the collection of this wild species from the former locality is extremely rare. This most recent trip was hosted by staff members from the USAID-funded project JGMUST: A Consortium for Development, based at the John Garang Memorial University for Science and Technology in Bor, South Sudan, led by the Norman Borlaug Institute for International Agriculture of the Texas A&M University System. Doctor Aaron Davis, from the Royal Botanic Gardens, Kew, United Kingdom, joined Schilling on the trip, for what was not his first expedition to find a wild coffee species. Since 1997, Davis has travelled the world and discovered more than 20 wild coffee species, encountering everything from winged coffee that floats on water to the world’s largest coffee beans. The purpose of these expeditions has been about exploring the diverse gene pool that exists for coffee in the wild. Davis explains that as his research progresses, he’s finding increasing links with the commercial coffee industry. He says it’s been alarming to discover that the coffee industry – which represents the livelihoods of around 100 million people around the world – is dependent on limited fundamental scientific information. “We know that the industry relies on a narrow gene pool,” says Davis. “Compare that to the situation in the wild – where there are huge amounts of genetic variation, associated with a vast spectrum of different traits. There is certainly huge potential here for the long-term sustainability of the industry.” Davis says that research into wild Arabica in Ethiopia has already helped combat certain diseases of coffee. Moving forward, however, the limits to how much the industry can benefit from wild Arabica will be defined by the extent of existing germplasm collections. “You can store a certain amount of genetic information in a collection, however you can’t think you have everything,” he says. Davis notes that even from one year to the next, sampling can be done in the same general area and each expedition will turn up different information. “Of 1000 plants, say you collect 100, there is a good chance that you haven’t captured the genetic variation you require, unless you evaluate the genetic diversity of the population beforehand,” he says. Wild plants remaining in situ (their natural habitat) are still dynamic and evolving, Davis explains. Once they are taken out of this environment, the potential for adaptation is reduced. As such, Davis points to the importance not only of collecting samples to be kept ex situ, that is in artificial environments in frozen germplasm or living plant collections, but of also protecting these plant populations in situ – in places where they naturally occur. The recent South Sudan expedition, however, indicated that climate change, in conjunction with other compounding factors (i.e. land-use change) is now seriously threatening the future of wild Arabica in situ. “It was a big shock for us to see the state of the South Sudan wild Arabica populations compared to that reported by Thomas in 1942,” says Davis. The Boma plateau is lower than many of the Ethiopian Arabica forests, with the highest peak in the South Sudan Arabica region not exceeding 1600 metres. In Ethiopia, which has many highland forests above 2000 metres, Davis explains that climate change is likely to see the forests move up the mountainside to cooler region areas. “But in South Sudan, it has nowhere to go,” he says. Davis and his team have been undertaking research in climate change modelling, not only taking into consideration a changing temperature, but also technology that looks at all the environmental factors influencing production and survival. The full results of this research are soon to be released, and Davis believes his conclusions will be a cause for alarm among the coffee industry as a whole. This latest South Sudan expedition, in the descriptors used by Thomas versus what he and the WCR team have seen, provides a strong indication that the modelling has validity. “In 20 years, wild Arabica populations in South Sudan might not be there at all. And those traits that could be useful for the coffee industry to maintain the sustainability of Arabica production, could be lost forever,” says Davis. “Wild Arabica occurs in Ethiopia and South Sudan, and that’s it.” The result of these findings means that the trip to South Sudan could be seen a “rescue mission” for those wild Arabica populations as much as anything else. Davis says that damage from deforestation also constitutes a serious threat to wild Arabica. “In some places, climate change won’t even have a chance to influence the fate of Arabica – there will be no forest, and no forest means no Arabica,” says Davis, pointing to the knock-on effects of civil war and the encroachment of fire into evergreen forests, diminishing the health and viability of natural Arabica populations. WCR will be setting up three subprograms for the collecting, screening and cataloguing of the Arabica germplasm base, to help sustain coffee biodiversity and genetic variability, according to WCR’s Statement Regarding Coffee Biodiversity. The organisation plans on working with the Ethiopian and South Sudanese governments to collaboratively collect wild germplasm, with the genetic material remaining the biological property of the respective country. WCR plans on preserving a targeted selection of genetic diversity by creating a “frozen gene bank” by cryopreservation of seed or somatic embryos. Another of WCR’s objectives is to screen and catalogue current Arabica varieties and establish agreements in collaboration with their germplasm curators. Moving forward, they will create and coordinate a worldwide database for Arabica germplasm, in an attempt to unite diffuse core collections in order to develop pre-breeding populations in selected target countries. “We’re putting a greater emphasis at WCR to tackle the germplasm issue head on and be a coordinating and facilitating unit,” says Schilling. “We’re proposing a comprehensive plan to put existing germplasm collections in deep freeze.” This most recent trip has added a new sense of urgency to this part of the WCR mandate, with the fear that the wild genetic material found in South Sudan may soon disappear. This initial expedition was mainly to locate the plants, and WCR will work with the South Sudanese government to return to the region in November/December to collect samples once the trees have fruits. The Borlang Institute will then manage the collection with the Sudanese university. “This is really important, we could be losing huge treasures,” says Schilling. “We need to revitalise and preserve the available populations before climate change and other factors degrade these forests any further.” 

Leave a Reply

Send this to a friend