As Tony Lass* explains, only a small fraction of the genetic diversity of cocoa is used in the crops grown around the world today. Preserving genetic diversity is essential in the fight against pests and diseases and climate change
Crop diversity is essential to life and underpins nearly everything that we eat and drink, including cocoa and chocolate. However, diversity is rapidly disappearing.
Back in 2007, in an address to the AGM of the Tropical Agriculture Association, Professor Geoff Hawtin noted that that genetic diversity in a crop provides the ability for plant breeders to produce new varieties by combining different traits in new combinations, using a variety of promising individuals.
Today, the value of this diversity is steadily increasing as our knowledge advances. Nowadays, it is possible to identify potentially useful genes – for disease resistance, flavour or growth habit – and use them.
Potential options being lost
However, as Professor Hawtin also noted, with every individual that is lost, we lose options for the future.
Much – but not all – of the natural diversity of the cocoa species originates in forests of the head waters of the Amazon River – in Brazil, Colombia, Ecuador and Peru – an area shown to be a ‘centre of diversity’ for cocoa.
Potentially valuable wild cocoa types are being lost for ever due to intense development pressures from roads, agriculture, mining, tourism, hydroelectric schemes and other developments.
However, plant collectors have potentially saved a meaningful number of these wild cocoa individuals during expeditions to these areas over the last 80 years. Many have now been successfully established in national and international collections and are of potentially huge (but often unknown) future value to cocoa breeders.
This is a very positive development, but much remains to be done. A range of diverse wild cocoa types are essential to achieve success in future breeding programmes that lead to improvements in the sustainability of cocoa production.
Many germplasm collections – including those of cocoa – are themselves under threat from lack of reliable funding. A decade ago this realisation led to the creation (by The Crop Trust & others) of the so-called Svalbard Global Seed Vault in the permafrost of the Arctic Circle in Norway (at – 18 ℃). This facility now holds almost 900,000 seeds permanently held at low temperatures so that they do not germinate.
Living collections essential
Sadly, at present, cocoa cannot be stored in this way and can only effectively be conserved in living collections (as a live plant in a field). Funding for care and maintenance (and then evaluation) of collected wild cocoa individuals needs to be secured to ensure that this material is available for future generations of cocoa breeders.
As of now, long-term funding is not assured at an adequate level and so some of these precious individuals – and thus potentially important cocoa diversity – is being lost for ever. Action is urgently needed to prevent further losses.
Zhang and Motilal (2016) express concern that cocoa production in Africa and Asia is based on some 12-15 cocoa types, mainly Upper Amazon Forastero clones – many of which derive from collections made by Pound in 1938. Breeding efforts in the past 70-80 years have been reshuffling this small fraction of the genetic diversity of cocoa, with little addition of new variations.
The risk of this process is that on-farm genetic diversity in Africa and Asia may not meet the challenge of the mounting pressures of pest and diseases and climate change. ■ C&CI Read more
This article first appeared in the May’18 issue of C&CI, click on subscribe now if you wish to read the full story and other informative articles in the May and future issues of C&CI or log in here if you are already a subscriber.
*Tony Lass is Director of Fox Consultancy Services Ltd and a former Director of Global Cocoa Supplies at Cadbury plc.
Hawtin, G. (2007) Securing crop diversity – assuring the future. Tropical Agriculture Association, AGM November 2007 Lachenaud, P. and Motomayor, J.C (2017) The Criollo Cacao tree: a review. Genet Resour Crop Evol 64: 1807-1820
Padi, F.K., Ofori, A, and Akpertey, A (2016) Genetic base-broadening of cacao for precocity and cropping efficiency. Plant Genetic Resources; 1-10. NIAB, Cambridge
Pound, F.J. (1938) Cacao and witchbroom disease of South America with notes on other species of Theobroma. Yuille’s Printerie Port of Spain, Trinidad. Reprinted in Archives of Cocoa Research 1: 20-72
Zhang, D. and Motilal, L (2016) in Cacao Diseases. Bailey, B.A and Meinhardt, L.H (eds.) pp 3-31, Springer International Publishing, Switzerland