Gaps in global wild crop collections

Danielle Haddad and Ruth Harker report on the results of the global gap analysis paper 'Global Conservation Priorities for Crop Wild Relatives', published in Nature Plants on 21 March 2016.

The plants of the Palm house growing around a pathway through the greenery

Global pressure

Intensified livestock farming, land use changes, climate change and increasing population size are expected to have global consequences for food security and agriculture, and are considered as major threats to crop wild relative (CWR) species globally. With an increased demand for food, and limited land resources, the pressure has never been greater to secure the world’s food supply. 

With this in mind, CWRs are the greatest source of untapped crop diversity, and the richest source of diversity for adaptive characteristics needed to confront the challenges of climate change. Whatever the methods used to improve agriculture, plant breeders need genetic diversity and the best place to find this is in the wild.

Missing crops

The new research produced by The International Center for Tropical Agriculture (CIAT) in coordination with the Global Crop Diversity Trust (Crop Trust) and the Royal Botanic Gardens (RBG), Kew has revealed significant gaps in the world’s genebanks. This is both in terms of species and regions with over 70% of essential CWR species in need of urgent collection including banana, plantain and sorghum. This is the first time a global 'atlas' will be available for plant scientists, conservationists and funding agencies to find out which crop wild relatives should be collected, and where.

The study mapped 1,076 CWR of the world’s 81 most important crops for food security and compared predicted CWR distributions with records from the world’s major genebanks. The 81 crops analysed were chosen with respect to their importance in several categories including food security, income generation and sustainable agricultural production. They ranged from cereals (major and minor), oil crops, roots and tubers, vegetables, fruits, forages and spices.

The results provide the most comprehensive list of gaps within collections of CWR species currently in place, and show that 29% (313) of the wild relative plant species analysed, are completely missing from the world’s major genebanks. Furthermore, 23.9% (257) of species are represented by fewer than 10 samples, leaving out a substantial amount of potentially important plant diversity. In total over 95% are insufficiently represented, in terms of geographic range and ecological variation in their native distributions.

The leading author Nora Castañeda-Álvarez and co-author Colin Khoury (both scientists at CIAT) discovered that many wild relatives that are vital for food security desperately need collecting and conserving in genebanks such as the Millennium Seed Bank. These include the wild relatives of bananas and plantain, sorghum and sweet potato. Wild crops such as rice, wheat and potato that have the tendency to be better represented within genebanks were still considered to have significant gaps in their collections.

Where in the world?

The gap analysis identified critical worldwide collecting gaps with occurrences ranging from the Mediterranean and Near East; western and southern Europe; Southeast and East Asia; and South America.

Each area demonstrates various significant threats which increase the challenges of collecting and conserving high priority CWR. Threats can vary from land use changes and deforestation in Southeast Asia, to the threat of war and civil strife in Syria, Afghanistan and Lebanon: such as Aegilops juvenalis (Thell.) Eig distributed throughout Iraq and Syria and Pisum fulvum Sibth. & Sm found throughout Egypt, Greece, Israel, Jordan, Lebanon, Syria and Turkey.

Unlocking the wealth of information

Ruth Harker, Collecting Guide Compiler for the CWR project at Kew shares her aspect of the research:

I was involved in the data gathering part of the gap analysis work, this element involved unlocking the wealth of critical biodiversity information contained within the herbarium collections held in herbaria all over the world.

This phase of the work was a truly global and collaborative effort; and being based in London, I focused on the collections in the UK and Europe, concentrating on collections from RBG, Kew, the Natural History Museum London, Royal Botanic Gardens Edinburgh, and Leiden.

I spent time in each of these herbaria, locating and photographing the specimens (and labels) that we were interested in so that they could be sent to and digitised by a team working at CIAT in Colombia. Some of the challenges that this digitising team faced was the difficulty in databasing from photographs rather than real specimens; and the problems of identifying features such as flowers and fruit without having the original specimen to examine. We aimed to resolve this by using coloured cards to indicate on the photographs whether the specimen was in fruit or flower.

Not only did we source information directly from herbarium specimens, but also from institutional and individual researchers’ databases. This all contributed to the huge dataset that CIAT used in the gap analysis work.

This work is a great example of how Kew’s historical collections can be used directly for cutting edge scientific research and how important it is that information held within herbaria is accessible to researchers.

Filling the gap

The Adapting Agriculture to Climate Change: Collecting, Protecting and Preparing Crop Wild Relatives project is actively working to fill these crucial gaps in CWR collections by using the data to collect and conserve 29 target crops including wheat and rice. The project is a global 10-year initiative, generously funded by the Norwegian government, and managed by the Global Crop Diversity Trust in partnership with the Millennium Seed Bank. The project is being implemented in close collaboration with national and international organisations involved in crop conservation and breeding efforts, including many of the agricultural research centers of the CGIAR.  The CWR team at Kew is actively working in close collaboration with 16 global partners to conserve national CWR in their countries.


Castañeda-Álvarez, N. P., Khoury, C. K., Achicanoy, H. A., Bernau, V., Dempewolf, H., Eastwood*, R. J., Guarino, L., Harker*, R. H., Jarvis, A., Maxted, N., Müller*, J. V., Ramirez-Villegas, J., Sosa, C. C., Struik, P. C., Vincent, H. & Toll, J. (2016). Global conservation priorities for crop wild relatives. Nature Plants doi:10.1038/nplants.2016.22. Available online


Beyond the Gardens: The Crop Wild Relatives Project: This short film explains why the wild relatives of major crops are so important for our future food security and shows how Kew scientists and the Millennium Seed Bank team are helping to safeguard them.

Crop Wild Relatives with Ruth Eastwood of Kew Garden's Millennium Seed Bank: Watch this exclusive interview with Dr. Ruth Eastwood, the Crop Wild Relative Project Co-ordinator at the Millennium Seed Bank of the Royal Botanic Gardens, Kew.