Crop diversity, wild relatives, and food security- PhD completed!
This past week, DAPA’s visiting researcher Colin Khoury successfully completed his PhD at Wageningen University in the Netherlands, defending his thesis titled “The conservation and use of crop genetic resources for food security”.
Crop genetic diversity is a critical resource to address the nutrition and agronomic challenges facing global food security. Increases in use of this diversity are expected but are dependent upon conservation, availability, and access. Considerable erosion of crop genetic diversity has occurred in situ, i.e., in farmers’ fields and natural habitats, and the variation conserved in ex situ genebanks is also vulnerable due to insufficient resources. The window of opportunity to resolve these deficiencies and thus accomplish a comprehensive global system for crop genetic diversity conservation and availability for use will not remain open indefinitely.
Among the factors hindering the conservation of crop genetic resources is a lack of essential information regarding this diversity. Questions include: (a) what is the status of diversity in our food systems, and where are the greatest vulnerabilities?, (b) where can genetic diversity be found that can be useful in increasing productivity and mitigating these vulnerabilities?, (c) is this genetic diversity available in the present and in the long term?, and (d) what steps are needed to improve the ability for researchers to access genetic resources critical for present and future crop improvement?
Colin’s PhD aimed to contribute to the knowledge required to answer these questions through an exploration of the need for, potential of, challenges and constraints regarding, and necessary steps to enhance the conservation and use of crop genetic diversity. The research started with an investigation of the state of diversity in global food supplies, finding that national food supplies around the world have become increasingly similar over the past 50 years, gaining in calories, protein, and fat, as animal-derived foods and high-calorie plant foods have risen in importance. The proportion of diets consisting of major cereals, sugar crops and oil crops has increased, while regionally and locally important cereals, root crops, and oil crops have generally become further marginalized.
The thesis then delved into the potential for utilization of a particular set of genetic resources of increasing interest globally – crop wild relatives. These wild cousins of cultivated species have been used for many decades for crop improvement. Their utilization is likely only to increase due to improvements in information on species and their diversity, advancements in breeding tools, and the growing need for exotic genetic diversity in order to address compounding agronomic challenges. As wild plants they are subject to a myriad of human caused threats to natural ecosystems. A focus on wild genetic resources is thus timely both for biodiversity conservation and food security objectives.
Research on crop wild relatives first concentrated on the identification of potentially important wild genetic resources at the national level in the United States. The resulting National Inventory listed close to 5000 taxa. A prioritization of species based on value to food security emphasized 300 native taxa that are most closely related to important food crops.
Once potentially valuable genetic resources are identified, subsequent information is needed regarding where they occur, what diversity they may possess, and how well conserved and therefore available to crop breeders they are. A ‘gap analysis’ methodology was proposed to answer these questions, capitalizing on developments in digital occurrence and eco-geographic data as well as species distribution modeling, intentionally utilizing freely available software and data, and incorporating a novel expert evaluation tool.
The thesis then advanced the now five year-old gap analysis methodology, taking advantage of improvements in species targeting, occurrence data, modeling, and expert feedback methods, and further utilizing eco-geographic information to identify traits of value to crop improvement objectives. In case studies on the wild relatives of sweetpotato [Ipomoea batatas (L.) Lam., I. series Batatas], and pigeonpea [Cajanus cajan (L.) Millsp.], related species were found to be highly under-represented in ex situ conservation systems and thus inadequately available to breeders and researchers. Species differed among themselves and in comparison to the associated crop in their adaptations to temperature, precipitation, and edaphic characteristics, and many species also showed considerable intraspecific variation. Taxa and specific geographic locations were prioritized for further collecting in order to improve the completeness of germplasm collections for these important crops.
While conservation of crop genetic diversity is fundamental to the availability of this diversity for breeding, national and international policies determine the capacity for researchers to acquire these resources. The thesis culminated in an exploration of the degree to which international collaboration is potentially required in order to achieve access to genetic resources where they are needed. Countries were found to be highly dependent on crops whose genetic diversity largely sources from outside their borders. This reliance is evident even in countries located in regions of high indigenous crop diversity and has increased significantly over the past half century, bolstering evidence for the need for effective national and international policies to promote genetic resource conservation and exchange.
Colin’s PhD involved collaborations with a diverse list of researchers within DAPA and in genebanks, herbaria, universities and other organizations around the world. The results presented in this thesis have been received by the scientific community and the public with remarkable interest. The research on homogeneity in global food supplies was covered extensively by the media, with over 300 articles, blogs, and podcasts published in the first year following its release, including in newspapers and journals such as Scientific American, Time Magazine, and National Geographic. The article also received CIAT’s 2014 Outstanding Research Publication Award.
Research on crop wild relatives has also received considerable attention. The highly cited gap analysis methodology has become a central method paper in the field of exploration of diversity of wild relatives, and subsequent articles have a high number of viewings by scientists and the public. The National Inventory of the United States was also covered in American media and received the 2014 Crop Science Society of America C8 Division “Outstanding Papers in Plant Genetic Resources” award.
A number of lines of research presented in the PhD are ongoing. Numerous crop genepool based gap analyses, bringing together a variety of associated researcher experts, are in planning or have been initiated. A cumulative global analysis communicating conservation concerns for over 1000 wild species related to 80 crops is also being published. Building upon the National Inventory of the United States, agencies are collaborating on refining knowledge on conservation concerns, performing targeted collecting, and establishing management plans for the conservation of key iconic wild relatives in situ. Finally, the research on interdependence among countries on crop genetic resources is being used as a formal submission to the Plant Treaty in contribution to current negotiations for the potential expansion of scope and membership.
The PhD was supported by the initiative “Adapting Agriculture to Climate Change: Collecting, Protecting and Preparing Crop Wild Relatives” which is supported by the Government of Norway. The project is managed by the Global Crop Diversity Trust with the Millennium Seed Bank of the Royal Botanic Gardens, Kew, UK, and implemented in partnership with national and international genebanks and plant breeding institutes around the world.