Crop wild relatives

Crop wild relatives (CWR) are wild plant taxa that have an indirect use as gene donors for crop improvement due to their relatively close genetic relationship to crops and the broader genetic variation they contain (Tanksley and McCouch 1997, Maxted et al. 2006). They have been increasingly used in plant breeding since the early 20th century — for example, to confer resistance to pests and diseases, improve tolerance to environmental conditions such as extreme temperatures, drought and flooding, and to improve nutrition, flavour, colour, texture and handling qualities (see Hajjar and Hodgkin 2007, Maxted and Kell 2009, Dempewolf et al. 2017 for reviews). The economic value of CWR is estimated as approximately 30% of modern crop production increase and has an annual value of approximately US $115 billion worldwide (Pimentel et al. 1997). Conserving CWR diversity is, therefore, critical to ensure food, nutrition and economic security. This is especially true in a global scenario in which the climate is changing, human population is exponentially increasing, agriculture is being practised in more marginal environments and future agriculture production is predicted not to be able to mitigate these challenges without the input of the broader range of traits found in CWR taxa. These species, like any other wild plant species, are currently threatened. Not only because whole species are becoming extinct, but also because the genetic diversity within extant CWR is seriously being reduced. In spite of this, CWR are currently poorly conserved. Although some of their populations are found within existing protected areas, in most cases they are not monitored or actively managed. Consequently, very few genetic reserves have been established to actively conserve CWR in the wild. On the other hand, ex situ conservation (outside their wild habitats, in gene banks) remains insufficient (Castañeda-Álavarez et al. 2016).

The conservation of CWR within existing protected areas is particularly important, not only because these areas are already formally recognized, but because such conservation promotes continued evolution alongside pests and diseases and in changing environments. As a site manager, it can be important to adapt the management plans of your site to incorporate CWR targeted conservation actions. In fact, a joint notification of the CBD/ITPGRFA/CGRFA/Bioversity (published in August 2015) called for the “strengthening [of] the in situ conservation of PGRFA [Plant Genetic Resources for Food and Agriculture] through incorporation of CWR under areas important for biodiversity in protected area networks and other effective area-based conservation measures”.

In order to help you identify sites to actively conserve priority CWR in situ (as well as areas for collecting ex situ, develop CWR checklists, CWR prioritization for conservation, etc.) an 'Interactive Toolkit for CWR Conservation Planning’ was developed. It aims at guiding users through the various steps involved in CWR conservation planning by providing detailed methodologies and interactive flowcharts that help the user move through the various components and choose the options that are most appropriate in the user’s national context, but also showing numerous examples and resources to help the user to undertake each particular step in conservation planning (Magos Brehm et al. 2007).

Links to additional information

  • Castañeda-Álvarez NP, Khoury CK, Achicanoy HA, Bernau V, Dempewolf H, Eastwood RJ, Guarino L, Harker RH, Jarvis A, Maxted N, Müller JV, Ramirez-Villegas J, Sosa CC, Struik PC, Vincent H and Toll J (2016) Global conservation priorities for crop wild relatives. Nature Plants 2: 16022. doi:10.1038/nplants.2016.22.
  • Dempewolf H, Baute G, Anderson J, Kilian B, Smith C and Guarino L (2017) Past and Future Use of Wild Relatives in Crop Breeding. Crop Science 57:1–13.
  • Hajjar R and Hodgkin T (2007) The use of wild relatives in crop improvement: a survey of developments over the last 20 years. Euphytica (1–2): 1–13.
  • Magos Brehm J, Kell S, Thormann I, Gaisberger H, Dulloo E and Maxted N (2017) Interactive Toolkit for Crop Wild Relative Conservation Planning version 1.0. University of Birmingham, Birmingham, UK and Bioversity International, Rome, Italy. Available at: http://www.cropwildrelatives.org/conservation-toolkit/.
  • Maxted N and Kell S (2009) Establishment of a Network for the In Situ Conservation of Crop Wild Relatives: Status and Needs. Commission on Genetic Resources for Food and Agriculture. Food and Agriculture Organization of the United Nations, Rome, Italy. Available at: http://www.fao.org/docrep/013/i1500e/i1500e18a.pdf.
  • Maxted N, Ford‐Lloyd BV, Jury S, Kell SP and Scholten MA (2006) Towards a definition of a crop wild relative. Biodiversity and Conservation 15(8): 2673–2685.
  • Pimentel D, Wilson C, McCullum C, Huang R, Dwen P, Flack J, Tran Q, Saltman T and Cliff B (1997) Economic and environmental benefits of biodiversity. BioScience 47: 747–757.
  • PwC (2013) Crop Wild Relatives. A Valuable Resource for Crop Development. PricewaterhouseCoopers. Available at: http://pwc.blogs.com/files/pwc-seed-bank-analysis-for-msb-0713.pdf.
  • Tanksley SD and McCouch SR (1997) Seed banks and molecular maps: unlocking genetic potential from the wild. Science 277(5329): 1063–1066.
Wild pear