European Crop Wild Relative Diversity Assessment and Conservation Forum


Crop wild relative species



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What is a crop wild relative?

A crop wild relative (CWR) is a taxon related to a species of direct socio-economic importance.  Socio-economically important species include food, fodder and forage crops, medicinal plants, condiments, ornamental and forestry species, as well as plants used for industrial purposes, such as oils and fibres.  Results of data analysis carried out by PGR Forum show that approximately 79% of the Euro-Mediterranean (Europe plus the Mediterranean) flora consists of crop wild relatives and other utilised species, as well as the crops themselves; in other words, more than three-quarters of the plant species in the region have a current or potential direct use to humankind. 


A formal definition of a crop wild relative has been proposed by Maxted et al., (2006): "A crop wild relative is a wild plant taxon that has an indirect use derived from its relatively close genetic relationship to a crop; this relationship is defined in terms of the CWR belonging to gene pools 1 or 2, or taxon groups 1 to 4 of the crop".  (Taxon group 1 (TG1) = taxa within the same species; TG2 = taxa within the same section or series; TG3 = taxa within the same subgenus; TG4 = taxa within the same genus; TG5 = taxa in different but related genera).   Maxted et al. have found that for many taxa where genetic information is available, the taxon group concept correlates very closely with the gene pool concept.  Thus, in the absence of genetic data on the crop gene pool, the taxon group concept provides an alternative and effective means of assessing the genetic relatedness of CWR to crops. To read further information about the taxon group concept, click here.


Reference: Maxted, N., Ford-Lloyd, B.V., Jury, S.L., Kell, S.P. and Scholten, M.A. (2006). Towards a definition of a crop wild relative. Biodiversity and Conservation 15(8):2673-2685.


Why are crop wild relatives important?

Crop wild relatives are essential components of natural and semi-natural habitats, as well as agricultural systems, and are critical for maintaining ecosystem health.  Their conservation and sustainable use is vital for improving agricultural production, increasing food security, and maintaining the environment.  


N.I. Vavilov realized the importance of crop wild relatives in the early years of the 20th century, particularly in their ability to exchange genes with the crops themselves.  Crop wild relative germplasm (genetic material) has been utilised by humankind for thousands of years to improve the quality and yield of crops.  Natural crosses between crops and their wild relatives have occurred since the beginnings of agriculture.  Farmers have used traditional breeding methods for millennia, and more recently, plant breeders have utilised crop wild relative genes to improve a wide range of crops, including wheat (Triticum aestivum), maize (Zea mays), rice (Oryza sativa), barley (Hordeum vulgare), potato (Solanum tuberosum), cassava (Manihot esculenta), and grain legumes such as Phaseolus, Vicia, Vigna, Lens, Lathyrus, and Cicer.  Improvements include resistance to pests and diseases, and abiotic stresses, such as drought and salinity.  Other uses include increased protein and vitamin content, and the improvement of medicinal plants and pharmaceuticals.


Europe is an important centre for crop wild relative diversity.  Major crops such as oats (Avena sativa), sugar beet (Beta vulgaris), apple (Malus domestica), annual meadow grass (Festuca pratensis), and white clover (Trifolium repens), have wild relatives in Europe.  Many minor crops have also been developed and domesticated in the region; such as arnica (Arnica montana), asparagus (Asparagus officinalis), lettuce (Lactuca sativa), and sage (Salvia officinalis). 


Although it is acknowledged that populations of crop wild relatives throughout Europe are under threat from habitat alteration and loss, their conservation across the region has received relatively little systematic attention.  There are a number of initiatives to inventory European crop wild relative species at the individual country level, but there has previously not been a coordinated effort focussing on the production of a comprehensive European online CWR  catalogue.  And while some European crop wild relative material is conserved ex situ, their conservation in situ has not been the subject of significant debate.


The PGR Forum CWR Catalogue for Europe and the Mediterranean

The PGR Forum CWR Catalogue for Europe and Mediterranean has been produced through a process of data mining and analysis using a number of databases, primarily Euro+Med PlantBase and Mansfeld's World Database of Agricultural and Horticultural Crops.  Access to the catalogue is available at:


The PGR Forum Crop Wild Relative Information System (CWRIS)

PGR Forum has created an information system to provide access to European and Mediterranean crop wild relative data (the PGR Forum Crop Wild Relative Information System - CWRIS).  CWRIS, incorporating the PGR Forum CWR Catalogue for Europe and the Mediterranean, includes all socio-economically important species occurring in Europe and the Mediterranean and their wild relatives; including food, fodder and forage, medicinal plants, condiments, ornamentals, forestry species, as well as plants used for industrial purposes, such as oils and fibres.


CWRIS is available for consultation at:


The PGR Forum logo

The project logo represents the wild ancestor of the olive, Olea Europaea subsp. oleaster.  Olives have been cultivated in Europe and the Mediterranean for centuries and are extremely important for the regional economy.  The wild olive grows in maquis and woodland throughout the Mediterranean region, and is distinguished from the cultivated form by its shrubby habit, spiny stems, smaller leaves and small bitter fruits.  In many countries, wild olives are sparse or even rare. The plant is therefore a potent symbol both as a highly important genetic resource and as a species of conservation concern.


The logo was designed and produced by Margaret Chamberlain and Ian Dicks, graphic designers and illustrators.


Copyright � University of Birmingham 2003�2005. All rights reserved.

The University of Birmingham hosts and administers this web site on behalf of the European crop wild relative diversity assessment and conservation forum (PGR Forum)


Page last updated 23 October 2006


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