Crop wild relatives (CWRs) are wild plant species that are genetically related to our cultivated crops. Farmers have used them since the beginning of agriculture to improve their crops and get better harvests.
Growing in the wild, they contain higher genetic diversity and are a source of genetic material for farmers and breeders who can cross breed them with cultivated varieties.
This type of cross breeding is important to food security, for example, by reducing the risk of crop failure: useful traits that are found in crop wild relatives include better resistance against pests and diseases, or tolerance to environmental stresses.
Just like any other plant species, crop wild relatives can be vulnerable to changes, such as the destruction of their habitat, climate change and pollution. CWRs can be conserved in two ways. They can be stored in gene banks, where seeds and other plant parts are securely held, and the risk of losing valuable genetic material is low. This is known as ex situ conservation, the process of protecting plant or animal species outside of their natural habitat. However, this is not enough, as pests and diseases and environmental conditions keep changing. It is important to conserve them also in their natural habitats, or in situ, where they can continue to evolve.
The need to protect crop wild relatives is generally recognised: Aichi Target 13 (Convention on Biological Diversity) foresees the development of strategies to safeguard the genetic diversity of cultivated plants and their wild relatives, while the Scottish Biodiversity Strategy’s 2020 Challenge sees the genetic diversity of cultivated crops and their relatives as an important element of Scotland’s natural capital.
However, as in many other countries around the world, action to protect CWRs in their own right has been limited. Hannah Fielder, from Birmingham University, carried out research for her PhD on the conservation of CWRs in the UK, including a focus on conservation at devolved level, both in situ and ex situ. She identified a list of 120 priority CWRs which should be conserved in Scotland, based on their usefulness for plant breeding and how threatened these plants are.
Through a spatial analysis of records of these plant species in Scotland, Hannah identified a number of hotspots and where these hotspots overlap with protected places. Of these 120 priority CWRs, only 15 are represented in ex situ collections at Aberystwyth University’s Genetic Resources Unit, and at the Millennium Seed Bank in Kew. This highlights the need for more collection work in the field.
SNH has contributed to this work by providing advice to Hannah during her studies, and by co-authoring two journal articles. For more detailed information on CWRs you can read the first of these articles which has just been published online – Enhancing the conservation of crop wild relatives in Scotland.