Crop diversity


Barley Hordeum vulgare © Ita McCobb

Global crop diversity

The loss of biodiversity is one of today’s most serious environmental concerns. Experts have advised that protecting the diversity of the world’s crops is vital for ensuring global food security.

Among the many threatened plant species are wild relatives of global crops (Crop wild relatives, CWR), species that modern breeders and genetic engineers rely on to transfer beneficial traits to future crop varieties.

CWRs are wild plant species closely related to crops, which grow under a broad range of environmental conditions in their natural habitats and so are more genetically variable.

Their adaptive traits can be transferred to crops to improve tolerance to extreme environmental conditions, such as heavy rainfall or drought and exposure to different pests and diseases.

Wild genetic diversity is essential for protecting global crops such as wheat, barley, rice and beans from climate change, pests and environmental stress. It is also fundamental to defeating hunger and achieving food security.

Scientists believe that conserving the diversity of crop varieties is the only way to guarantee that farmers and plant breeders will have the raw materials needed to improve and adapt their crops to meet future challenges, in particular, providing food for the future.

Crop diversity is in danger of being lost if measures are not taken. Extending seed longevity in seed and gene banks is regarded as complementary to conserving plant species in situ in their natural environment (see Saving plant seeds).

As producers are relying on just a handful of the highest-yielding varieties of fruits, vegetables and grains, thousands of other varieties are disappearing at an alarming rate.

Scientists have warned that a loss of diversity means more people are dependent on key crops such as wheat, rice, potatoes and sugar, leaving them more exposed to harvest failures.

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Wheat CWR Aegilops tauschii © University of Birmingham, School of Biosciences

Crop wild relatives’ database

This is why scientists at the University of Birmingham have compiled the first database of CWR and their locations around the world. They have highlighted areas where many different types of CWR are concentrated and could be conserved to secure future global food resources.

A significant proportion, however, are found in conflict zones in the Middle East, where their conservation is increasingly threatened.

The area where CWR are most concentrated is in the so-called Fertile Crescent, which is situated in the Middle East curving around the Arabian desert from Jordan, Palestine, Israel, Syria, Lebanon and Turkey to Iraq and Iran.

Dr Nigel Maxted, lead investigator from the University of Birmingham’s School of Biosciences, said “There has previously been no opportunity to systematically conserve and use CWR as there was a lack of clarity over their identities and distribution. By creating an inventory of globally important CWR we can discover which countries and regions are the richest in terms of priority CWR, and more efficiently plan and coordinate conservation efforts to ensure their survival.

“It is very important that we conserve these species in secure gene banks, but it is critical to conserve them in their natural habitat so they continue to adapt to changes in climate as well as threats from pests and diseases,” he added.

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Wild carrot Daucus carota ssp carota © Ita McCobb

Wild plant species native to China

As well as identifying parts of the Middle East as an important area of CWR, scientists have also identified wild plant species native to China that have the potential to adapt and maintain globally important crops.

Many of these are threatened with extinction in China and require urgent conservation action. This includes wild relatives of certain crops that are globally threatened because they do not appear anywhere else in the world.Many of these are threatened with extinction in China and require urgent conservation action. This includes wild relatives of certain crops that are globally threatened because they do not appear anywhere else in the world.

Shelagh Kell, Research Fellow at the University of Birmingham’s School of Biosciences, said “China has remarkable wild plant diversity with more plant species than Europe and CWR of globally important food crops; however, urgent attention needs to be paid to its CWR ... so that this diversity is available for use in crop improvement programmes before it is lost.”

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Crop diversity table

European wild plant conservation

The University of Birmingham’s database shows that European conservation is not much further ahead. Dr Nigel Maxted said “Before we did this analysis, we didn’t realize there were so many crop wild relatives in southern Europe. You’d imagine that these areas would have been well collected.”

Countries in Europe with the highest diversity of species include Portugal, Bulgaria, Italy and Spain (see table).

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References: University of Birmingham;;; Clive Cookson, Tyler Shendruk, Financial Times, 19 September 2014.