Adapting agriculture to climate change
Adapting agriculture to climate change is one of the most urgent challenges of our time. To meet this challenge we are turning to the wild cousins of the crops we eat for their useful traits which have the power to safeguard our future food security.
Wild Carrot growing in Youghal, Ireland (Photo: Ruth Eastwood, RBG Kew)
Adapting agriculture to climate change
The 'Turn Down the Heat' reports recently published by the World Bank predict that a 2°C rise in temperature by 2050 could reduce crop production in Sub-Saharan Africa by 10%. Rising temperatures, changes in rainfall, erratic weather patterns and the prevalence of pests and diseases resulting from climate change threaten agricultural productivity and therefore undermine global food security. This, coupled with the pressures of human population increase, will mean that the demand for food will be greater than ever.
Since the dawn of agriculture, over 10,000 years ago, humans have been selectively breeding plants based on characteristics such as taste, high yield, resistance to disease, growing conditions and easy harvesting. Even though there are around 7000 species of food crops globally, only 12 of these account for approximately 80% of global consumption. While the domestication of plants has allowed human population growth and the development of society, the subsequent loss of genetic diversity has left the crops vulnerable to pests, diseases and changing environmental conditions.
The Irish potato famine of the 1840s is a harrowing example of what can happen when we do not maintain a certain degree of genetic variability in our crop species. At that time Ireland was dependent on only a few varieties of potato, none of which contained resistance to Late Blight, a disease caused by a fungus, which leaves potatoes rotten and completely inedible. In 1845 when Late Blight struck, a million people starved to death and millions more emigrated to unaffected areas. The social and economic consequences of a famine are devastating and the poor are always the first to be affected. Genetic diversity is the key to resilience against such threats and the best source of genetic variation can be found in the wild relatives of crop species. The Sárpo varieties developed in the 1950s by Dr Istavaán are the most blight resistant potatoes available today. Their resistance can be traced back to genes found in crop wild relative Solanum demissum collected in the ancestral home of the crop, Central and South America.
Crops for our future
Crop wild relatives can be defined as wild plant species which are genetically related to the crop but, unlike the crop, they have not been domesticated. This definition also includes ancestors of the crop. Crop wild relatives serve as a genetic back-up. They have a much broader genetic base than crop species because they have not been subjected to the genetic bottleneck that comes with domestication, and therefore they are more likely to survive the challenges that come with climate change. Advanced screening techniques allow breeders to identify which plants have desirable traits, so that these plants can then be used in breeding programs and their useful characteristics can be passed onto the crop.
Rice is particularly vulnerable to temperature increases because it is sterile at temperatures above 32°C. Fortunately, scientists in Japan have introduced an early morning flowering trait from crop wild relative, Oryza officinalis, into the cultivated variety. By flowering in the morning when it is cooler it is hoped this variety will mitigate predicted yield losses due to climate change (Ishimaru et al. 2010).
Protecting and using crop wild relatives
Many crop wild relatives are in danger of extinction from habitat degradation, soil erosion and changes in environmental conditions. Furthermore, these wild cousins of our crops remain largely uncollected and therefore they are largely unevaluated and unavailable for plant breeders and farmers. It is vitally important, and in the interests of humanity, that we harness the genetic potential found in crop wild relatives, for the improvement of our crops.
The Millennium Seed Bank in collaboration with the Global Crop Diversity Trust is engaged in a project called ‘Adapting agriculture to climate change’. The main objective of this project is to collect, protect and prepare the wild relatives of the world’s most important food crops, in a form that plant breeders can readily use to produce varieties adapted to future climatic conditions that farmers in the developing world will soon be encountering.
The project focuses on the wild relatives of 29 crops which are of major importance to food security, covered by Annex 1 of the International Treaty of Plant Genetic Resources for Food and Agriculture. The crops are African rice, alfalfa, apple, aubergine, bambara groundnut, banana, barley, bread wheat, butter bean, carrot, chickpea, common bean, cowpea, faba bean, finger millet, grasspea, lentil, oat, pea, pearl millet, pigeon pea, plantain, potato, rice, rye, sorghum, sunflower, sweet potato and vetch. To find out more about the wild relatives of these and other crops visit the Crop Wild Relatives and Diversity website.
The project aims to:
- Identify those crop wild relatives that are missing from existing collections, are most likely to contain diversity of value to adapting agriculture to climate change, and are most endangered
- Collect them from the wild
- Provide them to genebanks for conservation
- Prepare these and others already in collections (‘pre-breeding’) for use in breeding crops for new climates
- Evaluate them for useful traits, and
- Make the resulting information widely available
To date the project has:
- Developed the Harlan and de Wet inventory
- Undertaken a gap analysis of CWR in genebanks worldwide
- Initiated discussions with potential collecting countries to support in-country CWR collecting
There is, quite simply, no more important step we can take to prepare for climate change than to ensure that the crops that feed humanity are adapted to deal with the current and future challenges of climate change.
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