This periodic blog will discuss food security, with a specific focus on how plant genetic research might contribute to addressing the challenge of feeding a fast-growing global population in increasingly uncertain climatic conditions.
Achieving food security is a complex problem that goes far beyond just producing more food. Its realisation will require deep transformations of food systems, and for many, it will also mean fundamentally changing our relationship with food.
THE (SHRINKING) GARDEN OF EARTHLY DELIGHTS
There are more than 350,000 different plant species in the world, and about 50,000 of these are suitable for human consumption. However, only 300 or so ever make it to a market or kitchen, and just 12 provide three-quarters of all food and feed. Of these major crops, a handful of super crops dominate: sugar cane tops the ranking with 1.9 billion tonnes produced globally in 2013, followed by the three big cereals: maize of which 1 billion tonnes were produced in 2013, then rice and wheat of which just over 700 million tonnes each were produced in the same year (FAOSTAT). There are also a handful of globally important energy-rich crops including sugar beet, soybean, sunflower, oilseed rape and oil palm. All these commodity crops are widely traded in international markets.This is a relatively recent trend: 100 years ago diets were more diverse and characterised by a higher consumption of locally important grains and vegetables. The biggest difference in national diets have occurred in Sub-Saharan Africa, and in East and Southeast Asia. The United Nations Food and Agriculture Organization (FAO) estimates that in the last century about 75 per cent of the diversity in farmers’ fields has been lost. It also predicts that climate change may wipe out more than 20 per cent of the wild relatives of important food crops.
Curiously, at the national level diets are more varied and people rely on a higher number of species – the problem, however, is that these are the same species everywhere in the world.The homogenisation of the contents of our plates has been accompanied by another trend: portions are getting bigger. We eat on average more in terms of overall calories and also consume a higher proportion of fat and proteins. Obesity and non-communicable diseases associated with over-eating are now global public health challenges.
And there are more problems…
Connectivity, cheaper food… and shared vulnerability
The heavy reliance on a handful of crops that are widely traded in international markets with large volumes of exports means that the interconnectedness and interdependence among countries for their food supplies is very high. For example, between 1992-2009 the number of global wheat and rice trade connections doubled and trade flows increased by 42 and 90 per cent, respectively. The current system evolved as a result of the Green Revolution, which involved the development of high-yielding varieties of cereals that responded well to irrigation and to the addition of chemical inputs, especially fertilisers. It has economic advantages: yields can be very high, and major commodities produced cheaply in some countries and then exported to others. Between 1980 and 2000 the real price of wheat and rice halved, and the price of sugar dropped about fivefold. Alas, the benefits of the Green Revolution did not extend to all the regions to the world, in particular missing Sub-Saharan Africa.
The current system is also intrinsically vulnerable. Eighty-five per cent of countries have low or marginal food self-sufficiency, which means that shocks in major food producing areas, such as unfavourable weather conditions, can be felt globally and have very serious effects.
The loss of diversity also makes agricultural systems more vulnerable to the effects of pests and diseases. A telling example is wheat stem rust: Ug99 is a strain of the fungal disease that can result in complete loss if it affects a crop early in the season. It has contributed significantly to painful hikes in wheat prices. Nick-named ‘wheat’s worst enemy’ and a ‘time-bomb’, Ug99 is extremely aggressive, being virulent on 90 per cent of all tested wheat varieties. Ug99 was first identified in Uganda in 1999, and the disease is both spreading fast and mutating rapidly. Since wheat provides 20 per cent of the calories consumed by humans every day, the effects of the disease spreading to the world’s bread baskets in Central Asia and North America are potentially catastrophic. Combating stem rust is justly considered a global priority. In general efforts to tackle and contain emerging plant pests and diseases are critical for food security.
This dependence between countries also extends to crop genetic diversity, since centres of biodiversity do not coincide with major production areas. On average, 68.7 per cent of the diet of an country, and 69.3 percent of national agricultural production systems, depend on crops whose genetic diversity originates largely outside their borders (Map 1). Map 2 shows the degree of dependence of a country on crops whose genetic diversity originates from outside their borders .
Safety in diversity
Crop diversification to safeguard global food supplies is important for a number of reasons. The main commodity crops have been bred to perform well under high input management schemes, with a high use of fertilisers, chemical controls and irrigation, so they tend to score low on sustainability. In addition, crop characteristics linked to resilience – the ability to yield in marginal and low-input environments – may have been lost during the breeding process. The reason for this is that breeders have, for example, selected for the combination of alleles (alternate forms of genes) that allows the crop to respond well to fertilsers rather than for those combinations that help the plant to better use the nutrients in soils with reduced fertility. And some traditional crop species also perform better in conditions of drought, flooding, temperature extremes, and pests and diseases than current major staples. For example, recent work has shown that pearl millet copes better with drought because it is able to absorb less salt from the soil – high levels of salt in soils is another important limitation to production in many parts of the world. Building lost diversity back into our diets will also improve nutrition, since a varied diet is the best way of ensuring a balanced diet. One of the main reasons for malnutrition is that poor people often obtain most of their calories from one cheap staple crop, such as rice, which is low in proteins, iron and vitamin A.
Traditional crops are sometimes referred as underutilised species, neglected or orphan crops, mainly because of the lack of resources invested in them in the last decades. Underutilised species will be the focus of the next blog.
Dr Claudia Canales Holzeis is a plant molecular biologist with a near-decade of experience in plant genetics research. She previously worked as Senior Project Officer for the International Service for the Acquisition of Agri-Biotech Applications (ISAAA), based in the Philippines. A graduate of the University of Reading in Environmental Biology, Dr.Canales gained a DPhil. in Plant Genetics at Oxford.