Biodiversity, genetic diversity and food security by Jim Peacock, CSIRO Plant Industry, Canberra

The world faces a huge and critical problem - to provide a reliable food supply for a further three billion people in the next 25 years. The constraints for the achievement of this objective are also of major dimension. The increased production has to come from the present area of agricultural land, and preferably from a reduced area, with farming ideally being retracted from some of the marginal lands currently being used. A second constraint, which has arisen as a consequence of societal pressures but is of biological necessity for the security of food supply, is that the farming systems should be sustainable and not progressively detrimental to the limited natural resource.

Our food production rests predominantly on only a few plant and animal species, a tiny fraction of the array of biodiversity in our world. Biodiversity of natural ecosystems must be preserved - they are the maintenance and service providers for global environmental health. Destruction of ecosystem habitats are largely a consequence of urbanisation, desertification and deforestation and these must be controlled in all parts of the world.

FAO/Prayoon Amaree

FAO/Prayoon Amaree

Biodiversity is also important in the agricultural production ecosystems and involves genetic diversity in the production species themselves but also refers to the huge array of attendant species which pollinate crops, maintain soil structure and composition and facilitate the acquisition by plants of essential minerals and ions from the soils. Natural ecosystem and agricultural ecosystem biodiversity are often confused. Both are important but they are different. We must strive to manage the production lands so that they have minimal effect on natural ecosystems, which, apart from their intrinsic values, supply the production lands with critical resources such as water supply, water quality and provide buffering conditions against a range of natural disasters.

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Plant breeders have forged the varieties we use on our farms by continually selecting the heritable variation that provides desired traits and characteristics. The increasing yields of farm varieties over the past several thousand years are testament to the skills of farmers and breeders in recognising and incorporating advantageous changes into the genetic make-up of our production species.

Farmers have in the past, and still do, play a role in the husbanding of the diversity in crop species, but their role has been supplemented by the establishment of excellent and comprehensive genetic resource infrastructure, globally distributed, and by the development of broad-based breeding programs. Breeders have met many of the challenges of the environment and of pests and diseases through increasingly effective plant improvement programs, but it is the intensive agriculture of developed countries that has benefited most from genetic adjustments. However, International Agricultural Programs have made significant contributions to the performance of crops in developing countries.

THE NEW PLANT SCIENCE

Are the current International Agricultural programs able to cope with the problems and demands of third world agriculture and for the significantly increasing demands of the future? I don’t believe that we will meet the needs of the future if we proceed as we are - the status quo. There are powerful new developments in Biology and in Agriculture. Plant science was transformed in December 2000 when the complete genetic sequence of a plant species, Arabidopsis thaliana, was published. Prior to that time, research had already disclosed a lot of the basic facts about genes and the way in which information was coded along the DNA molecule to provide for the manufacture of gene products, the enzymes and proteins needed for the structure and functioning of a plant. It was recognised that in addition to the gene product code there were coded motifs which provided the basis for the controlled working of each gene. Having the complete sequence of Arabidopsis meant that we had the complete dictionary of the gene words of that plant species. Most plants have a basically similar dictionary of genes. By the end of 2002 most of the gene words of the rice plant had been worked out and a number of other species are on the way.

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USDA

USDA

But a dictionary of words is not very useful if there are no meanings attached to the words. One of the highly impressive developments of plant science in the last three or four years has been the way in which international collaboration between laboratories has led to an understanding of the function of many of the genes. This is absolutely critical for modern plant improvement programs. We are now able to understand the practical challenges and needs of crops in the field in terms of what gene functions need to be put into place or changed to improve crop performance. We have been able already, with the modifications even of single genes, to provide major advances to some breeding programs. We have also been able to discern the way in which genes interact, and have already been able to construct simple, functional genetic sentences, involving a number of genes working together to provide protection against diseases, against drought, low temperatures, or in providing new quality characteristics in the harvested products.

We are, admittedly, at the dawn in our ability to selectively rewrite the book of life for the plants on which we are absolutely dependent for our food supply. Will our new understanding of the processes of plant development and function, provide for the necessary significant increases in yields and sustainability of our food production systems? There are no magic bullets but I am absolutely certain we can be positive. Not all the new developments will result in genetically modified crops (GMOs). In many cases research using the new technologies will provide new objectives and new enabling technologies, increasing the power and speed of conventional plant breeding.

POWERFUL NEW PLANT BREEDING

Even though over the centuries plant breeders have made spectacular improvements to our production plants, we tend to be conservative in defining the objectives and the technologies of plant breeding. One of the absolutely spectacular examples of why we must accept change in the way we go about some of our plant improvement programs has come from the use of a sophisticated chemical instrument, the mass-spectrometer, in producing wheat plants which have, through an increase in their efficiency of including both the heavy and light natural isotopes of carbon from the atmosphere into the products of photosynthesis, significant increases in yield per available units of water supply.

Using the powerful new technologies, we are now understanding, in much greater depth, some of the key processes that a plant uses to grow and function. One of the major unpleasant facts of our existing production lands is that sizeable areas are less than ideal for plant growth. For example, it has been estimated there are more than 800 million hectares, some 6% of arable lands, that are challenged either by saline or sodic conditions. Most of our crop plants suffer from reduced yields or are incapable of growing in some of these areas. We now know mechanisms by which evolution has equipped some plants to cope with these conditions, either by excluding sodium ions from entry to the root system or by transporting any sodium that has entered the plant’s system into vacuole storages where it does the plant no harm at all. Laboratories around the world have been able to identify some of the responsible genes. Enhancement of the salinity tolerance of tetraploid wheat has been achieved by a breeding program which has transferred, from an ancestral Durum landrace into modern cultivars, genes which provide spectacular increases in tolerance to saline conditions. We have every reason to expect, even though there are hundreds of genes which need to be operating to give overall salinity tolerance, that these key genes will be of major consequence in improving the performance of most of our production species, particularly the cereals.

Of even greater dimension is the 40% of arable land which has acid soils, reducing yield and survival of crop plants. A wonderful example of a single gene modification which has converted acid-susceptible barley to acid soil tolerant barley, is the introduction of a wheat aluminium toxicity tolerance gene into the genetic make-up of barley. This highly directed and simple use of existing genetic diversity can be expected to have significant positive effects on crops in acid soil regions until such time as farmers are able to afford the reparation steps needed to revert the acid soils to a balanced, healthy soil resource.

PESTS AND DISEASE - DETRIMENTAL COMPONENTS OF BIODIVERSITY

The examples of the achievement of better performance of plants under challenging conditions of natural resources are spectacular. They add up to big slices of the needed increase in food production when fully applied to the various agricultural systems, and of course we can expect many other such improvements. But I suppose the most spectacular examples of the new agriculture are those given by the protection of plants against biotic challenges. There is enormous excitement and lifts of knowledge in the area of host pathogen interaction. For example we have been able to harness a naturally existing molecular mechanism in plants to generate immunity against specified viruses that have otherwise been unapproachable by plant breeding. But the protection system that I want to discuss a little more fully is that provided by insect-proofing genes, my example being Bt protection in cotton in Australia. This example emphasises a point which has importance for all plant improvement. Improved performance as a result of new genetic diversity is not enough in itself, it must be accompanied by well researched and developed management systems. In the case of the insect proofing of cotton, the accompanying management and agronomic practices are highly significant Lack of attention to these practices could spell doom to the new, powerful technology. The integrated introduction of the new insect-proofing genes and the new management strategies represent one of the best examples of the approach that we must achieve now in all agricultural systems whether they be in developing countries or in the sophisticated high input systems of countries like Australia.

If the conventional cotton varieties are not protected with insecticides, crop yields amount to nothing. Resistance to the available insecticides was making it likely that the whole industry could disappear in Australia. The addition of the Bt gene construct to our cotton, initially a single gene, reduced the need for pesticide applications by some 60%, generating a positive environmental outcome and increased profits for the farmer. This season we have the widespread adoption of cotton with two insect-proofing genes operating in independent molecular modes. We are expecting an 85% reduction in the use of insecticides. Together with the recommended management systems we have, for the first time in our country, the basis for integrated pest management and the establishment of a sustainable industry.

FOOD QUALITY TRAITS

M.S. Swaminathan has said “The right to food needs to become the right to good food”. The new developments in plant science are providing the means by which substantial improvements in the nutritional qualities of plant foods can be made. For example it has only been recognised in recent years that diabetes is one of the major causes of poor health and death in many developing countries, where the incidence of diabetes is increasing just as rapidly, if not more rapidly, than it is in developed countries. More than 80% of the 300 million sufferers that we can expect in 2025 will be people of developing countries and it is highly likely that this estimate is a gross underestimate.

Diabetes effects people primarily in their productive working years so it generates a huge economic burden over and above the burden to the individual. We can now design the staple food plants of developing country populations to have starch of low glycaemic index, a property of enormous advantage in the prevention and minimisation of the effects of the pre-diabetic and diabetic conditions.

Other changes can be made to starch composition to ensure a high proportion of resistant starch, a property that will enhance colonic health and which is shown to be of positive value in oral rehydration therapy in the treatment of diarrhoea resulting from infectious diseases. We have identified genes controlling the level of amylose and resistant starch in barley and have already conducted successful animal and human trials showing the modified starch composition is providing nutritional and health gains.

A range of other changes in the composition of plant foods can be made. Most of these will be achieved through the new enabling technologies associated with conventional breeding programs. We can expect to increase protein content, to provide proteins with balanced amino acid composition; we can adjust seed lipids to optimum composition for human health and we can expect to overcome micronutrient deficiencies and increase the bio availability of needed vitamins and other health-generating molecules.

EFFECTIVE DELIVERY OF NEW GENERATION VARIETIES

I have made the case that genetic diversity holds the key to increased food production and increased security of food production. Because plant breeding provides new performance and quality traits in a sophisticated farmer-friendly package, the seed, the new plant science can make contributions to subsistence farming, to low input farming and to the higher input farming in developing countries as well as to the major agricultural systems of the western world.

Although some of the examples I have discussed represent adjustment of the genetic system of a crop species without the addition of genetic diversity from other plants, a number of them demonstrate that the source of genetic diversity can now extend far beyond the direct gene pool of the crop species itself. This emphasises the critical importance of biodiversity and its intimate relation with genetic diversity of the production species. A major advantage of the new breeding methodologies is the reduced lag between recognition of a problem and the release of varieties providing an in-built answer to the problem. The plant breeder will have faster ways to produce a new cultivar.

I must reemphasise that the new level of understanding of plant development and function at the molecular level does not only provide for plant improvement through GMOs. One of the most exciting properties of the new plant science in its translation into the new agriculture is the integration of the new gene technologies into conventional breeding programs. There is discussion in many communities about GMOs, but the uncertainty is not based on factual evidence of hazard. There are already large production areas of GMO crops and these, over seven years, have not led to human health problems, to environmental damage or to economic disadvantage. If we adhere to strong regulatory systems then I believe, that where necessary, GMOs will have important, integrated roles in developing countries.

NECESSARY PARTNERSHIPS

Apart from the challenge of increased and secure food production, a further challenge for us, and it is a very real one, is to be able to change our delivery systems of improvements to the food plants in developing country agriculture. Not every agricultural research institute can be expected to be at the forefront of the new plant science. Nor should they be. We need to put into place systems where breeding institutes can work closely with the farming systems of developing countries but can also work closely with the laboratories which are able to take advantage of the new plant science. It is these partnerships which will enable us through out new agriculture, to meet the challenges of a secure food supply for the nine billion people of 2030, not only the supply of food but the supply of nutritionally-balanced food providing for better health in the human populations.

It takes courage to say Yes to a potential new technology when there is some element of uncertainty about it as there is about gene technology. But in the end, the seemingly safe decision of No may do irreparable and lasting harm to the human condition. If we fail to take advantage of the powerful and life-giving improvements that can be made to our food supply, and especially in developing countries and to subsistence farmers, then we will be guilty of not accepting the responsibility and opportunity to enhance the health and quality of life of more than a third of the world’s population. Model farmers - awards for outstanding achievements