Natural variation meets changing environment

In addition to our green fields and pastures, we will have to use land and natural environments that have thus far remained untouched if we are to feed everyone on earth. There is very little increase in the yield of existing crops on ‘ideal’ land and certainly not enough to feed the projected nine billion world inhabitants by 2050. Furthermore, many crops are not resistant to plagues in the long term. The commercially attractive banana varieties, for example, are exceptionally vulnerable to Panama disease, which is a very difficult to control disease. Moreover, the conditions in many regions are altering due, for instance, to climate change and the associated extreme weather types. Cultivation of new land and regions that were previously deemed too dry, too saline, too deficient, too cold, or too hot requires plant varieties and animal species that can thrive in more extreme conditions. The question is whether there is a silver bullet, a jack-of-all-trades. Evolutionary biologists, (quantitative) geneticists, and statisticians and mathematicians, united in the Wageningen research groups Genetics and Biometrics, do not think so. They believe that it is mainly natural diversity which will have to facilitate the required global production increase.

In the selection of plants and animals, biologists, agriculturalists and geneticists nowadays look mainly at the interaction between genes and the environment. For a long time, the agricultural system was focused on strengthening the ‘positive’ elements of known varieties. Traditional breeding was aimed at achieving the highest possible yields. Practical factors were also important in the history of domestication. Crossbreeding, for instance, led to the development of grain varieties with higher yields because of a relatively short, thick stem. As a positive side effect, and additionally increasing yields, these varieties also much better survive bad weather at the end of the growth season. For a long time, European agricultural policy was also focused on growth in scale and uniformity. Now it seems that things are changing with a greater focus on regional variation, which is in turn creating opportunities for gene-environment research.

Mapping genomes

Fundamental knowledge of genetics became part of breeding a relatively short time ago. Now that scientists have mapped the genomes of certain crops, they can also find out which genes play a part in growth, plague resistance, nutrient intake, resistance to drought and more. With this knowledge they can make better choices and develop agricultural crops for land that has remained unused so far. This has led to a search for the mechanisms behind the successes and failures in agriculture.

The importance of plant and animal environments is shown in a number of practical cases. Dutch dairy cows only produced a fraction of the expected milk when they were introduced in Brazil. A European plant that colonised the United States thrived there in the absence of natural enemies, but turned out to have neglected its resistance against these pathogens and did worse than its immediate ancestors. The relevance of origins is also a factor for ‘our’ potato; the required pathogen and plague resistance was found in its ancestors from South America. The relative strength of plants can often be explained at the genetic level. This is where the plant holds the possibilities for adapting to new conditions and, therefore, the key to success or failure. The evolutionary biological research of the Laboratory of genetics led by professor Bas Zwaan, is performed in three ways. Initially, scientists select a generally occurring plant as model organism (Arabidopsis thaliana L., or thale cress). They look at the differences in genetic characteristics of the types that thrive in various environments to determine the relationship between genome and surrounding factors. In the second approach, they study the characteristics of plants that have fully adapted to extreme conditions. For this they for instance use Alpine pennycress (Thlaspi cearulescens J. Presl & C. Presl), which is related to thale cress as a model organism, allowing them to find the genes that make the plant suitable to the environment (and vice versa). With this type of research they can also discover the general mechanisms of, drought, salt or metal tolerance in plants. The third line of research uses selection experiments and experimental evolution with rapidly reproducing micro-organisms and insects to find the – often complex – mechanisms involved in adaptation to strange environments. These studies provide fundamental insights into the causes and limitations of adaptation that are also relevant to plant and animal breeding, biotechnology, and conservation biology.

Smaller ecological footprint

The idea behind the three developments is the same: Achieving a higher yield with a lower input of scarce resources such as energy and nutrients, and limited use of pesticides. Thus, argiculture with a much smaller ecological footprint. ‘More with less’ can be achieved by looking for the best, most adapted variety or species per environment. This can very possibly be attained by exploiting natural genetic variation, tried and tested over millions of years of evolution. However, adding new genetic variation via genetic modification and/or from different plant varieties can sometimes just give the push breeding needs to develop more efficient varieties. This differs from the traditional GMO development that was largely characterised by the previous desire to strengthen the classic success factor of ‘yield’. Since there is no such thing as a free lunch, there will always be trade-offs between characteristics such as growth speed, tolerance, weather resistance and resistance against plagues, as well as individual and group success.

The value of this Wageningen research is its contribution to the growing variation of (food) crops. It is already shedding light on genetic resources that are only visible at the genome level. It shows how crossbreeding can result in varieties that are better adapted to specific environments and which can therefore provide the solution to local problems as a result of issues such as climate change. Breeders have already embraced the philosophy regarding the relationship between genes and environment. They test promising crops and varieties in various countries to see how well they fare in those specific conditions. Preferably, they would like to find a variety that they can sell in as many countries as possible and in emerging economies. Nonetheless, niche markets where specific variations have proven their value are also becoming more relevant.