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Heat beater beans

Klaus EsterlußMarch 31, 2015

The Consultative Group on International Agricultural Research (CGIAR) has discovered 30 types of heat-resistent beans. But how? An interview with Steve Beebe, senior bean researcher at CGIAR.

red beans (Photo: International Center for Tropical Agriculture/CIAT)
Image: CIAT

Global Ideas: What is important about beans, why are they referred to as the "meat of the poor?"

Steve Beebe: Beans are a staple food for more than 400 million people in the tropics and sub-tropics, in Latin America and Africa. Especially in East Africa, people can consume up 60 kilograms per capita per year. Rwanda is an especially big consumer, as well as western Kenya. Beans, like other legumes, have a high percentage of protein - between 20 and 25 percent - and given their relatively low price, they are often called "the meat of the poor."

Can you describe the difference between the new bean "lines" and common types of beans?

Beans come in all different colors, shapes and sizes, so a comparison of bean types needs to be made within a particular bean class - comparing apples with apples and oranges with oranges. The best heat tolerant materials that we have to date are in the small red bean class that is popular in Central America and parts of East Africa. The essential difference that is visible with the heat tolerant beans is exactly that - their heat tolerance. Several are also drought tolerant. Apart from that, a farmer will not see any difference.

Where did the heat resistent beans come from, did you have them in your database and how did you filter them out?

The heat tolerant beans emerged from some interspecific crosses that were made some years ago by a colleague who was combining the common bean with a distant cousin, the tepary bean (its scientific name is Phaseolus acutifolius). The #Link:http://edis.ifas.ufl.edu/mv025:tepary bean# evolved in the deserts of the US south-west and Mexico, so it is naturally heat tolerant and designed for climate change by mother nature. For our purposes however, it is not very appealing because it is very small and lacking the bright colors that we like, and farmers would not be attracted to it because it has a low growing plant type - with pods close to the ground in danger of infection by fungi. When we started to focus attention on heat tolerance, we went to our storeroom and pulled out what we could find, both our most recent elite lines and lines from the past. Among those lines were the interspecific materials, and although we had less than a hundred of them, that was where we found most of our heat tolerance.

How does breeding of beans work - do you know the qualities of certain bean types and then start to figure out how to strengthen them?

Breeders work with genetic diversity, and when they need a trait, if they can't find it close at hand in materials and lines in their own breeding program, they go further afield to look for it. One of our most important resources is the gene bank. In the case of common beans, the largest in the world is held in the International #Link:http://ciat.cgiar.org/:Center of Tropical Agriculture (CIAT)# by its Spanish acronym), one of the centers of the CGIAR system. Breeding starts with the process of evaluating these hundreds or thousands of bean types - most of them old farmer varieties from around the world - searching for the trait of interest. The common bean is lucky to have sister species and distant cousins with which it can be crossed, although with some difficulty. To cross with tepary bean, some "bean surgeon" needs to pluck out the tiny embryo from the pod, like a premature baby, to culture it in the laboratory, because it won't grow on its own. That's why most breeders don't work with crosses that are as wide as this.

For heat tolerance, the identification of tolerant lines is very easy - look for plants that produce pods, because the sensitive materials produce little or nothing at all. This is because the high temperatures interfere with the pollination process, and no pods and seeds are produced, so selection is largely visual. If it looks productive, select it.

If you have identified promising beans - can you describe how they are tested to assure that the bean will work in a hotter environment?

This phase of the work is essentially empirical: try it and see. Lines that are promising for a given trait will be tested for yield, disease resistance or - in this case - heat tolerance, which is essentially the same as yield in these hot environments. Many other factors will determine if a material merits becoming a variety, for example, its time to harvest (farmers often like early maturing varieties) or drought tolerance.

There is a legal process that accompanies this testing procedure. Yield tests must be inspected and certified for a certain number of years (the number depends on the requirements of each country) and if a material passes the test and is demonstrated to have advantages over existing varieties, then it is formally registered to be distributed as a new variety.

You do have about 750,000 samples of important food crops in your database - do you expect similar developments just like the beans in the future?

Biology is remarkably diverse and resilient, and it has evolved over millenia in many environments including some very extreme ones. The seeds that are stored in gene banks carry history in their DNA that we still are unpacking. It is to be expected that many of the solutions for tomorrow's problems can be found there, but those happy outcomes can only occur if sufficient funding is available. It will be an arduous and long-term task to dig the gems out of the gene banks and turn them into varieties of the future.

Can you give an insight into food security in the future - if temperatures are rising, what has to happen to ensure a reliable food supply for the world?

I certainly cannot predict what will happen to food security, and I doubt that anyone else can either. Climate change is much more than higher temperatures. In some places it means drought, in other regions it means excess rain and flooding. New diseases may emerge or old ones may be redistributed as the environment changes. Nonetheless, I am optimistic that we are capable of meeting the challenges of the future, if we approach those challenges with a multi-disciplinary approach. Plant breeding is an important component, and so is soil science. Farmers have great capacity to adapt, and that capacity needs to be enhanced. Finally, government policy will be key to set in motion the steps to prepare for extreme events, investing in research, and also setting up the social structures to protect farmers and society from the effects of climate change.

Thank you very much for the interview.