Genebanks are the future . . . but there is a big challenge ahead

Our ability to adapt to changing climates will be determined, to a considerable extent, upon our ability to feed ourselves, to provide shelter and clothing, and for many peoples in many developing countries there will be problems in obtaining fuelwood for cooking or heating.

My close friend and former colleague Professor Brian Ford-Lloyd and I wrote that 30 years ago in the first chapter [1] of the book on climate change and genetic resources that we edited with Martin Parry.

We also wrote that to avert famine it would be necessary to raise crop yields and identify and use the sorts of genetic resources to contribute to this effort. Fortunately, these genetic resources are, to a large extent, already conserved in genebanks around the world.

In a recent post, I argued that, in the face of climate change, genebanks are the future. And while I hold to that assertion, I must also highlight a challenge that must be addressed—with greater urgency—and one that I already raised 30 years ago!

And that challenge is all about the potential impacts of climate change on genebank operations. I’m concerned about how rising temperatures and changing seasons might affect the ability of a genebank to produce good quality seeds during initial multiplication or thereafter to regenerate seed stocks.

We also have limited information how the environmental pest and plant pathogen load will change under a changing climate. That’s a particular concern for plant species that cannot be stored as seeds but are conserved in field genebanks. In this, the International Year of Plant Health, it is a particular genebank issue worthy of more attention.

Furthermore, we shouldn’t discount possible increases in genebank costs as cooling equipment works harder to maintain cold rooms at the desired temperatures of -18°C for long-term conservation (in so-called Base Collections), or just above 0°C for germplasm that is available for distribution and exchange (in Active Collections), the situation found in many genebanks.

Many (but not all) genebanks were set up in parts of the world where the crops they conserve are important, and where many originated, in so-called ‘centers of diversity’. That holds particularly for the international genebanks managed in eleven of the CGIAR centers, such as for potatoes at the International Potato Center (CIP) in Peru, beans and cassava at the International Center for Tropical Agriculture (CIAT) in Colombia, or rice at the International Rice Research Institute (IRRI) in the Philippines, to give just three examples.

But there are exceptions. CIMMYT, the International Maize and Wheat Improvement Center (located just outside Mexico City) certainly lies in the center of diversity for maize, but not wheat, which is a crop that was domesticated and evolved under domestication in the Near East and fringes of the Mediterranean. Another exception is Bioversity International, based in Rome that maintains an important collection of bananas (Musa spp.) as tissue culture samples (known as in vitro conservation) as well as samples stored frozen (or cryopreserved) at the temperature of liquid nitrogen (-196°C) in Belgium at the Katholieke Universiteit Leuven (KU Leuven).

You can find out more about the CGIAR genebanks on the Genebank Platform website.

As the network of genebanks expanded worldwide, with almost every country setting up at least one national genebank, many genebanks now hold samples of varieties and wild species from distance regions. And it does have some important implications for long-term conservation and regeneration, and exchange of germplasm.

Long-term conservation of many plant species in genebanks is possible because their seeds can be dried to a low moisture content and stored at low temperature. We refer to these seeds as orthodox, and we have a pretty good idea of how to dry them to an optimum moisture content (although research at IRRI has thrown new light on some of the critical drying processes). Provided they can be kept dry and cool, we can predict—with some confidence—how long they will survive in storage before they need to be grown again, or ‘regenerated’, to produce healthy seeds stocks.

On the other hand, the seeds of some species, many from the tropics, do not tolerate desiccation or low temperature storage. We refer to the seeds of these species as recalcitrant. There again, there is also a group of crops that cannot be stored as seeds but must be maintained, like the banana example referred to above, as tissue cultures or cryopreserved, if technically feasible; or in field genebanks because they reproduce vegetatively. The potato for example is grown from tubers, and for any variety, each tuber is genetically identical (a clone) to all the others of that variety. Although potatoes do produce seeds (often in abundance), they do not breed true. That’s why conservation of the original varieties is so important.

However, seeds do not live forever, and periodically regenerated if there are signs of declining viability. Or when seed stocks have become depleted because they have been sent to breeders and researchers around the world.

Climate change is already affecting crop productivity in some parts of the world. Increases in temperature (notably higher nighttime temperatures) are linked with a reduction of fertility in rice [2] for example. Stressed plants produce seeds of lower quality and, in wheat, have an effect on seedling vigour and potentially on yield [3].

Many (perhaps most) genebanks aim to grow their germplasm close to the genebank location, although this may not always be possible. Will the environments of genebank locations remain constant under climate change? Most certainly not. Temperatures have already risen, and are predicted to increase even further unless governments really do take concerted action to reduce our carbon footprint. While temperatures will increase, daylength will remain constant. Under climate change we will see new combinations of temperature and daylength. Response to daylength (or photoperiodism) is a key adaptive trait in many plant species. It is already a challenge to grow some genebank samples at a single location because of their wide latitudinal provenance.

Richard Ellis

Incidentally, 30 years on, it’s worthwhile to take a second look at Chapter 6 in our genetic resources and climate change book [4] by Professor Richard Ellis and colleagues at the University of Reading on the relationship between temperature and crop development and growth.

Seed quality is all important for genebank managers. Unlike farmers, however, they are less concerned about yield per se. They do need to understand the impacts of higher temperatures, drought, or submergence—and when they occur in a plant’s life cycle—on seed quality, because seed quality is a key determinant of long-term survival of seeds.

In a recent article, Richard wrote this: . . . when scientists breed new crop varieties using genebank samples as “parents”, they should include the ability to produce high-quality seed in stressful environments in the variety’s selected traits. In this way, we should be able to produce new varieties of seeds that can withstand the increasingly extreme pressures of climate change.

While a genebank might be able to regenerate its conserved germplasm closeby today, to what extent will these ‘regeneration environments’ become ‘stressful environments’ under a changing climate? What measures must a genebank take to ensure the production of the highest quality seeds? Furthermore, how will the pest and disease load change, and what impact will that have during regeneration and, perhaps more importantly, on germplasm conserved in field genebanks?

We were faced by a similar situation almost 30 years ago after I had joined IRRI. There’s no question that IRRI conserves, in its International Rice Genebank, the world’s largest and genetically most diverse collection of rice varieties and wild species.

Kameswara Rao

One important group of rice varieties, the so-called japonica rices originated in temperate zones, and it was tricky to produce high quality seeds in Los Baños (14°N). With my colleague Kameswara Rao (who received his PhD in Richard’s lab at Reading), we carefully analysed the factors affecting seed quality in the japonica varieties grown in Los Baños [5], and adapted the regeneration cycle to the most appropriate time of year. Given that water was not a limiting factor (there were irrigation ponds on the IRRI Experiment Station) we were not constrained by the changing seasons as such. This would not be possible for all genebanks where growing seasons are more differentiated, in terms of temperature and water availability.

I did look into the possibility of growing the japonica (and other ‘difficult’ varieties) at other sites, even outside the Philippines. What seemed, at the outset, as a logical solution to a challenging problem, became a logistical nightmare.

I was concerned that the International Rice Genebank could ‘lose’ control of the management of germplasm samples in the field unless genebank staff were assigned to oversee that work, even in another country. Afterall, the reputation of the genebank lies in its ability to safely conserve germplasm over the long-term and safely distribute seeds, conditions I was not prepared to compromise.

There were also various plant quarantine issues, seemingly insurmountable. Plant quarantine personnel are, by outlook, a conservative bunch of people. And with good reason. IRRI successfully operates its germplasm exchange (both receipt and distribution) under the auspices of the Philippines Department of Agriculture’s National Plant Quarantine Services Division (of the Bureau of Plant Industry). The institute’s Seed Health Unit carries out all the tests necessary to certify all imports and exports of rice seeds meet exacting quarantine standards. All samples received by IRRI must be tested and, if they are destined for future distribution, must be grown in the field at IRRI for further observation and certification. That would negate the advantages of producing seeds in a ‘better’ environment. Countries like the USA or Russia that cover a huge range of latitude and longitude have a network of experiment stations where germplasm could be grown, and under the same plant quarantine jurisdiction. For many countries and their genebanks, that will just not be an option.

So the challenge for genebank managers is to make sure the impact of climate change on germplasm management and exchange is part of risk management. And begin discussions (if they have not already started) to determine how inter-genebank collaboration could overcome some of the potential constraints I have raised.

[1] Jackson, M.T. & B.V. Ford-Lloyd, 1990. Plant genetic resources – a perspective. In: M. Jackson, B.V. Ford-Lloyd & M.L. Parry (eds.), Climatic Change and Plant Genetic Resources. Belhaven Press, London, pp. 1-17. PDF

[2] Shaobing Peng et al., 2004) Rice yields decline with higher night temperature from global warming.

[3] Khah, EM et al., 1989. Effects of seed ageing on growth and yield of spring wheat at different plant-population densities. Field Crops Research 20: 175-190.

[4] Ellis, RH et al., 1990. Quantitative relations between temperature and crop development and growth. In: M. Jackson, B.V. Ford-Lloyd & M.L. Parry (eds.), Climatic Change and Plant Genetic Resources. Belhaven Press, London, pp. 85-115.

[5] Kameswara Rao, N. & Jackson, MT, 1996. Seed production environment and storage longevity of japonica rices (Oryza sativa L.). Seed Science Research 6, 17-21. PDF