GHU: Gateway for the safe exchange of germplasm

Lava Kumar,

Seed testing. Photo by L. Kumar, IITA.
Seed testing. Photo by L. Kumar, IITA.

International exchange of germplasm: an essential step for sharing international public goods
Since its inception in 1967, IITA has been actively involved in the collection, conservation, and use of the plant genetic resources of important crops, such as banana and plantain, cassava, cowpea, maize, soybean, and yam, and their wild relatives from Africa and other parts of the world. Using this germplasm, IITA’s crop improvement programs, based in several locations in sub-Saharan Africa, have been developing high-yielding, nutritionally superior crop varieties resistant to pests, diseases, and drought.

These are regularly exchanged with national and international programs for crop improvement and agriculture development.

Germplasm safety matters
As part of the measures to prevent the inadvertent spread of pests through exchange activities, IITA has established a Germplasm Health Unit (GHU). The GHU is responsible for the production, maintenance, and exchange of healthy (pest-free) germplasm in accordance with the international requirements on plant protection. These are covered by the International Plant Protection Convention (IPPC) under the auspices of FAO, and those set up by the Inter-African Phytosanitary Council (IAPSC) and National Plant Protection Organizations (NPPOs) to safeguard agriculture and natural resources from the risks associated with the entry, establishment, or spread of plant pests.

Scheme for phytosanitary management of germplasm.
Scheme for phytosanitary management of germplasm.

GHU (a) facilitates germplasm exchange in support of IITA’s international crop improvement programs; (b) inspects for pests and certifies the health status of germplasm; (c) ensures compliance with the national regulations on plant introductions and exports; (d) guards against the introduction of exotic pests into countries where they do not occur; (e) ensures phytosanitary management of plant genetic resources conserved in the IITA genebank; and (f) provides capacity building and awareness creation on phytosanitary measures.

GHU operates within the framework of the procedures for the introduction and export of germplasm established by the government of the host country in which IITA’s operations are based. For instance, all the exchange operations of IITA’s activities in Nigeria are organized in accordance with the legislation of the Nigerian Agriculture Quarantine Service (NAQS) of the Federal Department of Agriculture, Nigeria.


Ensuring exchange of clean germplasm
Crops researched at IITA comprise those propagated through botanical seeds or true seeds (maize, soybean, cowpea, and other legumes of importance to African farming) and crops that are propagated through vegetative propagules, including stems (e.g., cassava), tubers (e.g., yam), and in vitro plants (e.g., banana and plantain, cassava, and yam).

Each type of germplasm demands a unique set of procedures for assessing the health status of the material. At IITA, this work goes on from production to postharvest to the point when the material is dispatched.

Plant material generated for international exchange is inspected with the technical officers of NPPO during the active growth stage in the field or screenhouse to ensure the selection of pest-free material. The sorted materials (seeds or vegetative propagules) are then brought to the GHU laboratories for critical inspection for the presence of pests. Detection methods used for this purpose include visual inspection of dry seeds, seed washing, agar and blotter tests, seed soaking, and seedling symptom tests which aid in identifying any pest-infested material. Additional techniques are used for pest identification including culturing techniques, microscopy, and biochemical analyses of samples by enzyme-linked immunosorbent assay (ELISA), polymerase chain reaction (PCR), and genomic sequencing. Only materials that are free of the regulated and unregulated quarantine pests are released for international exchange.

GHU also monitors for genetically modified organisms (GMO) to comply with the Cartagena biosafety protocol, also under the regulation of NPPOs. This is done mainly by seeking an additional declaration from the exporting parties on the GMO status of the planting material as stipulated in the conditions of the import permit issued by the NPPO. Diagnostic capacity exists to monitor germplasm for traces of GMOs by PCR assays, targeting constitutive elements of transgene constructs, such as promoters of Agrobacterium tumefaciens or Cauliflower mosaic virus 35S gene, that are widely used for generating transgenic plants.


Complying with regulations
Germplasm exchange activity commences with the application of a permit from a host country for germplasm import (for use in IITA’s R4D programs) or germplasm export (to partners, collaborators and other stakeholders, including IITA’s missions in other countries). This is an essential process under the Convention of Biological Diversity (CBD) treaty that regards biodiversity as a national treasure, and requires authorization from the respective governments for free exchanges. Every country has a nodal agency tasked with issuing permits for the movement of germplasm.

In addition, GHU applies for phytosanitary certificates (PC) for the export of material. The PC is issued by NPPO after the condition has been satisfied that the material being exported meets the phytosanitary standards of the IPPC and the importing country. GHU invariably complies with national regulations in obtaining these two documents for all seeds or plant materials sent or received. Similarly, when material is imported it is subjected to post-entry inspection to ensure its compliance with the conditions specified in the import permit. Depending on the need, material is held in the post-entry isolation facility until the necessary clearances are obtained. Material that satisfies all the conditions is released for IITA’s use.

Germplasm export and import events facilitated by GHU to various countries around the world. Source: L. Kumar, IITA.
Germplasm export and import events facilitated by GHU to various countries around the world. Source: L. Kumar, IITA.

From 2005 to 2010, GHU, from IITA‘s Ibadan Station in Nigeria in liaison with NAQS, has facilitated about 492 exchanges, 157 imports, and 335 exports of crop and other plant material to 69 countries, 34 of which are in Africa (Fig. 1). USA, India, Colombia, Mexico, and Japan are among the top 5 non-African countries. Within Africa, the top 5 countries with which IITA has exchanged germplasm are Bénin, Ghana, Cameroon, Kenya, and South Africa. Each of these countries has specific legislation. However, procedures for health monitoring have the same underlying principle, i.e., the exclusion of pests and the prevention of pests from spreading.


Phytosanitary protection of genetic resources
GHU ensures the phytosanitary management of the germplasm of food crops (about 27,000 accessions) conserved in the IITA genebank and also in the in situ germplasm collections of breeding programs. Germplasm conserved in the genebank is systematically evaluated for its health status and clean germplasm is conserved for distribution by IITA’s Genetic Resources Center (GRC).

Contributing to phytosanitary capacity development in SSA
Together with the Virology and Molecular Diagnostic Unit and GRC at IITA, Ibadan, GHU augments diagnostic procedures for monitoring pests in germplasm; develops a reference pest collection and DNA bank to use as controls; establishes DNA barcode databases of the pests of African food crops; and augments procedures for salvaging clean germplasm.

Information dissemination through exhibits and hands-on demos, IITA Open Day. Photo by IITA.
Information dissemination through exhibits and hands-on demos, IITA Open Day. Photo by IITA.

GHU plays an active role in developing the skills of NPPOs in the testing for germplasm health and the production of pest-free germplasm via training courses and short-term assignments. It also creates awareness on quarantine pests, quality standards for planting material, and the sanitary and phytosanitary (SPS) measures.

Knowledge and technologies developed are disseminated through training programs, the publication of protocol manuals, information flyers and a website. The unit also collaborates with NPPOs and IAPSC as a technical partner to develop phytosanitary capacity in Africa.


Why conserve germfree-germplasm?

Dominique Dumet, and Lava Kumar,

Seeds of important grain legumes are conserved in IITA's Genetic Resources Center. Photo by IITA.
Seeds of important grain legumes are conserved in IITA's Genetic Resources Center. Photo by IITA.

Plant genetic resources (germplasm) are the foundation for sustainable agriculture and global food security. They possess genes that offer resistance to pests and diseases and resilience to abiotic stresses, such as drought tolerance, soil erosion, and other constraints.

However, genetic resources are eroding at unprecedented rates as a result of the loss of habitat, outbreaks of pests and diseases, and abiotic stresses. Therefore, it has become imperative to conserve genetic resources for agricultural sustainability and the preservation of global biodiversity.

In the mid-1970s, IITA has initiated an ex situ conservation of germplasm of important African food crops which are held in trust on behalf of humanity under the auspices of the United Nations. To date, IITA’s Genetic Resources Center (GRC) conserves over 27,000 accessions of six main collections of African staple crops, namely, cowpea and other Vigna, soybean, maize, cassava, banana, and yam. Germplasm is distributed worldwide for use in research for food and agriculture. Depending on the species’ reproductive biology and mode of dissemination, collections are stored in field, seed, or in vitro genebanks.

Conservation of virus-free germplasm. Source: L. Kumar, IITA.
Conservation of virus-free germplasm. Source: L. Kumar, IITA.

However, germplasm (seeds or vegetative propagules) infested with pathogens such as, viruses, fungi, bacteria, and nematodes, insects, mites and even weeds (hereafter all referred to as pests) can spread along with the planting materials. Because of this risk, planting materials are traditionally sourced from healthy-looking plants and as an additional safety measure they are treated with chemicals to eliminate bacteria, fungi, nematodes, insects and other pests. However, viral pathogens are difficult to detect and pose challenges to “clean” (pest-free) planting material production procedures. IITA’s collections were sourced over 35 years from several countries in Africa and other parts of the world.

Knowledge on viruses infecting crops conserved in the IITA genebank and the means for their detection and production of clean planting material have dramatically improved over the past two decades. To ensure that germplasm conserved is free of pests, particularly viruses, a systematic approach was taken to assess the health status of every accession in the genebank and produce clean planting materials for conservation.

For seed-propagated crops (maize and legumes), clean seed production requires planting accessions in contained screenhouses. Emerging plants are monitored for symptoms and each plant is tested using diagnostic tools for all known seed-transmitted viruses occurring in the territory where they were last grown. Plants that test positive for virus and/or showing virus-like symptoms are destroyed. Seeds are harvested from the virus-negative, healthy-looking plants. Clean seeds are then deposited in the germplasm collections. This work started in 2008, and so far over 4000 accessions of legumes have been evaluated and clean seed material produced have been conserved in the genebank.

Researcher in genebank. Photo by IITA.
Researcher in genebank. Photo by IITA.

For clonally propagated crops (cassava, yam and banana), production of clean planting material involves in vitro procedures using meristem culture. In cassava, source plants are subjected to thermotherapy (exposing plants to 27-30 °C) from 1 to 3 weeks prior to meristem excision and in vitro propagation. In vitro plants are indexed for viruses and plants that test positive are discarded while virus-negative plants are further propagated for conservation in the in vitro genebank. So far, over 2000 accessions of clonal crops have been subjected to this process to derive virus-free plants.

Production and conservation of “clean” planting material is expensive; however it improves the turn-around time for processing germplasm for exchange and dramatically improves its use. In addition, clean germplasm improves the viability of the material conserved in the genebank and prevents the risk of the accidental spread of pests from one region to another through the planting materials.

African yam bean: a food security crop?

Daniel Adewale,

Read the Ukranian translation by Martha Ruszkowski

Diversity in color, color pattern, structure, texture, brilliance, etc. of African yam bean seeds. Photo by D. Adewale, IITA.
Diversity in color, color pattern, structure, texture, brilliance, etc. of African yam bean seeds. Photo by D. Adewale, IITA.

Biodiversity assures the evolutionary continuity of species. The collection and conservation of diversity within species are a safeguard against the loss of germplasm. They provide a buffer against environmental threats and assure continual and sustainable productivity. Global food security is becoming shaky with increasing dependence on a few major staple crops. This has resulted in an alarming reduction not only in crop diversity but also in the variability within crops.

The conservation and maintenance of agrobiodiversity of neglected and underutilized plant species such as African yam bean (AYB) in seed banks aim at contributing to food security and preventing a potential food crisis. Increasing the use of underutilized crops is one of the better ways to reduce nutritional, environmental, and financial vulnerability in times of change (Jaenicke and Pasiecznik 2009); their contribution to food security is unquestionably significant (Naylor et al. 2004, Oniang’o et al. 2006). Among other things, the consumption of a broader range of plant species ensures good health and nutrition, income generation, and ecological sustainability.

Potentials of African yam bean
The plant (Sphenostylis stenocarpa) is one of the most important tuberous legumes of tropical Africa. It is usually cultivated as a secondary crop with yam in Ghana and Nigeria. A few farmers who still hold some seed stocks, especially the white with black-eye pattern, plant it at the base of yam mounds in June or July. The crop flourishes and takes over the stakes from senescing yam. It flowers and begins to set fruits from late September and October. The large bright purple flowers result in long linear pods that could house about 20 seeds.

The seed grains and the tubers are the two major organs of immense economic importance as food for Africans. This indigenous crop has huge potential for food security in Africa. However, there are cultural and regional preferences. In West Africa, the seeds are preferred to the tubers but the tubers are relished in East and Central Africa (Potter 1992). The crop replaces cowpea in some parts of southwestern Nigeria (Okpara and Omaliko (1995). Researchers (Uguru and Madukaife 2001) who did a nutritional evaluation of 44 genotypes of AYB reported that the crop is well balanced in essential amino acids and has a higher amino acid content than pigeon pea, cowpea, and bambara groundnut.

Tuber yield per stand of AYB accession TSs96 at Ibadan, 2006. Photo by D. Adewale, IITA.
Tuber yield per stand of AYB accession TSs96 at Ibadan, 2006. Photo by D. Adewale, IITA.

Apart from the use of soybean as an alternative to animal protein, protein from other plant sources is not often exploited. The protein content in AYB grains ranged between 21 and 29% and in the tubers it is about 2 to 3 times the amount in potatoes (Uguru and Madukaife 2001, Okigbo 1973). AYB produces an appreciable yield under diverse environmental conditions (Anochili 1984, Schippers 2000). Another positive contribution of the crop to food security is the identification of the presence of lectin in the seeds, which could be a potent biological control for most leguminous pests.

Although the vast genetic and economic potentials of AYB have been recognized, especially in reducing malnutrition among Africans, the crop has not received adequate research attention. Up to now, it is classified as a neglected underutilized species or NUS (Bioversity 2009). Devos et al. (1980) stressed that the danger of losing essential germplasm hangs over all cultivated food crop species in tropical Africa, especially those not receiving research attention. The quantity and availability of AYB germplasm is decreasing with time. At one time, Klu et al. (2001) had speculated that the crop was nearing extinction; its inherent ability to adapt to diverse environments (Anochili 1984, Schippers 2000) may have been responsible for its continual existence and survival. Nevertheless, scientists think that the genetic resources of AYB may have been undergoing gradual erosion.

IITA keeps some accessions of the crop, but otherwise, its conservation in Nigeria is very poor and access to its genetic resources is severely limited. Seeds of AYB seem to be available in the hands of those who appreciate its value, i.e., the elderly farmers and women in a few rural areas in Nigeria. The ancient landraces in the hands of local farmers are the only form of AYB germplasm; no formal hybrid had been produced as yet.

Improvement of the crop is possible only when the intraspecific variability of the large genetic resources of the species is ascertained. The genetic resources of AYB need to be saved for use in genetic improvement through further exploration in tropical Africa and for conservation.

African yam bean plant showing mature pods ready for harvest. Photo by Daniel Adewale, IITA.
African yam bean plant showing mature pods ready for harvest. Photo by Daniel Adewale, IITA.

Understanding AYB
Eighty accessions (half of the total AYB collection under conservation in the IITA genebank) were assessed for diversity using morphological and molecular methods. Thirty selected accessions were further tested in four ecogeographical zones in Nigeria to understand their productivity and stability. The breeding mode was also studied.

Findings show that each of the 80 accessions of AYB has a unique and unmistakable genetic entity, promising to be an invaluable genotype as a parent for crop improvement. Morphologically, two groups have evolved: the tuber forming and the nontuber forming.

Grain yield differed among individual accessions and across the four agroecologies. The average grain yield across the four diverse environments in Nigeria (Ibadan, Ikenne, Mokwa, and Ubiaja) was ~1.1 t/ha; however, grain yield at Ubiaja was well above 2 t. Most agronomic and yield-determining traits had high broad sense heritability and genetic advances, assuring high and reliable genetic improvement in the species. AYB is both self fertilizing and an outcrosser; the latter trait is exhibited at about 10%.

The good news is improvement through hybridization is possible within the species.

Anochili, B.C. 1984. Tropical Agricultural Handbook. Pages 48–50 in Food Crop Production. Macmillan Publishers, London, UK.

Bioversity International. 2009. [25 February 2010].

Devos, P., G.F. Wilson, and E. Delanghe. 1980. Plantain: Genetic resources and potential in Africa. Pages 150–157 in Genetic Resource of Legumes in Africa edited by Doku, E.V. Proceedings of a workshop jointly organized by the Association for the Advancement of Agricultural Science in Africa and IITA, Ibadan, Nigeria, 4–6 January 1978.

Jaenicke, H. and N. Pasiecznik. 2009. Making most of underutilized crops. LEISA Magazine, 25(1):11–12.

Klu, G.Y.P., H.M. Amoatey, D. Bansa, and F.K. Kumaga. 2001. Cultivation and uses of African yam bean (Sphenostylis stenocarpa) in the Volta Region of Ghana. The Journal of Food Technology in Africa 6:74–77.

Naylor, R.L., W.P. Falcon, R.M. Goodman, M.M. Jahn, T. Sengooba, H. Tefera, and R.J. Nelson. 2004. Biotechnology in the developing world: a case for increased investment in orphan crops. Food Policy 29:15–44.

Okigbo, B.N. 1973. Introducing the yam bean (Sphenostylis stenocarpa) (Hochst ex. A. Rich.) Harms. Proceedings of the first IITA Grain Legume Improvement Workshop, 29 October–2 November 1973, Ibadan. Nigeria. pp. 224–238.

Okpara, D.A. and C.P.E. Omaliko. 1995. Effects of staking, nitrogen and phosphorus fertilizer rates on yield and yield components of African yam bean (Sphenostylis stenocarpa). Ghana Journal of Agricultural Science 28:23–28.

Oniang’o, R.K., K. Shiundu, P. Maundu, and T. Johns. 2006. Diversity, nutrition and food security: the case of African leafy vegetables in Hunger and poverty: the role of biodiversity. Report of an International Consultation on the role of biodiversity in achieving the UN Millennium Development Goal of freedom from hunger and poverty edited by Ravi, S.B., I. Hoeschle-Zeledon, M.S. Swaminathan, and E. Frison. Chennai, India, 18–19 April 2005. M.S. Swaminathan Research Foundation, Chennai, India. pp. 83–100.

Potter, D. 1992. Economic botany of Sphenostylis (Leguminosae). Economic Botany, 46: 262-275.

Schippers, R.R. 2000. African indigenous vegetables: An overview of the cultivated species. Natural Resources Institute/ ACP-EU Technical Centre for Agricultural and Rural Cooperation, Chatham, UK. pp. 89–98.

Uguru, M.I. and S.O. Madukaife. 2001. Studies on the variability in agronomic and nutritive characteristics of African yam bean (Sphenostylis stenocarpa Hochst ex. A. Rich. Harms). Plant Production and Research Journal 6:10-19.

Dominique Dumet: Safeguarding agrobiodiversity for the future

Dominique Dumet showing seeds, IITA genebank. Photo by J. Oliver.
Dominique Dumet showing seeds, IITA genebank. Photo by J. Oliver.

As the head of IITA’s Genetic Resources Center (GRC), Dominique Dumet says she is something between a curator and an administrator. She is involved in conservation (field bank, seed bank, and in vitro bank, which includes cryopreservation for clonal crops), checking inventory, improving processes and workflows, transferring technology, and computerizing the system. In addition, she is involved in recruiting staff and selecting students, germplasm distribution and acquisition, research in plant genetic resources, staff management, research project development and proposal writing, and communication to donors on special projects and about germplasm at IITA during scientific meetings.

She is primarily interested in ex situ conservation and particularly low temperature biology and its application to conservation systems (cryopreservation, sanitation). She has an overview of all domains of germplasm conservation and takes part in various research projects as a collaborator to “add value to the germplasm.” She no longer considers herself a researcher, since she spends most of her time administering the genebank and planning or writing proposal or reports. This International Year of Biodiversity, she explains what GRC plans in support of promoting biodiversity conservation.

Why is biodiversity conservation important? What are your priorities?
Our work is very important. We try to reduce the rate of irreversible loss in the biological diversity that is used in agriculture. All conservation aspects are important, but maybe the conservation sensu stricto comes first if we have to choose as we have a responsibility towards the international community and if we do not work well, all may suffer from our mistakes.

What do you like about working in Africa? In your field of specialization?
I am proud of my job. I hope I contribute to improving the well being of the poorest even if for one iota. I also like being in an environment very different to the one in which I grew up.

In vitro biology and cryopreservation in particular is my field of specialization. Cryopreservation fascinates me as I find it amazing that we can stop the life of a tissue and bring it back again whenever we want to do so. In the frozen stage, all biochemical or biological processes stop—that means that everything stops moving at one moment—and then the magic of life makes it start again so long as physical and chemical parameters are adequate (cooling and thawing temperature, osmotic pressure, light, growth regulators, etc.).

What are your challenges and constraints at work?
The challenges are to maintain the bank at international standards and to keep all the accessions alive. Some constraints include unforeseen requests which make us work under pressure as we still have our routine activities, and new concepts that make our system obsolete.

Collection recording with barcode inventory system, IITA genebank. Photo by O. Adebayo, IITA.
Collection recording with barcode inventory system, IITA genebank. Photo by O. Adebayo, IITA.

How do you make the many visitors to GRC understand and appreciate what you are doing?
I give information on the basic concepts of diversity, I explain why we need to conserve it ex situ (out of the natural environment) because of the genetic erosion taking place in the field. Then I explain how we maintain it via seeds or field and in vitro banks, depending on the crop. I also show some examples of diversity, e.g., cowpea seed collection and the variation observed at seed coat. I provide some background on the gaps in the collection based on GIS. And I generally conclude with the International Treaty and access to plant genetic resources for food and agriculture (PGRFA).

Please cite some concrete steps being taken by IITA in biodiversity conservation.
IITA was involved in collecting genetic resources as early as the 1970s so we do have a long history in investing in biodiversity conservation. Many collecting missions have been organized and germplasm has been also acquired from many national collections. The majority of the collections have now been described at agromorphological level, but we are still working on it for maize, for example. We have to characterize any new accessions coming into the bank.

Recently we organized a meeting and survey to develop the cowpea global conservation strategy (Trust-funded). We will have the same strategy developed for yam in 2010 (we are also organizing the Trust-funded expert meeting for this). We are developing more efficient conservation processes such as cryopreservation (this lowers costs but also limits genetic variation during storage). We are fingerprinting the collections of clonal crops to identify germplasm at accession level. This will further guide our collecting missions.

Do you think governments everywhere are serious about biodiversity conservation?
That depends on the country. The richer ones certainly take more serious action—but the poorest (or the less organized) do not have this ‘luxury’. I think all understand the value of biodiversity but as it is a long-term investment to store and as the return on investment is not guaranteed, countries either ignore it or do little about it.

What is the state of agrobiodiversity in Africa?
It is not too bad, compared to other continents—my view on this is that Africa has not yet undergone its Green Revolution (but this opinion may be controversial). However, things may change very quickly, especially now that Africa is seen as a big field where agriculture can take off. Somehow, if we are successful in producing high-yielding crops the adoption rate of such high potential crops may quickly wipe away natural diversity, including (but not only) the landraces (varieties developed by farmers over thousands of years). When the elite genotype replaces older varieties it makes the low performing one obsolete and it increases the rate of planting (as it can generate higher revenue). We have to be vigilant about this since we, as breeders of improved varieties, are partly responsible. There is a conflict of interest between agriculture intensification and conservation of biodiversity.

Do farmers understand the need to conserve seeds or genetic resources for future generations?
In general I would think they are the first one to know about biodiversity but they may not be aware of the amplitude of the “erosion” of species.

Some are already organized in community based genebanks and there are participatory conservation projects within the CGIAR but I do not know enough about the topic. This may be an important complementary approach, but participatory conservation may be difficult to sustain. Besides in community based conservation, the incentive is cultural preference. That means only materials of immediate interest for the farmers are kept.

Bambara groundnut seeds. Photo by J. Oliver, IITA.
Bambara groundnut seeds. Photo by J. Oliver, IITA.

What is the status of IITA’s seed shipment to Svalbard in Norway?
We had planned on sending more than 20,000 accessions of cowpea and its relatives, bambara groundnut, maize, and soybean in the next few years. Cowpea makes up the majority of the accessions that we are sending. There is a bit of deviation from the original plan but we are more or less on track.

Being the lead person in agrobiodiversity conservation in the Institute, how do you plan to mark the UN International Year of Biodiversity?
We plan to raise awareness about biodiversity among the youth, i.e., high school students and adults in the local community. We will organize quiz contests, tree planting activities, excursions to the IITA forest and to the genebank; produce information materials (videos, flyers, handouts) and set up roaming exhibits and posters.

We also plan to organize seminars and a field or biodiversity/community day for students, farmers, and residents in the local community. We will be coordinating with partners from the University of Ibadan, local schools, Alliance Française, and other organizations, such as the National Center for Genetic Resources and Biotechnology, Nigeria Institute of Horticulture, and University of Abeokuta.

What would be your message to colleagues about biodiversity conservation?
Don’t just conserve; educate as well.

Biodiversity conservation is key

Dominique Dumet,

Researcher sorting bambara groundnut seeds, IITA genebank. Photo by J. Oliver.
Researcher sorting bambara groundnut seeds, IITA genebank. Photo by J. Oliver.

Biodiversity or biological diversity is the variety of life on earth; it includes all living forms, animal, plant, or microbial. It is accessible at three levels: ecosystems, species within the ecosystem, and genes within the species. Today, 65 million years after the fifth and largest notable extinction of species (that wiped away the dinosaurs), alarming reports state an unprecedented rate of biodiversity loss—maybe the sixth extinction (Eldregde 1999).

The loss of spectacular trees in the rainforests or of polar bears at the North Pole is well-publicized and of great concern. However, equally worrying but so much less acknowledged is the loss of agricultural biodiversity. Agrobiodiversity refers to the part of biodiversity that feeds and nurtures people—whether derived from the genetic resources of plants, animals, fish, or forests. The diversity of these genetic resources is the foundation for sustainable agriculture and global food security. It enables plants to adapt to new pests and diseases as well as to climatic and environmental changes.

There are two complementary methods to conserve plant genetic resources: ex situ (in an artificial environment) and in situ (in a natural environment). Both approaches have pros and cons. In situ conservation allows further evolution of germplasm in natural conditions, but ex situ conservation allows ready access to clean germplasm.

Since its establishment in 1967, IITA has devoted considerable resources to ex situ conservation. In 1975, the Genetic Resources Unit was created to collect, conserve, and study food legumes, roots and tubers, and their wild relatives. Today, IITA’s Genetic Resources Center (GRC) maintains over 28,000 accessions of six main staple crop collections: black-eyed pea (cowpea), maize, soybean, cassava, yam, and banana. The biggest collection is of cowpea, with over 15,000 accessions collected or acquired in or from 89 countries, mainly in Africa. This biodiversity is very valuable for further genetic improvement and food security. It is maintained in trust for the international community and is available to all.

Any new sample entering the genebank is given a “passport” and a unique accession number. The passport holds important information related to the background of the accession. Such data, and in particular the georeference, i.e., the exact location where the sample was collected, provide valuable information. Indeed, when searching for drought tolerance traits, breeders may want to give priority to samples collected in dry areas. The analysis of georeferences of accessions also shows any potential ecogeographical gaps in the collection. Finally, the genetic erosion of a crop can be assessed during recollecting missions based on vernacular names and georeferences of already collected accessions. Unfortunately, for most collections, passport data are far from complete; the country of origin may be known, but the georeferences are missing. This lack of information is partly because the importance of passport data was underestimated in the past.

Diversity of crop genetic resources in the IITA genebank. Photo by IITA.
Diversity of crop genetic resources in the IITA genebank. Photo by IITA.

A collection of biodiversity is traditionally measured at the accession level using phenotypic characterization and evaluation descriptors. The former category generally refers to highly heritable, easily seen, measured, and expressed descriptors. The second includes descriptors that are more sensitive to the environment, such as yield or pest and disease resistance. Among the 52 international descriptors used to describe cowpea diversity, some quantitative traits show a high rate of diversity. Cowpea pod length varies from as little as 5.6 cm up to 49.9 cm, depending on the accession.

Vegetative trait diversity can be equally spectacular. Depending on the accession, the number of days required to harvest the first mature pod varies from 49 to 129 days after planting. In the context of global climate change and the shortening of the rainy season, such a descriptor is of high interest to the breeding community. Although it is important to capture diversity for today’s breeding interests, it is equally important to capture “neutral” diversity. Something that has no direct use for improvement today may become valuable in the future.

Since the 1980s, the development of molecular tools has had a substantial impact on biodiversity characterization. This fast-evolving tool provides increasingly efficient, precise, and cost-effective methods of managing collections. Where the combination of passport and phenotypic descriptors fails to identify duplicates, molecular methods provide a new tool for discriminating and identifying. It is also used to detect the potential loss of genetic integrity, whether associated to conservation or regeneration. IITA is presently fingerprinting the international collections of yam and cassava.

The genetic resources of one given crop are classified in three gene pools based on their respective compatibility/incompatibility to produce viable and fertile progeny (Harlan and de Wet 1971). Gene pool I includes the crop species itself and its wild progenitor. Gene pools II and III include other species that are related to yet different from the crop species of interest (Gepts 2006). Gene pool I is generally well represented in ex situ collections but gene pools II and III have often been neglected, although they represent a valuable reservoir of untapped genes as they evolved independently of human preferences.

Africa is a center of diversity for two of the crops maintained at IITA: cowpea (Vigna unguiculata) and yam (Dioscorea spp.) (Padulosi 1993, Orkwor et al 1998). IITA has devoted considerable resources for conserving the wild relatives of Vigna. However, efforts are still needed to further collect more wild relatives and cultivated cowpea. Although generally African biodiversity remains rich, various threats exist. Climate change attracts most attention in this matter but agriculture intensification should not be overlooked. The paradox is that research in agriculture requires diversity to build on existing traits but is one of the main threats to that vital biodiversity.

IITA is planning a collecting mission for cowpea in 2010 in regions of Nigeria where collecting had not been done and will focus on two species: V. unguiculata var. spontanea (gene pool I) and V. unguiculata subsp. baoulensis (gene pool II). Remi Pasquet, a taxonomist expert for cowpea from the International Centre of Insect Physiology and Ecology (icipe), will lead the expedition.

Researcher checks tissue culture-grown cassava. Photo by Jeffrey Oliver, IITA.
Researcher checks tissue culture-grown cassava. Photo by Jeffrey Oliver, IITA.

Over the last 30 years, there has been a profound change in the legal landscape with regard to ownership of biodiversity in general and crop genetic resources in particular (Gepts 2006). In the past, biodiversity was considered a common heritage of humanity, but in 1992, the Convention on Biological Diversity (CBD) assigned sovereignty over biodiversity to national governments. CBD is the first legally binding framework for the conservation of biodiversity that recognizes the “knowledge, innovations, and practices of indigenous and local communities and encourages the equitable sharing of benefits arising for the utilization of such knowledge, practices, innovation, and knowledge” (Shand 1997).

More recently, the International Treaty on Plant Genetic Resource for Food and Agriculture reconsidered the question of sovereignty over plant genetic resources. It promotes the exchange of germplasm for 64 crops in a multilateral agreement (multilateral system, MLS). Within this frame, the conservation of plant genetic resources, i.e., the future of food security, relies on shared initiatives and responsibility and the construction of a global system. Within this system, each stakeholder has a role based on comparative advantage—whether it is access to germplasm, technology, human resources, or capacity development.

The opening of the Svalbard seed vault in Norway, in 2008 is one of the building blocks of the global system. Such an initiative caught the attention of the media and, consequently, directed the attention of the world on the erosion of plant diversity. It is somehow reassuring to know that part (even a little) of plant diversity is now kept in a place that is naturally clean, cool (energy efficient), isolated (as the North Pole), and protected (by polar bears). However, not all plant diversity can be conserved in Svalbard. In fact, many species producing so-called recalcitrant seeds as well as those clonally propagated cannot be maintained at low temperatures for various physiological reasons. These problematic species, which in IITA’s collections include yam, cassava, and banana/plantain, are generally banked in the field or in vitro slow-growth conditions. The latter approach is preferred as it protects germplasm from field biotic and abiotic risks and allows easy access to distribution of clean material.

The ultimate in vitro conservation approach is cryopreservation (conservation at very low temperatures, generally at –196 °C). At such a temperature, all biochemical and biological processes are stopped. Thus, plant tissue can, in theory, be stored forever. IITA has recently developed such a process for cassava (Dumet et al. accepted).

Whatever the ex situ conservation approach, it will never be preferable to in situ conservation. However, whenever biodiversity preservation poses a threat to human livelihoods, comfort, or convenience, the politically expedient choice is usually to “liquidate” the natural capital (Ehrlich and Pringle 2008). It seems unlikely that more natural space will be available to ensure the safety of biodiversity in the future…This is not impossible, however, if the schools are involved in teaching the value of biodiversity to the younger generations.

Dumet, D., S. Korie, and A. Adeyemi. (accepted by Acta Horticulturae) Cryobanking cassava germplasm at IITA.

Ehrlich, P.R. and R.M. Pringle. 2008. Where does biodiversity go from here? A grim business-as-usual forecast and a hopeful portfolio of partial solutions. PNAS. Vol. 105, suppl. 1.

Eldregde, N. 1999. An original article.

Gepts, P. 2006. Plant genetic conservation and utilization: the accomplishments and future of a societal insurance policy. Crop Science 46:2278–2292.

Harlan, J.R. and J.M.J. de Wet. 1971. Towards a rational classification of cultivated plants. Taxon. 20:509–517.

Karp, A. 2002. The new genetic era: Will it help us in managing genetic diversity. In: Engels, J.M.M., V. Ramanatha Rao, A.H.D. Brown, and M.T. Jackson, eds. Managing Plant Genetic Diversity. Wallingford and Rome, CAB International and IPGRI, pp. 43–56.

Orkwor, G.C., R. Asiedu, and I.J. Ekanayake. 1998. Food yams: Advances in research, IITA and NRCRI, Nigeria.

Padulosi, S. 1993. Genetic diversity, taxonomy and ecogeographic survey of the wild relatives of cowpea (V. unguiculata). Ph.D. thesis, University of Louvain la Neuve, Belgium.

Shand, H. 1997.

Unlocking the diversity of yam

IITA scientists inspect yam plants in the field gene bank. Photo by O. Adebayo, IITA.
IITA scientists inspect yam plants in the field gene bank. Photo by O. Adebayo, IITA.

The International Year of Biodiversity (IYB) has emphasized the need for global action that will unravel the genetic diversity of yam, a root crop that provides food security to 300 million people in sub-Saharan Africa.

Yam is grown in about 51 countries in the tropics and subtropics, with yields averaging about 11 t/ha in the major producing countries of West Africa (Nigeria, Cote d’Ivoire, Ghana, and Bénin). However, little is known about the tuber crop’s diversity.

“This aspect is important for yam improvement to meet the demand of people depending on this crop for food and livelihood,” says Ranjana Bhattacharjee, IITA Scientist working on fingerprinting the yam germplasm collection.

Yam provides calories and puts money in the pockets of farmers. The tuber-bearing climbing plant from the genus Dioscorea also plays a major role in sociocultural activities in West Africa including traditional marriages and the New Yam Festival.

Globally, there are over 600 species of yam but only a few are cultivated for food or medicine. Scientists fear that some species are threatened and might become extinct as a result of climate change and genetic erosion. This prompts the calls for conservation.

The major edible species of African origin are white Guinea yam (D. rotundata Poir.), yellow Guinea yam (D. cayenensis Lam.), and trifoliate or bitter yam (D. dumetorum Kunth). Edible species from Asia include water or greater yam (D. alata L.), and lesser yam (D. esculenta [Lour.] Burkill). Cush-cush yam (D. trifida L.) originated from the Americas. White Guinea yam and water yam are the most important in terms of cultivation and use.

Yam tuber. Photo by IITA.
Yam tubers. Photo by IITA.

This preferred staple is usually eaten with sauce directly after boiling, roasting, or frying. The tubers may also be mashed or pounded into dough after boiling, or cooked with sauces and oils. They can be processed into yam balls, chips, and flakes.

Fresh yam tubers are peeled, chipped, dried, and milled into flour that is used in preparing dough called amala (Nigeria) or telibowo (Bénin). Commercial products based on dry flakes or flours from the tuber are produced in Nigeria, Ghana, and Côte d‘Ivoire for export and sale in urban areas.

Though millions depend on the crop, especially in sub-Saharan Africa, not many outside of Africa know about the tuber’s potential for commercialization, and its role in enhancing food security in the region, according to Robert Asiedu, Director of the Program on Root and Tuber Systems at IITA.

“We talk about yam tubers as a food staple of millions of Africans to donors or investors who don’t even know what yam is, how it looks or tastes. So the question is: How would they even think of investing in research in a ‘little-known’ staple like yam?”

Perhaps yam’s low profile in the developed countries or in the West is the major limitation in attracting funding for research, but this hardy tuber is an important “part of man” especially in Africa, the Caribbean, Asia, and the South Pacific Islands where it is widely eaten. According to Asiedu, it is the “preferred and most appreciated staple food and calorie source” in areas where it is grown.

Yam faces constraints that include the high costs of planting material and of labor, decreasing soil fertility, the inadequate yield potential of varieties, and increasing levels of field and storage pests and diseases associated with intensive cultivation.

To tackle some of these constraints, work at IITA for the last few years has focused on improving the tuber, primarily white and yellow Guinea yam, and water yam.

Man with huge yam tuber. Photo by IITA.
Man with huge yam tuber. Photo by IITA.

The breeding program uses the 2,216 accessions of Guinea yam and 816 of water yam in IITA’s genebank to study resistance to anthracnose and virus diseases. Improved populations have been developed with partners in the national agricultural research and extension systems (NARES), who have released varieties in Nigeria (National Root Crops Research Institute, 7) and Ghana (Crops Research Institute, 3).

Despite the success in yam improvement, new challenges keep on coming, prompting researchers to use other tools, such as molecular characterization to unlock the genetic diversity of yam.

Recently, the Global Crop Diversity Trust funded a project in IITA to duplicate, document, and distribute the germplasm of yam to other partners in accordance with the International Treaty on Plant Genetic Resources for Food and Agriculture. Such support is indeed a milestone in yam research. The project also aims to fingerprint the entire germplasm collection at IITA. This will help in understanding the extent of genetic diversity present in the collection. From this, the genes for important traits can be determined through association mapping, a tool that could be used successfully to improve and sustain the crop.

As the world marks the IYB, serious attention from other donors is necessary to keep the crop as a “part of man.”

Safeguarding local varieties ensures food security

Cassava pile after harvest. Photo by IITA.
Cassava pile after harvest. Photo by IITA.

Cassava is a food security crop to more than 600 million people in the developing world, providing incomes to resource-poor farmers, improving their livelihoods, and serving as a buffer against food crises.

The strategic importance of cassava, however, is being threatened, especially in Africa, as local varieties are in danger of disappearing because of genetic erosion and other human and natural factors.

“In Guinea, for instance, about seven local cassava varieties are fast disappearing. This is risky, especially for cassava since it is a clonal crop,” according to Paul Ilona, IITA Senior International Trials Manager. Clonal crops are those propagated through cuttings or other plant parts, not by seeds.

Genetic erosion is a process whereby the already limited gene pool of an endangered species of plant or animal diminishes even more when individuals from the surviving population die out without getting a chance to breed within their endangered low population.

Both local and improved cassava varieties alike create a robust gene pool, offering choices for breeders in future breeding programs. However, the loss of genes from the extinction of some local varieties could limit future improvement programs. The endangered varieties may hold key traits that could offer possible solutions to hunger and poverty in the future.

Woman selling cassava, local market, Nigeria. Photo by IITA.
Woman selling cassava, local market, Nigeria. Photo by IITA.

To prevent the genetic erosion of cassava, IITA and the Institut de Recherche Agronomique de Guinée (IRAG) have stepped up efforts to save native African varieties with the collection of 73 local varieties from Guinea, West Africa.

These varieties are now conserved under ex situ conditions at IITA’s Genetic Resources Center (GRC) in Ibadan, Nigeria. They form part of a collection to safeguard the continent’s plant genetic resources. The collecting mission in that West African country last year was funded by the Global Crop Diversity Trust (GCDT), IRAG-Guinea, and IITA.

“The conservation of local varieties provides hope for future cassava breeding programs and helps to guarantee food security in Africa,” says Dominique Dumet, GRC Head and coordinator of the collecting mission.

Ilona says the loss of native cassava varieties might limit the number of genes available for breeders to work with. “For breeders, any time we lose (crop) genes, it hurts. That is why the conservation of local cassava varieties at GRC is important to us,” he says.

Apart from cassava, the IITA-GRC holds over 25,000 accessions of major African food crops, including cowpea, yam, soybean, bambara nut, maize, and plantain/banana. IITA shares these accessions without restriction for use in research for food and agriculture.

The collecting mission makes Guinea the fourth country, after Angola, Togo, and Bénin, to allow IITA to collect and share their germplasm with other countries, since the International Treaty on Plant Genetic Resources for Food and Agriculture went into force in June 2004.