Phytosanitary interventions for safe global germplasm exchange and the prevention of transboundary pest spread: The role of CGIAR germplasm health units

 P. Lava Kumar, Maritza Cuervo, J. F. Kreuze, Giovanna Muller, et al.   |  

The efforts of GHUs in thoroughly testing germplasm accessions for known pests, before their release for international transfer, have averted the inadvertent spread of quarantine pests. This is of great significance, as most CGIAR centers operate in countries where some of the most dreaded pests are prevalent (e.g., cassava brown streak virus, Karnal bunt, maize lethal necrosis, rice blight, and wheat blast, to name a few).

The international exchange of genetic resources, such as botanic seeds and vegetative propagules, has played a crucial role in agricultural and food diversification to an extent that about 68% of national food supplies are derived from crops with a foreign origin. At the forefront of these international exchanges are the CGIAR genebanks, breeding and seed system programs that have made vital contributions for over five decades by assembling germplasm from all over the world for conservation, and adding value to those materials by characterizing, breeding, and making them available to users around the world.

Established in 1971, the CGIAR is part of the global agricultural research system, which makes critically important contributions to the United Nations Sustainable Development Goals (SDGs) in alleviating poverty and hunger and improving food and nutrition security and in the conservation of biodiversity. The 11 CGIAR genebanks conserve over 760,467 accessions of cereals, grain legumes, forages, tree species, root and tuber crops, and bananas.

These represent >174 genera and over 1000 species obtained from 207 countries, which are conserved in 35 collections around the world as seeds, in vitro material, and living plants in fields or screenhouses. Between 2007–2016, the CGIAR centers distributed 3.91 million samples, with about 30% from genebanks and 70% from crop breeding programs, to 163 countries.

These distributions from the CGIAR programs account for almost 89% of the total annual international germplasm exchanges (“exchange” and “transfers” used as a common term to denote germplasm exports or imports between countries.), under the International Treaty on Plant Genetic Resources for Food and Agriculture.

Between 2010 to 2019, the CGIAR genebanks acquired 116,921 distinct accessions, about 35% of which were acquired through the centers’ own breeding programs and 65% were acquired from collection missions or through national programs in 142 countries. During the same period, the CGIAR genebanks distributed, on average, 115,000 samples of germplasm per year, and above 80% of the recipients were in developing countries. A detailed analysis of the CGIAR genebanks’ acquisition and distribution of germplasm in the last decade is presented by Halewood et al.

The demand for a global movement of plant genetic resources (PGR) from the international genebanks and breeding programs is increasing due to worldwide efforts to develop nutrient-rich high-yielding varieties, which are resilient to biotic and abiotic stresses and better adapted to a changing climate, through various programs, such as the CGIAR’s ‘Crops to End Hunger’ initiative. Import and export of germplasm and other biological resources are influenced by several international and national policies, treaties, and legal frameworks.

The ITPGRFA and its multilateral system of access and benefit-sharing and the Convention on Biological Diversity (CBD) agreements guide the CGIAR centers’ policies on germplasm acquisition, conservation, regeneration, use, and distribution. The availability of pestand disease-free germplasm is an important requirement for international distribution from genebanks and breeding programs.

It is well-known that plants and seeds can harbor pathogens and pests including bacteria, fungi, phytoplasmas viroids, viruses, insects, nematodes, and other harmful biotic agents, and that the transfer of germplasm carries a simultaneous risk of moving pests between geographies and introducing them into territories where they are not known to exist.

International seed transfers have been recognized as important pathways for the transboundary spread of pests through human activities associated with collection and distribution. The threat may become severe, if more virulent strains or races of the pathogens are introduced. Even pests with a low seed transmission rate, especially viruses, may lead to the development of an epiphytotic proportion of the disease in a field, if the other conditions (e.g., occurrence of insect vectors and susceptible hosts) and climate are favorable.

The introduction of economically important alien pests, a term used for non-indigenous pests introduced into new territory, from their centers of origin into new environments, has been reported in many different parts of the world [14]. Considering that every plant serves as a host for several insects and microbes of both a beneficial and harmful nature, every introduction of plant material is expected to result in the introducing exotic organisms.

The CGIAR germplasm health program has over 50 years of experience. GHUs have served as a vital conduit of the globally coordinated CGIAR crop research programs, which tested 1000s of germplasms and new breeding lines in multiple field sites and mega environments for the identification of lines that have superior yields, high nutrition, and are resilient to biotic and abiotic stresses. The seeds of those accessions were made widely available for crop productivity improvement, leading to a broad social, economic, and environmental impact.

For instance, the International Wheat Improvement Network (IWIN) organized approximately 700 field sites in over 90 countries to develop around 1000 high-yielding, disease-resistant lines targeted at major agro-ecologies, which are delivered annually as international public goods (IPGs). To date, GHUs continue to facilitate crucial germplasm transfers to the largest number of stakeholders around the world vital to deliver IPGs with a positive impact on the SDGs associated with

(i) nutrition and food security;
(ii) poverty reduction;
(iii) environmental health and biodiversity; and
(iv) climate adaptation and greenhouse gas reduction.

The efforts of GHUs in thoroughly testing germplasm accessions for known pests, before their release for international transfer, have averted the inadvertent spread of quarantine pests. This is of great significance, as most CGIAR centers operate in countries where some of the most dreaded pests are prevalent (e.g., cassava brown streak virus, Karnal bunt, maize lethal necrosis, rice blight, and wheat blast, to name a few).

Years of experience indicate that adaptability is a vital requirement for sustaining operations in an era of constant changes driven by pest outbreaks, agricultural intensification, climate variability, phytosanitary policies, and regulations. A study on the patterns of invasion and spread pathways of 1517 invasive species reported that horticulture and the nursery trade are the dominant pathways for the incursion of invasive alien species.

The increasing international exchanges and the globalization of the world present a high risk that introduced pests will be established and expand quickly. Safe and efficient germplasm transfer forms a critical preventive pest control approach for the CGIAR programs under the IPPC treaty and national laws. It is also safe to assume that the drivers responsible for transboundary pest outbreaks are difficult to contain, and high levels of vigilance will be required to monitor the pest dynamics in order to sustain the CGIAR operations.

This requires regular updating of the existing protocols for hitherto unknown pests, enhanced collaboration with phytosanitary organizations and academia to obtain the most advanced information on pest detection and epidemiology, and adequate funding support, which is necessary for continuous adaptation to new pest challenges. It is imperative for GHUs to leverage technological advances in diagnostics, ICTs, remote sensing, and modeling to predict and monitor pest dynamics at a global level in order to understand their dispersal mechanisms and impact on the genebank and breeding programs in the short, medium, and long term.

GHUs high-level capacity, experience, track record, and global distribution in the developing world enable them to play an important role as centers of excellence in supporting national and regional pest and disease surveillance and rapid response. A strong case exists for positioning GHUs as part of a global network of phytosanitary hubs for the research, diagnoses, and control of established and emerging pests as part of the One CGIAR program, which is set to be operational in 2022

Read the study:
Kumar PL, Cuervo M, Kreuze JF, Muller G, Kulkarni G, Kumari SG, Massart S, Mezzalama M, Alakonya A, Muchugi A, Graziosi I, Ndjiondjop M-N, Sharma R, Negawo AT. (2021) Phytosanitary Interventions for Safe Global Germplasm Exchange and the Prevention of Transboundary Pest Spread: The Role of CGIAR Germplasm Health Units. Plants. 2021; 10(2):328. 

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