Challenges and Prospects for the Conservation of Crop Genetic Resources in Field Genebanks, in In Vitro Collections and/or in Liquid Nitrogen

Abstract

The conservation of crop genetic resources, including their wild relatives, is of utmost importance for the future of mankind. Most crops produce orthodox seeds and can, therefore, be stored in seed genebanks. However, this is not an option for crops and species that produce recalcitrant (non-storable) seeds such as cacao, coffee and avocado, for crops that do not produce seeds at all; therefore, they are inevitably vegetatively propagated such as bananas, or crops that are predominantly clonally propagated as their seeds are not true to type, such as potato, cassava and many fruit trees. Field, in vitro and cryopreserved collections provide an alternative in such cases. In this paper, an overview is given on how to manage and setup a field, in vitro and cryopreserved collections, as well as advantages and associated problems taking into account the practical, financial and safety issues in the long-term. In addition, the need for identification of unique accessions and elimination of duplicates is discussed. The different conservation methods are illustrated with practical examples and experiences from national and international genebanks. Finally, the importance of establishing safe and long-term conservation methods and associated backup possibilities is highlighted in the frame of the global COVID-19 pandemic.

Plant Biodiversity and Genetic Resources Matter!

“…For other crops that do not produce orthodox seeds with desiccation and low temperature tolerance, or do not produce seeds at all, or are generally clonally propagated as seeds are not true-to-type, different conservation options are available. Those crops can be safely conserved in field genebanks, through in vitro culture or cryopreservation [5]. Crop wild relatives of the secondary and tertiary genepool are mostly found in the wild and are rather difficult to conserve ex situ.…”

“…This can be achieved through in situ conservation of CWR in their natural habitats or through the continuous use of landraces by farmers on their own farm, and thus maintaining the evolutionary processes that result in adaptation. However, due to the alarming rates of genetic erosion in nature, it is critically important to complement in situ conservation with ex situ conservation in genebanks-either as dried seeds with low seed moisture content (3-7%) at freezing temperatures (amenable for orthodox seeds) [4], or in field genebanks, through in vitro culture or cryopreservation (rapid freezing and storage at extremely low temperatures) [5]. The latter concerns crops that do not produce orthodox seeds with desiccation and low temperature tolerance (recalcitrant seeds; e.g.…”

“…The latter concerns crops that do not produce orthodox seeds with desiccation and low temperature tolerance (recalcitrant seeds; e.g. avocado), or do not produce seeds at all as is the case for bananas, or are generally clonally propagated, as seeds are not true-to-type as for instance potato [5]. It should be noted that ex situ approaches 'freeze' the genetic diversity, as no (or very limited) possibilities for adaptive evolutionary processes take place.…”

“…This Special Issue comprises 32 papers covering a wide array of aspects from the definition and identification of hotspots of wild and domesticated plant biodiversity [8] to the specifics of the conservation of crop germplasm and their wild relatives in situ and ex situ, including germplasm and genebank management and genebank phenomics, to enhance the value and utilization of crop germplasm in breeding. The various modes of ex situ germplasm conservation in the form of orthodox seeds, as in vitro collections and/or in liquid nitrogen, have been described [5], and special attention has been drawn to the importance of seed physiology for the successful long-term conservation of orthodox seeds [4]. One paper assessed the specific case of seed germination after 30 years of storage in permafrost [16].…”

Phytosanitary Interventions for Safe Global Germplasm Exchange and the Prevention of Transboundary Pest Spread: The Role of CGIAR Germplasm Health Units

“…Banana (and plantain), cassava, potato, sweetpotato, and yam are the major vegetatively propagated crops (VPCs) exchanged by the CGIAR programs [ 55 ]. Vegetatively propagation poses the greatest risk of the introduction of pests through planting material, which can carry any infections from previous seasons to the next cropping cycle and thus accumulate pathogens, especially viruses, over generations of cultivation.…”