Major research challenges and directions for future research

Abstract

The various strategies and methods available for in situ and ex situ conservation of plant diversity should be used in a complementary manner to optimize and secure the conservation of a given genepool. A lot of collecting remains to be performed before valuable germplasm is lost, both for crops and their wild relatives. Despite the fact that numerous challenges still exist, a number of new tools are now available to improve collecting efficiency. In situ/on farm conservation is of high relevance for tropical plant species, especially for those with non-orthodox seeds and vegetatively propagated ones. In situ/on farm conservation will become more efficient when communities, farmers and local organizations are more directly involved in research and implementation activities, and when researchers and funding agencies fully realize the importance and relevance of this conservation approach. Conservation of orthodox seeds is the most widely practised method of ex situ conservation of plant genetic resources. Yet, it is faced with important challenges, which relate to the observation that longevity of seeds of a large number of species stored under standard genebank conditions is shorter than anticipated previously. This calls for research in seed thermodynamics at low temperature and strongly advocates for the systematic cryogenic storage of one sub-sample of every genebank accession. For in vitro slow growth storage, the main challenges are to improve the introduction and maintenance of contaminant-free plants in culture, and to find the appropriate growth media for suitable micropropagation, which may have to be customized to improve the response to storage of unique plant groups. Cryopreservation is much more advanced for vegetatively propagated plants, in comparison with recalcitrant species, because of many of their characteristics and because most of them are wild species, with no or little information on their biology or storage behaviour. Challenges to improve the cryopreservation of recalcitrant species include the prerequisite development of in vitro culture protocols for the explants used, the necessity to dehydrate the tissues as rapidly as possible before immersion in liquid nitrogen and to reduce the damage caused by the burst of reactive oxygen species, which occurs during dissection and desiccation. The range of analytical tools, which allow better understanding of the biological and physical processes occurring during cryopreservation of plant tissues and organs, is increasing. Such tools will not only increase our knowledge but also lead to more efficient cryopreservation protocols for problem materials. It should be realized that countries rely on each other for access to genetic resources for agricultural development. This interdependency calls for increased collaboration among countries to fully support, participate in and implement the various treaties, conventions and agreements, which aim at the effective conservation and sustainable use of biological diversity essential for food and agriculture at the global level.