Cryopreservation of recalcitrant (i.e. Desiccation-sensitive) seeds

Abstract

Unlike orthodox seeds, mature seeds of some species do not survive desiccation and are often referred to as recalcitrant (Hong et al. 1998). Approximately 10-20% of angiosperm species produce seeds that acquire some, but not full, tolerance of desiccation during maturation (Dickie and Pritchard 2002). Incidence of recalcitrance does not distribute along phylogenetic clades, though some plant families include many species producing recalcitrant seeds (e.g., Fagaceae, Lauraceae, Sapindaceae, Meliaceae) while other families apparently lack species exhibiting this trait (e.g., Solanaceae, Asteraceae, Amaranthaceae). Life history traits of the plant, such as a long lived, perennial nature, and its habitat, such as aquatic or rainforest, are associated with seed recalcitrance, but not all plants with these characteristics produce recalcitrant seeds. The term recalcitrant is also used to describe seeds that are particularly difficult to germinate because they have deep dormancy or an unknown dormancy release mechanism. Though frustrating to work with, seeds with this dormancy physiology are amenable to cryopreservation using straightforward procedures described for orthodox seeds and will not be addressed here.