Tolerance to Desiccation and Cryopreservation of Seeds of Seven South American Ilex Species

Abstract

This research aimed at evaluating the desiccation tolerance and ability to withstand cryostorage of intact seeds of seven South American Ilex species, and comparing different methodologies for in vitro germination of fresh and cryostored seeds. Intact seeds were silica gel–desiccated from 2 to 14 hours, placed in cryovials, and immersed in liquid nitrogen (LN). Survival was assessed through in vitro germination of intact seeds, bisected seeds, or isolated embryos. Seeds of the seven Ilex species (Ilex brasiliensis (Sprengel) Loes., Ilex brevicuspis R., Ilex dumosa var. dumosa R., Ilex integerrima (Vell. Conc.) R., Ilex paraguariensis A. St. Hil., Ilex pseudoboxus R., and Ilex theezans R.) tolerated desiccation to ≈6% moisture content (MC) and could be successfully cryopreserved when MC decreased between 6.4% and 8.4% depending on the species, before immersion in LN. In addition, it was established as the optimal condition for in vitro seed germination of the seven Ilex species. A simple and cost-effective cryogenic procedure (which did not require the use of cryoprotectants or sophisticated facilities) was defined for seeds of seven Ilex species, which provides a new alternative for safe long-term preservation of Ilex germplasm.