Improved Conservation of Coffee (Coffea arabica L.) Germplasm via Micropropagation and Cryopreservation

Abstract

Coffee (Coffea spp.) is an important tropical agricultural crop that has significant economic and social importance in the world. The ex situ conservation of plant genetic resources through seeds is not feasible due to the sensitivity of coffee seed to desiccation and low temperatures. The cryopreservation of zygotic embryos may allow for an efficient and long-term storage of coffee germplasm. This study describes the cryopreservation methods for conserving zygotic embryos of Coffea arabica L. for the long-term conservation of currently available germplasm. Zygotic embryos were successfully cryopreserved in liquid nitrogen at −196 °C under controlled environmental conditions with either droplet-vitrification or encapsulation–vitrification protocols without dehydration. Zygotic embryos had the highest regrowth (100%) following droplet-vitrification cryopreservation using the Plant Vitrification Solution 3 (PVS3) for 40 min at 23 °C. In the case of encapsulation–vitrification using PVS3 for 40 min at 23 °C, the embryo regeneration response was 78%. Plantlets were recovered following shoot multiplication using a temporary immersion system (TIS) and in vitro rooting. The prolific rooting of shoots was observed after 4 weeks of culture in the liquid medium with plugs made of the inert substrate Oasis® In vitro Express (IVE) compared to the semi-solid medium. The successful cryopreservation of coffee zygotic embryos using droplet vitrification and encapsulation–vitrification followed by micropropagation in temporary immersion culture system has not been reported earlier and together these technologies are anticipated to further facilitate the initiatives for the conservation and distribution of coffee germplasm.