Advanced Technologies for Germplasm Conservation of Tropical Fruit Species

Abstract

Tropical fruit species are important worldwide and contribute to human nutrition, environmental protection and income generation. In the Asia, Pacific and Oceania region there are more than 400 tropical fruit species. However, many are subject to genetic erosion and their conservation is difficult or impossible by traditional methods due to seedlessness, recalcitrance, or short seed life. We developed conservation techniques, including in vitro protocols and cryopreservation, for major tropical fruit species in the collaborating countries. Protocols for vitrification-based shoot tip cryopreservation have been refined and applied to many papaya genotypes and Vasconcellea pubescens. Papaya seed has been stored for 12 months at a range of moisture contents and temperatures including cryostorage and was germinated after GA3 treatments. Somatic embryogenesis has been refined for mango and somatic embryos have been recovered after cryopreservation. Protocols for plantlet growth in vitro were achieved for two species of Nephelium. Shoot proliferation has been achieved for litchi and longan. Micropropagation and cryopreservation of embryogenic axes have been achieved for persimmon. Micropropagation protocols via adventitious shoot induction, microcutting or somatic embryogenesis were developed for seven Asian and three native Australian Citrus species. Seed/embryonic axes desiccation/ encapsulation-dehydration and vitrification of shoot tips/embryonic axes were employed for cryopreservation of citrus. Micropropagation and organogenesis have been achieved for three Australian native Davidsonia spp.