Submitted to: Seeds International Workshop Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 5/11/2002
Publication Date: 5/11/2002
Citation: Mirian E.TS., C. Walters R.B. Reis, and L.M. Hill. 2002. Conservation of genetic resources of coffee using cryopresvation. 7th International Workshop on Seed Biology, May 11-19, 2002, Salamanca, Spain. Interpretive Summary: This work contributes to the effort to cryopreserve coffee germplasm. The work is done in collaboration with Embrapa Genetic Resources and Biotechnology. Currently coffee genetic resources cannot be placed in seed banks. This work is the first report of survival of coffee seeds following liquid nitrogen exposure. The rate at which seeds are cooled and warmed seems critical to survival.
Technical Abstract: Conservation of genetic resources of Coffea, a genus of economic importance worldwide, is difficult because Coffea seeds do not survive conventional seed sotrage protocols. Most coffee germplasm is maintained in field collections, which are expensive to maintain and susceptible to natural disasters or disease. Storing Coffea seeds in genebanks would reduce costs and provide a safer conservation strategy for these important genetic resources. The seeds of Coffea species show a range storage physiologies. Though not completely tolerant of drying, embryos from most Coffea species studied survived water contents as low as or less than 0.20 g water /g dry mass. This relatively high tolerance of desiccation suggests that seeds and embryos can be cryopreserved if both water content and cooling and heating rates are optimized. Consistent with this hypothesis, no loss of viability was observed when Coffea arabica seeds were dried to 0.20 g/g (in equilibrium with 75% RH) and cooled to LN at rates of 96 degrees C/min. Relatively rapid warming from LN was also necessary, as seeds warmed at 25 to 30 degrees C/min survived and seeds warmed at 6 to 7 degrees C/min did not survive. These cooling and warming rates were achieved by hermetically sealing (10-11g or 50 seeds) in foil-laminate bags and plunging bags directly into LN containers and placing bags removed from LN directly into a 40 degrees C bath. Coffea seeds with optimized water contents did not survive if bags were placed in LN vapor (cooling rates of 10 to 40 degrees C/min) or thawed on the bench (warming rates of 7 degrees C/min). Successfully cryopreserved Coffea arabica seeds showed minimal viability loss after one-year storage in liquid nitrogen. We are using that protocol to store coffee seeds at the genebank of Embrapa Genetic Resources and Biotechnology, in Brazil.