Shin-Ichi Yamamoto, Genetic Resources Center, National Agriculture and Food Research Organization (NARO)
The National Agriculture and Food Research Organization (NARO) conducts Genebank Project for collecting, conserving, evaluating, multiplying and distributing plants (228,198 accessions), microorganisms (35,407 acc.), animals (1,971 acc.) and DNA materials (394,440 clones) related to agriculture since 1985. The Genetic Resources Center, NARO (NGRC) coordinates this activity in collaboration with a network of institutes (so-called sub-banks) throughout Japan. In the plant section of the project, orthodox seeds are conserved in a seed storage at -18 ℃ for long term and at -1 ℃ for medium term, respectively. Approximately 30,000 accessions of plant genetic resources are clonal crops. They are basically conserved in fields or greenhouses of sub-banks and very useful for immediate use. However, the construction of cryobank will contribute significantly to the cost-effective long term preservation of vegetatively propagated crops in a stable manner in safe and disease-free conditions as safe backup. In NGRC, winter dormant buds of 1,283 mulberry accessions have been cryopreserved. But this method cannot be available for the crops which do not form dormant buds. Although existing cryopreservation methods such as vitrification and droplet methods for in vitro shoots can be applicable for those crops, more systematical protocol is desirable for facilitating cryobank for them. Therefore, we developed efficient and simple cryopreservation procedures, V and D cryo-plate procedure using small hard aluminum plates with micro-wells. These methods have many advantages such as simple handling, high regrowth rate, very high cooling and warming rate, easy learning and so on. We already started to preserve clonal plant genetic resources such as potato (310 acc.), mat rush (181 acc.) and so on by these methods in NGRC liquid nitrogen tanks. We plan to increase accessions stored systematically and establish a cryobank project in Japan.