Effect of cold storage on somatic embryogenesis systems of Camellia

Abstract

The effects of short-to medium-term cold storage (3-4°C) on the maintenance of embryogenic capacity and the germination and conversion of somatic embryo cultures of Camellia were investigated. Four culture lines maintained by repetitive embryogenesis were used: three C. japonica lines and one C. reticulata cv. Mouchang line. Increasing cold storage time (3, 6, 9, and 12 months), decreased the frequency of surviving embryo clusters and the mean number of surviving embryos per cluster. Eight week old embryogenic cultures were stored for one or two months, after which secondary embryos were isolated from the parent embryos and transferred to the germination medium. Two months of chilling significantly improved plantlet conversion abilities of secondary embryos, with rates ranging from 76–100% (depending on the embryogenic line) against 32–65%, respectively, in the absence of cold treatment. The incidence of secondary embryogenesis during germination also decreased after cold treatment. Cold storage of somatic embryos of Camellia reduced their competence for secondary embryogenesis while it increased their capacity for conversion to plantlets. These effects appear to reflect a general cold-induced increase in the maturity of the embryos.