Cryopreservation of citrus seed via dehydration followed by immersion in liquid nitrogen

Abstract

An important method for plant germplasm conservation is offered by a biotechnology-based approach of cryopreservation. Cryopreservation refers to the storage of plant material at ultralow temperatures in liquid nitrogen. A procedure for cryopreservation of polyembryonic seeds was improved for selected citrus cultivars from Turkey. Seed dehydration was performed at different exposure times, in sterile conditions of a laminar flow-hood. The tested cultivars showed the highest tolerance to low temperature storage when the seeds were first dehydrated to a moisture content of 21.8% for Poncirus trifoliata Raf. x Citrus sinensis Osb. and to 17.6% for Citrus limonia Osbeck. The postcryopreservation germinability ranged from 73.3% (Poncirus trifoliata Raf. x C. sinensis Osb. and Fortunella margarita (Lour.) Swingle) to 93.3% (C. jambhiri Lush.). Dehydration was beneficial for germination of seeds from all of the tested citrus species after the liquid nitrogen exposure. Seedlings derived from cryopreserved seeds had well-formed shoots and roots and were easily acclimated to greenhouse conditions.