Cryopreservation of Chrysanthemum cinerariaefolium shoot tips. Effects of pretreatment conditions and retention of biosynthetic capacity

A simple and efficient method for cryopreservation of Chrysanthemum cinerar iaefolium shoot tips is described. It comprized: treatment of the explanted stem apices for 3 d in proliferation medium enriched with 0.55 M sucrose, incubation for 1 h in medium with 7.5% DMSO, transfer to cryotubes, direct immersion in liquid nitrogen, rewarming at 40 degrees C and culture of shoo t tips on solidified nutrient medium containing II CIM ANA and 4.5 CIM BAP. The average viability rate of cryopreserved apices was 62%. Dehydration of tissue cells prior to freezing with sucrose was found to be more effective than dehydration under sterile air flow for stem apices with high moisture content. The morphogenic potential of frozen stem apices and the total chl orophyll and pyrethrin contents of regenerated plants were preserved after the different treatments.