Methods of Thermal Analysis as a Tool to Develop Cryopreservation Protocols of Vegetatively Propagated Crops

Cryopreservation is considered to be a reliable biotechnological tool for the long-term conservation of vegetatively propagated plant germplasm. The technique is based on freezing plant tissues at an ultralow temperature. However, high water content in plant tissue can result in injury during the cooling and thawing processes. Water behavior in the process of cryopreservation can be assessed by the use of thermal analysis method. This chapter demonstrates how the use of heat flux-type differential scanning calorimetry (DSC) thermal analysis methods such as standard DSC, tem-perature-modulated DSC (TMDSC), and quasi-isothermal temperature-modulated DSC (QITMDSC) can be used to assess the amount of freezable water and verify if the tissue being used has reached glass transition as well as analyzing the thermal events during cooling and freezing to reduce crystallization and damage by frost. Here, you can find a guide on how these thermal analysis methods can be applied, through concrete examples of each method and their use in the development of a more reliable and precise cryopreservation protocol for vegetatively propagated plant species. calorimeter during warming. The glass transition is characterized by the beginning of the heat flow change (onset), midpoint (in some cases inflection point), and finish of heat flow change (endset), characterized by change of heat capacity ( Δ Cp). Crystallization of supercooled water is an exothermic reaction, followed by the thawing of crystalized water. These events can be characterized by onset, midpoint, and endset temperatures and by event heat flow change. Based on analysis of the exothermic or endothermic events, the freezable water content can be calculated also in dehydrated samples. Additionally, this thermal analysis method is a powerful tool in the assessment of the sample’s water behavior during cooling and warming; this includes supercooling, freezing, glass transition, cold crystallization, and melting which influence the sample’s cryopreservation success.