The optimal moisture content for cryopreservation of Longjing tea seeds.

Abstract

Background: Most plant species produce seeds that can be dried to c. 3-7% moisture content, i.e., orthodox, and successfully stored in liquid nitrogen. However, tea seeds are often described as recalcitrant, i.e., they die when to lower moisture levels safe for cryopreservation.

Objective: In this study, we investigated the tolerance to desiccation and freezing of Longjing tea (Camellia sinensis) seeds and analyzed the reason behind seed mortality during desiccation and cryopreservation.

Materials and methods: We analyzed the desiccation capacity of tea seeds from Hangzhou, China and subjected the desiccated seeds to programmed cooling and thermal analysis using differential scanning calorimeter (DSC). Subsequently, we used the exotherms to determine the frozen and unfrozen water. We analyzed seed germination and seedling establishment at different water content after storing seeds in liquid nitrogen and correlated the survival with the bound and unbound water.

Results: Results showed that the seeds could tolerate drying to 7.9 % moisture content without significant viability loss. Moreover, the germination percentage declined sharply after cryopreservation, and the lowest moisture content at which a normal seedling could develop was 11.3+/-1 %, although seeds dried to lower MC did germinate but did not grow into the seedling phase.

Conclusion: Longjing tea seeds used in this study were neither orthodox nor recalcitrant. We show that the interaction between lipids and freezable water in seeds may lead to the cryoinjury. https://doi.org/10.54680/fr24610110612.