Effect of Cryopreservation Method Supported With Biochemical Analyses in the Axillary Bud of Jewel Orchid, Ludisia Discolor

Abstract

This study was conducted to investigate the potential of conserving an endangered terrestrial jewel orchid Ludisia discolor using in vitro grown axillary buds. Excised segments of axillary buds (4 - 5 mm in length) were precultured on a modified Murashige and Skoog (MS) medium supplemented with 0.2 M sucrose for 24 h and osmoprotected in a loading solution for 20 min. Then, axillary buds were dehydrated in PVS2 solution for 10 min at 0°C and incubated in liquid nitrogen for 1 h. Subsequently, axillary buds were rewarmed rapidly by dilution solution and transferred to a growth recovery medium supplemented with 0.05 µM melatonin under in vitro conditions that led to an improved survival chance (16.67%) for cryopreserved L. discolor. The abiotic stresses and the overproduction of reactive oxygen species (ROS) during cryopreservation stages may contribute to cryoinjuries and poor survival. The varied response towards stress was detected with significantly increased values recorded at certain cryopreservation stages, including proline activity at the dehydration stage (5.51 µmol/g), catalase at the preculture (85.64 U/g) and dehydration (70.87 U/g) stages, peroxidase at the rewarming stage (565.37 U/g) and ascorbate peroxidase during the loading stage (12.19 U/g). Hence, this first attempt to cryopreserved L. discolor indicates that future experimental designs could include exogenous antioxidants and different vitrification solutions to improve survival and regeneration.