Cryopreservation of potato microtubers: the critical roles of sucrose and desiccation

Abstract

Microtubers are an important source of tissues for conservation and exchange of germplasm. An efficient method for cryopreservation of whole microtubers that will ensure a safe and long-term storage was developed in this study. Potato cultivars (Climax, Avon and Ceza) were evaluated for responses to in vitro tuberization and cryopreservation. Treatments include pretreatment on medium with sucrose (30–100 g l−1) and desiccation in silica gel (0, 3 and 6 h) followed by rapid plunging into liquid nitrogen (LN). There were significantly higher number of microtubers produced on the medium with 80–100 g l−1 sucrose (8–11.33) compared to 30 g l−1 sucrose (0.7–1.7). The microtuber fresh weights varied among genotypes on sucrose (80–100 g l−1) with ‘Climax’ showing the highest value followed by ‘Avon’ and ‘Ceza’. The microtuber moisture content ranged from 26 to 36 % after 3 h of desiccation and from 17 to 28 % after 6 h of desiccation for all three cultivars. After cryopreservation, the percentage of surviving (green) microtubers of ‘Climax’ increased with an increase in sucrose concentration, and was significantly higher than the control. For ‘Avon’, the percentage of green microtubers produced on sucrose (80–100 g l−1) was significantly higher than other treatments. Also, ‘Ceza’ produced significantly more green microtubers with 100 g l−1 sucrose compared to other sucrose treatments, similar to the control. Cryopreserved microtubers produced the most shoots on medium with 100 g l−1 sucrose. This study demonstrates the feasibility of long term storage of microtubers in LN for conservation purposes.