Development of a PVS2 droplet vitrification method for potato cryopreservation

Area of Science:

• Plant science
• Cryobiology
• Germplasm conservation

Background:

• The International Potato Center (CIP) stewards the world's largest in vitro potato collection.
• Current in vitro conservation is efficient for ~2 years but not ideal for long-term storage due to costs and risks.
• Field conservation poses risks of genetic erosion and is less secure than in vitro methods.

Purpose of the Study:

• To enhance the potato cryopreservation protocol utilizing droplet PVS2 vitrification.
• To establish a more secure and efficient long-term conservation strategy for potato germplasm.

Main Methods:

• Apical shoot tips (1.8-2.5 mm) from 3-week-old cultures were used.
• Treatment involved exposure to loading solution (15 min) and PVS2 (50 min at 0°C).
• Ultra-rapid cooling in liquid nitrogen (LN) followed by rewarming in 1.2 M sucrose MS medium and gradual sucrose reduction during post-cryo culture.

Main Results:

• The droplet PVS2 vitrification method demonstrated superior survival and recovery rates.
• Diverse potato cultivars, including frost-tolerant (Solanum juzecpzukii) and drought-tolerant (S. tuberosum subsp. andigena, Solanum spp.) landraces, showed similar positive responses.
• The optimized method outperformed previous protocols used by IPK and CIP genebanks.

Conclusions:

• The improved droplet PVS2 vitrification method is highly recommended for long-term potato germplasm conservation.
• This technique provides a secure and effective means to preserve the genetic diversity of potato collections.
• The protocol is suitable for a wide range of potato species and cultivars.