Which method of storage is used for preserving pollen grains?

Liquid nitrogen at -196°C

Storing pollen grains in liquid nitrogen is done to preserve their viability for an extended period. Liquid nitrogen has an extremely low temperature of -196°C, which significantly slows down biological processes and effectively suspends the metabolic activities of the pollen grains. This preservation method is commonly used in pollen banks, similar to seed banks, to ensure the long-term storage and availability of diverse pollen resources for plant breeding and conservation programs.

By immersing the pollen grains in liquid nitrogen, they are kept in a state of suspended animation, preventing them from undergoing deterioration and loss of viability. The ultra-low temperature helps to maintain the integrity of the pollen grains, preventing enzymatic breakdown and metabolic degradation that would occur under normal conditions.

When the time comes to use the stored pollen, it can be thawed and rehydrated, and its viability can be assessed through various techniques such as germination tests or viability staining. The extended viability of stored pollen grains allows for their utilization in controlled pollination experiments, hybridization programs, and cross-breeding efforts, even years after their initial collection.

It's important to note that storing pollen grains in liquid nitrogen does not induce mutations or enhance their fragrance. The primary purpose is to maintain their viability and genetic integrity, ensuring the availability of diverse pollen resources for future plant breeding activities.