Current perspectives on pollen cryopreservation in horticultural species

Cryopreserved pollen collections provide long-term security for wildflora, ornamentals, fruit and vegetable crops, medicinal herbs and endangered species. Technology has been developed for long-term cryopreservation of pollen in the form of nuclear genetic diversity (NGD) of mango, amla, pomegranate, jackfruit, guava, passion fruit, jamun, different species and cultivars of citrus, papaya (different species), grape, tomato, eggplant (Solanum gene pool), onion, capsicum, rose, gladiolus, gerbera, carnation and RET species of medicinal plants. Pollen collecting is usually done on a bright sunny day between 10-11 am. Pollen collections are subjected to viability indexing by germination in vitro by the hanging drop or cellophane techniques. Pollen samples are packed either in gelatin capsules or butter paper packets, sealed air tight in polyethylene aluminium laminated pouches and lowered into a canister of a cryoflask. The fertility of stored pollen is tested under field conditions through controlled pollination. The pollen cryobank is managed by periodic replenishment of the cryogen. With the recent advances in allied bio-scientific areas in which cryopreserved pollen could be used in general crosses, shuttle breeding maintenance of B line in male sterile based hybrid seed production. Security of male parent is also ensured in the cryobank. Pollen cryopreservation protocols developed for different horticultural species will be discussed in details.