Indian cryogenebank conserving diverse plant genetic resources for the last three decades: Achievements and way forward.

Ex situ conservation of plant genetic resources (PGR) plays a crucial role in sustainable growth and development, as highlighted by the Global Strategy for Plant Conservation (GSPC). Seed genebanks, a key component of ex situ conservation, have been instrumental in preserving plant diversity. However, challenges arise with the conservation of non-orthodox (recalcitrant and intermediate) seeds and vegetative tissues, which are not amenable to storage in traditional genebanks at temperatures of -20 °C. Cryopreservation, the storage of biological materials at ultra-low temperatures in liquid nitrogen, has emerged as a viable solution for conserving such non-orthodox seeds, pollen, and dormant buds. This review presents insights into the National Cryogenebank Facility at ICAR-NBPGR, India, a pioneer in developing cryopreservation techniques and cryobanking of PGR. Established in 1987, the facility focuses on conserving difficult-to-conserve species of various agri-horticultural crops, including recalcitrant and intermediate species. With a capacity to hold a quarter of a million samples, the facility employs species-specific protocols to conserve rare, threatened, and endangered plant species, wild and weedy crop relatives, and genetic stocks. Over the past 3 decades, cryopreservation protocols have been developed at this facility using a diverse range of explants, including seeds, excised embryos, embryonic axes, pollen grains, and dormant buds. Successful cryopreservation protocols have been developed for temperate and tropical plant species important for horticultural, plantation, agro-forestry, and industrial use. Priority is given to conserving indigenous crop species and capturing the genetic diversity of indigenous tropical and temperate major and minor fruits. Additionally, the facility has successfully conserved pollen grains and dormant buds of tropical and temperate fruit crops, ensuring their viability and survival over extended periods of cryostorage. Furthermore, the cryobank regularly retests cryostored germplasm to assess viability and regrowth, with promising results indicating retention of seed viability even after 25-30 years of cryostorage. This highlights the potential of cryobanking as a long-term solution for conserving plant genetic resources. The National Cryogenebank Facility at ICAR-NBPGR exemplifies advancements in cryopreservation techniques applicable to plant genetic resource conservation, contributing significantly to national, regional and global efforts towards ex situ conservation of difficult-to-store plant species and overall sustainable agricultural development.