Citrus

The genus Citrus L., the sole source of the Citrus fruits of commerce, belongs to the orange subfamily Aurantioideae of the family Rutaceae and is cultivated in the tropical, subtropical, and Mediterranean climate of the world. Citrus fruits are well known for their dietary, nutritional, medicinal, and cosmetic properties. The word “citrus” probably originated from the Greek word Kedros originally means “cedrus.” Greek word Kedros is Latinized to “Cedrus” which later on was changed to “citrus.” The taxonomy of Citrus L. is very complex and still under investigation. Currently two different classification systems of Citrus are commonly accepted for the Citrus taxonomy, the Swingle and Tanaka’s system. Hodgson revised the taxonomic system of Swingle and Tanaka and suggested the system having 36 species. Despite rich diversity present in citrus, erosion of genetic resources of citrus is taking place due to various biotic and abiotic factors resulting in the loss of gene pools from nature. Considering the importance of citrus genetic resources for the present use and future needs, efforts for genetic resources management, namely, collection, characterization, conservation, and utilization, should be undertaken immediately as a mission mode program. Collection of germplasm of diverse species and local cultivars from various natural habitats/sites, farmers’ orchards, and field genebanks need to be undertaken and characterized. Ex situ and in situ conservation of rare and endangered species should urgently be undertaken for dynamic conservation and sustainable use of genetic resources of all available citrus germplasm. Cryopreservation and in vitro storage of seeds can also be attempted to safeguard the germplasm. Bioprospecting and value addition of nonedible species for confirmation of medicinal and nutritional traits would aid in their utilization. The use of modern biotechnological tools would further enhance the possibilities of utilizing rare genes to mitigate the challenges of climate change.