Conservation of citrus germplasm: an international survey

Abstract

Citrus is one of the major fruit crops of the world, with production in subtropical and tropical areas of six continents. Citrus originated in south eastern Asia. Many of the forests in this region where natural populations of wild citrus likely occur have been developed for agriculture. Climate change threatens to further reduce the remaining habitat of wild citrus. The spread of modern citrus cultivars to these areas is displacing local selections and landraces. Therefore conservation of citrus germplasm is a priority, as recognized by development of a global citrus germplasm network in 1997. The International Treaty on Plant Genetic Resources for Food and Agriculture (ITPGRFA) has recognized Citrus as an Annex 1 crop, and an initial meeting in 2012 began work to establish a global conservation strategy for citrus. To characterize the current state of citrus germplasm collections, a survey of citrus genebanks was developed and distributed worldwide. Eleven germplasm collections responded to the survey. These collections vary in size, age, location in developed vs developing countries, and emphasis of the collection. Most collections are expanding, but they vary in rates of turnover of accessions, with some having high rates of loss. Most collections maintain germplasm primarily as field collections, but greenhouses, nurseries, and cryopreservation are used by some. Pest and disease problems are an economic problem for most collections and affect a wide range of accessions. Loss of accessions due to these problems affects only two collections. Relatively few collections distribute germplasm beyond the country in which they are located. Most collections report having inadequate funding, and need new trained staff to better manage citrus germplasm. We conclude that a global citrus germplasm network is needed with resources to provide stable funding to important but imperilled collections.