|Jarret, Robert - Bob|
|ANGLIN, NOELLE - International Potato Center|
|ELLIS, DAVID - International Potato Center|
|VILLORDON, ARTHUR - Louisiana State University Agcenter|
|Jackson, Michael - Mike|
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 1/21/2019
Publication Date: 5/8/2019
Citation: Jarret, R.L., N. Anglin, D. Ellis, A. Villordon, P. Wadll and M. Jackson. 2019. Sweetpotato Genetic Resources: Today and Tomorrow. Burleigh Dodds, Cambridge, UK. ID 9781786764348. p. 1-52.
Interpretive Summary: In view of the importance of sweetpotato as a food source, various locations maintain and distribute diverse plant materials for use in breeding programs, scientific research and educational purposes. Large collections of sweetpotato clones are maintained in Lima, Peru at the International Potato Center and in the USA at the USDA genebank in Griffin, GA. These, and other locations, also maintain collections of species related to the sweetpotato. Most of the sweetpotato materials are maintained in tissue culture in a virus-tested state, in an aseptic environment. This enables/facilitates their international distribution. Research is being conducted to extend the period of time that the plants can be maintained in tissue culture before needing to be propagated. Brief discussions are provided on the current status of regulations effecting the international movement of sweetpotato and its related species and the use of modern DNA sequencing techniques for the detection of pathogens and for estimating genetic diversity within and between collections of sweetpotato. Information is also provided on recent studies evaluation both sweetpotato and its related species for traits that may be useful in crop improvement efforts and genetic studies that have provided information on the extent of diversity held in various genebank collections.
Technical Abstract: The sweetpotato (Ipomoea batatas (L.) Lam.) is the seventh most important food crop on a global scale. While China accounts for about 80% of global production, Nigeria, Uganda, Indonesia, and Tanzania are also large producers of sweetpotato. Sweetpotato production in the USA was approximately 1.34 x 109 kg in 2015. The genetic resources of sweetpotato include the cultivated hexaploid I. batatas, and many crop wild relatives (CWR). Indeed, the genus Ipomoea (Convolvulaceae) is quite large, containing 600-700 or more species. A recent survey indicates that more than 35,000 sweetpotato accessions are currently held in germplasm collections, globally. It is suggested that fewer than 10% of the currently recognized CWR (Ipomoea spp.) are represented in genebanks. Sweetpotato can be securely maintained in vitro for approximately one year (on average) at 20oC. However, storage time is genotype-dependent. Problems with bacterial or fungal contamination are not uncommon – and the health of in vitro collections must be closely monitored. Sweetpotato CWR are typically collected, propagated, maintained and distributed as botanical seed. Regeneration of sweetpotato CWR is resource intensive as many taxa are susceptible to attack by various diseases and insect pests. The international movement of sweetpotato germplasm is tightly regulated in order to prevent the unintentional dissemination of pathogens. In order to facilitate distribution and maintenance of I. batatas, next generation sequencing (NGS) approaches are being developed and employed for virus/pathogen detection and genotyping. Backup collections are utilized to ensure germplasm security – and these take various forms. No (global) core collection yet exists for the cultivated sweetpotato. However, more than 5,000 accessions have been characterized (by the International Potato Center (CIP) via SSR analysis) in an effort to fingerprint clones and to determine the boundaries of the primary genepool. These materials are currently being analyzed via DArTseq. Previous efforts to utilize molecular markers for germplasm characterization are discussed, as are recent studies that have evaluated sweetpotato genetic resources for agriculturally important traits. Genetic and genomic studies utilizing NGS approaches are providing insight into the sweetpotato genome (and the genomes of related species) to an extent not previously possible. Advances in technology continue to facilitate germplasm maintenance, evaluation and characterization/documentation efforts.