ARS | Publication request: ASSESSMENT OF GENETIC HETEROGENEITY AND ALLELE VULNERABILITY AMONG BREEDING SYSTEMS IN POTATO

Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 3, 2004
Publication Date: August 15, 2004
Citation: Bamberg, J.B., Del Rio, A.H. 2004. Assessment of genetic heterogeneity and allele vulnerability among breeding systems in potato. American Journal of Potato Research. 81:377-383.

Interpretive Summary: Breeding better potatoes is key to increasing productivity and profitability of the crop. Diverse breeding stocks and wild relatives of potato found in potato genebanks are valuable tools for breeding better cultivars. To do an efficient job of providing a useful resource, genebanks need to know the best way to collect, classify, preserve and evaluate seed populations. One big factor that influences which approach is best, is how genetically uniform plants are within the seed populations. This research used DNA markers to measure genetic variation within populations of four species that are representative of different reproductive systems in potato, and found that it can vary widely. The conclusion is that if genebanks started taking these differences in genetic uniformity within populations into account, it could result in a more efficient job of managing the genetic resources, which would also ultimately result in a better product for breeders and other potato scientists.

Technical Abstract: Most potato populations at genebanks are collected, preserved and evaluated as botanical seed populations, so depending on their breeding system, populations can be potentially highly heterozygous and heterogeneous. However, some species are also selfers so potentially very homozygous, perhaps also homogeneous. This study investigated within-population genetic heterogeneity (GH) in 21 potato populations comprising four different breeding systems observed in Solanum species: S. jamesii (2n=2x=24, outcrosser), S. fendleri (2n=4x=48, disomic selfer) and S. verrucosum (2n=2x=24, selfer), and S. sucrense (2n=4x=48). Intrapopulation heterogeneity increases sampling error that can undermine consistency in seed regeneration in the genebank, evaluation results, germplasm collecting, and estimates of taxonomic relationships. Thus, knowledge of GH can predict the need to commit more resources for larger sample sizes or replication when populations of a given species is being regenerated, evaluated, collected and classified. RAPD markers were used to estimate heterogeneity among 18 to 24 individuals per population. Populations of S. verrucosum were quite homogeneous with an average GH of 3.6%. Similar low heterogeneity was detected among the 8 populations of S. fendleri for which (average GH=7.3%). In contrast, S. jamesii and S. sucrense had a much higher GH of 29.5% and 44.1%, respectively. These results demonstrate and quantify the great difference in intrapopulation heterogeneity among wild potato species.