|Del Rio, A - UNIV OF WISCONSIN|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 30, 2003
Publication Date: February 1, 2004
Citation: Del Rio, A., Bamberg, J.B. 2004. Geographical parameters and proximity to related species predict genetic variation in the inbred potato species solanum verrucosum schlechtd. Crop Science. 44:1170-1177. Interpretive Summary: A major goal of crop genebank managers is to maximize the breadth of genetics they keep. It would help to find patterns of variation in the geography or habitat (where samples grow in the wild) that predict variation in genetics of the populations. Previous studies using three wild potato species failed to find any such associations. However, this study, using a fourth species, Solanum verrucosum from Mexico, revealed that populations that were most northwest were most genetically unique. The proximity to certain other potato species also predicted the genetic novelty of S. verrucosum populations. This information will help genebank managers prioritize future collections so that the genetic diversity in the genebank is maximized. Naturally, maximizing genetic diversity in the genebank means that there will be more traits available for breeders to use to make future varieties more productive, disease resistant, tasty and nutritious.
Technical Abstract: A major goal of crop genebank managers is to maximize the genetic diversity they keep. Finding ecological or geographic parameters that are associated with genetic variation would guide prioritization of populations for collection and maintenance. Previous studies among wild populations of S. fendleri (a disomic polyploid selfer), S. jamesii (a diploid outcrosser) and S. sucrense (a polysomic polyploid outcrosser) revealed no significant associations between genetic and ecogeographic variation. Even physical separation did not predict genetic differences. These species represent three of the breeding systems found among Solanum species. These previous studies are expanded here by investigating the relationship of genetics and geographic parameters for a fourth type of breeding system: a diploid inbred, modeled by wild S. verrucosum (2n=2x=24) from Mexico. The objective was to assess whether genetic differences between populations are predicted by differences in geographic parameters at the natural site of origin. Proximity of the S. verrucosum populations to other Mexican wild potato species populations (some known to be sympatric with S. verrucosum) was also analyzed. A total of 27 S. verrucosum populations were studied using RAPD markers to estimate genetic differences between pairs of populations. A total of 352 pairwise comparisons based on 152 RAPD markers showed that the average genetic distance (GD) of all pairs of populations was 12.8 % (ranging from 0% to 29.3%). The greatest correlations with GD were: latitude (70%), longitude (51%), physical separation (47%), altitude (-27%); proximity to S. demissum (59%), S. hjertingii (80%), and S. hougasii (-56%).