2013 Annual Report
1a.Objectives (from AD-416):
This project will combine physiological and genetic expertise and infrastructure to create a rational core collection and dataset for Solanum microdontum. This species, although wild, is remarkable for its broad expression for economically important tuber traits and ease of introgression into cultivars. The goal is to characterize for physiological tuber traits, and assess the patterns of phenotypes and genetics and the interaction of the two. This will allow for the more efficient management of this species in the genebank, and its deployment for cultivar breeding.
1b.Approach (from AD-416):
Grow all populations in the genebank to produce replicate sets of tubers. Assess for the physiological traits. Assess genetic variation patterns by AFLP and/or other markers. Perform statistical analysis of link between physiological traits and genetics clusters. Thus, identify and validate core collection and identify specific markers for germplasm screening. Preserve outstanding germplasm, facilitate use by ploidy manipulation, and advertise to germplasm users.
This project was renumbered from 3655-21000-051-03S to 3655-21000-057-01S. This is the final report, amendment in place to terminate project effective 6/30/2013. Solanum microdontum is a diploid potato species with features that make it a good model for research into management and use of germplasm in the genebank. Its taxonomic status is unambiguous and it is in the taxonomic series of wild species closest to cultivated forms. It is represented by about 100 populations in the genebank - not too many for comprehensive evaluation, yet not too few to make prioritization of the most valuable populations worthwhile. This species is also particularly rich in desirable traits, often exhibiting very broad segregation. We expanded work on use of deoxyribonucleic acid (DNA) markers to identify how genetic diversity is partitioned in this species as a model, with the goal of understanding how best to preserve and use diversity in the genebank. Nearly 1750 informative DNA markers were used to identify 45 of the 96 populations of S. microdontum that captured 98% of the genetic diversity in the whole species. These 45 populations also were found to encompass the most favorable state for 25 practical traits, including nutritional and quality components; disease, stress, and pest resistances. The entire set of microdontum populations was tested for resistance to foliar and tuber late blight, as well as tuber soft rot, finding sources of very strong resistance for all. The entire set of microdontum populations was tested for folate, identifying populations with relatively high levels of this important B vitamin. The entire set of microdontum populations was tested for resistance to tuber greening under light and some lines identified are virtually free of green color after four days under light. These were also tested for accumulation of the bitter compounds usually associated with greening. Some of the non-greening stocks also did not accumulate bitter compounds. Each microdontum population was hybridized with cultivated potato to facilitate evaluation for crop-relevant tuber traits. Some have already been identified as having high levels of anti-appetite (anti-obesity) compounds. As proposed in the objectives for this project, the genebank's populations of the wild potato species Solanum microdontum were evaluated for a variety of useful traits, a core collection was identified, and introgression into cultivated forms was accomplished.