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Variation for Tuber Greening in the Diploid Wild Potato Solanum Microdontum

John Bamberg, Moehninsi, Roy Navarre, Jana Suriano
American journal of potato research 2015 v.92 no.3 pp. 435-443
Solanum microdontum, Solanum tuberosum, clones, crossing, cultivars, diploidy, fluorescence, glycoalkaloids, greening disease, grocery stores, hybrids, inheritance (genetics), lighting, models, planting, postharvest diseases, postharvest physiology, potatoes, progeny, recessive genes, temperature, tubers, white light, Europe, North America
Greening of the tuber skin is an undesirable defect in fresh and processed potato. Tubers of 92 Solanum microdontum families represented by 12 individuals each were generated in the winter greenhouse in 2009–2010. These were evaluated in two trials of family bulks after 4 days of exposure to 200 ft candles of fluorescent white light at room temperature, similar to that observed in local grocery stores, and according to preliminary tests, able to turn some microdontum tubers very green. A qualitative score of green (G) or white (W) was assigned to each tuber. Tubers of about 10 % of families were scored as mostly W. In comparison, when 185 named Solanum tuberosum cultivars were illuminated in the same way, none from Europe or North America scored W. Two replicates of G and W individual tubers were selected from a variety of microdontum families and planted to create a new clonal generation of tubers. Those second generation daughter tubers showed a response to illumination which was consistent with that of the previous clonal generation. Finally, W and G clones were selected and mated. All GxG hybrids were uniformly G, but only three WxW crosses produced families that were nearly uniformly W. Thus some selections were shown to have consistent non-greening over trials spaced in time, over a clonal generation, and, when crossed together produced pure non-greening progeny. On the other hand, several very green selections similarly were consistently very green over time, clonal regeneration, and intermating. Tests of tuber tissue for glycoalkaloids showed that some illuminated clones neither green nor accumulate glycoalkaloids. These materials would make good models for further study of inheritance and physiology of the greening trait, and for breeding.