Submitted to: American Journal of Potato Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/14/2006
Publication Date: 6/1/2006
Citation: Bamberg, J.B. Crazy sepal: a new floral sepallata-like mutant in the wild potato Solanum microdontum bitter. American Journal of Potato Research. 83:433-435. Interpretive Summary: Potato is the most important US vegetable, and one of the best hopes for feeding an increasingly hungry world. Breeders try to keep producing better varieties to meet changing needs of the industry and preferences of consumers. A better understanding of basic potato reproduction and genetics helps breeders know how to most efficiently do that. We discovered a mutant in wild potato species that produces abnormal flowers. Instead of the usual bud leaves (sepals), petals, male and female organs, these mutant "flowers" have only repeating whorls of sepals, thus the name, "crazy sepal." This could be a useful tool for studying flower development and other practical features of reproduction and physiology. For example, would an absence of flowers provide more energy for the plant to invest in the tubers? Mutants are completely sterile, which may also have some practical applications for potato. Finally, since potato is a very close relative to other important food and ornamental crops for which the commercial part depends on flowering (tomatoes, pepper, eggplant, petunias), study of this "crazy sepal" mutant may have valuable application beyond potato.
Technical Abstract: The major economic impact of features of reproduction in Solanum and its close relatives make basic study of the genetics and physiology of flowering important in this genus. A qualitative floral-development mutant in the wild potato Solanum microdontum Bitter (PI 473166) was discovered that is ostensibly normal in all respects except that repeated (indeterminate) whorls of strap-like sepals replace petals, pistil and anthers, thus called "crazy sepal" = cs1. This mutant appears to be similar to sepallata mutants in Arabidopsis. Mutant clones vary in the development of sepals (ranging from small and light-colored to larger, dark and leaf-like) and the determinance of whorls. Crossing studies support single locus recessive inheritance. This mutant may be a useful tool for the study of floral genetics in Solanum, potential pleiotropic physiological effects on tuberization and other features of the potato crop. It would be a good marker for the study of rare genetic events since individuals reverting to flowering would be very easily detected among thousands of their mutant sibs. Transgene escape is of concern in potato, especially in Latin America where compatible wild species often grow in proximity to the crop. The absolute sterility of this mutant could be applied to this and similar practical breeding problems.