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Title: FOLIAR LEPTINE PRODUCTION IN SEGREGATING F1, INTER-F1, AND BACKCROSS FAMILIES OF SOLANUM CHACOENSE BITTER

Author
item Ronning, Catherine
item Sanford, Lind
item KOBAYASHI, RUTH - PAUL ECKE RANCH
item Kowalski, Stanley

Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: The Colorado potato beetle (CPB) is a highly destructive pest of the cultivated potato. Larval and adult forms feed on the leaves and can defoliate a plant in very short time. Compounds called glycoalkaloids, which are found naturally in the potato and in several related species, have been found to deter feeding of CPB. However, in high enough concentrations glycoalkaloids in potato tubers can be toxic to humans as well. Certain plants of Solanum chacoense, a wild species that is closely related to the cultivated potato, contain the leptine glycoalkaloids. The leptines are unique in that they are found only in the leaves, where they impart resistance to CPB, but not in tubers. This study was undertaken to determine the genetics of leptine production in S. chacoense. First generation results indicate that a single genetic factor controls leptine synthesis in this population; however, in subsequent generations at least one other genetic factor is involved; these factors may have complementary effects. If the gene for foliar leptine synthesis from S. chacoense can be transferred to the cultivated potato, natural CPB resistance may be transferred as well. Plant breeders will benefit from this research.

Technical Abstract: Levels of foliar leptine glycoalkaloids were measured in segregating families derived from S. chacoense sibs, 55-1 and 55-3, which are high and nil leptine producers (respectively), and from 8380-1, which produces high levels of leptine. A total of five F-1 families were produced from crosses between these genotypes. The F-1 crosses produced two leptine classes, high and low. Twenty-three families were derived from F-1 intercrosses and backcrosses of F-1 individuals. These families produced all high, all low, or both high and low leptine classes, depending upon type of cross. Three of the high x low F-1 families segregated 1:1 for high:low leptine, and progeny from the high x high cross were all high, indicating that a single recessive gene controls leptine production in this population. All of the low x high and high x high inter-F-1 and backcross families segregated as expected based on a single recessive gene model; however, five out of eight high x low and four out of six low x low families differed, suggesting the presence of additional factors affecting the inheritance and expression of leptine glycoalkaloids in this population of S. chacoense.