Inheritance of Leptine Production in Solanum chacoense

Abstract

Colorado Potato Beetle (Leptinotarsa decemlineata Say., CPB) is a destructive pest of the cultivated potato, Solanum tuberosum L. Certain glycoalkaloids in potato leaves are effective deterrents to this insect; however, in tubers these compounds can be toxic to humans. Leptines are foliar-specific glycoalkaloids produced by the related species, S. chacoense. These compounds have been shown to confer resistance to CPB. We are studying the inheritance of leptine production in segregating F1 and F2 populations derived from two S. chacoense accessions, 55-1 and 55-3, which are (respectively) high and low leptine producers. The F1 segregates 1:1 for high (>70% of total glycoalkaloids) and low (<20% of TGA) leptine content. Segregation data from the F1 and F2 populations suggest a twogene model for leptine production: a dominant repressor and a recessive inducer. Using two bulked DNA samples composed of highand low-leptine individuals from the F1 population, we are using various types of molecular markers (RAPDs, SSRs, DS-PCR, and AFLPs) to search for markers linked to leptine production. We have identified a RAPD band that appears to be closely associated with low leptine content and supports the two-gene model. The use of such a marker in a breeding program will facilitate the development of CPB resistant potato varieties.