Hybrid breakdown in the F1 between Solanum chacoense and S. phureja and gene transfer for leptine biosynthesis

Abstract

F1 hybrids between high leptine-producing clones (8380-1, P1458310 and 55-1) of Solanum chacoense Bitt. and anther culture competent or anther-derived clones of S. phureja Juz. and Buk. that did not produce leptines were generally weak plants that grew slowly and died before flowering. Exceptional hybrids could be found that were capable of completing a life cycle, especially during the hot summer months in the greenhouse. All F1 hybrids produced leptines in the leaves but not the tubers, albeit at lower levels than in the S. chacoense parent. Anther-derived monoploids from the F1 hybrids exhibited a range of leptine production from none to levels approaching the S. chacoense parent. Backcross populations of an F1 hybrid to the S. chacoense and S. phureja parents were examined for leptine production. Backcross hybrids were generally much more vigorous than the F1 hybrids. All of the S. chacoense backcrosses produced leptines ranging from intermediate to high levels; four of the twelve S. phureja backcrosses exhibited low leptine levels. A general dominance of leptine synthesis was therefore exhibited, although the nonleptine-producing parent affected the expression of leptines in the hybrids.