HYBRID BREAKDOWN IN THE F-1, BETWEEN SOLANUM-CHACOENSE AND SOLANUM-PHUREJA AND GENE-TRANSFER FOR LEPTINE BIOSYNTHESIS

F-1 hybrids between high leptine-producing clones (8380-1, PI 458310 a nd 55-1) of Solanum chacoense Bitt. and anther culture competent or an ther-derived clones of S.phureja Juz. & Buk, that did not produce lept ines were generally weak plants that grew slowly and died before flowe ring. Exceptional hybrids could be found that were capable of completi ng a life cycle, especially during the hot summer months in the greenh ouse. All F-1 hybrids produced leptines in the leaves but not the tube rs, albeit at lower levels than in the S. chacoense parent. Anther-der ived monoploids from the F-1 hybrids exhibited a range of leptine prod uction from none to levels approaching the S. chacoense parent. Backcr oss populations of an F-1 hybrid to the S. chacoense and S. phureja pa rents mere examined for leptine production. Backcross hybrids were gen erally much more vigorous than the F-1 hybrids. All of the S. chacoens e backcrosses produced leptines ranging from intermediate to high leve ls; four of the twelve S. phureja backcrosses exhibited low leptine le vels. A general dominance of leptine synthesis was therefore exhibited , although the nonleptine-producing parent affected the expression of leptines in the hybrids.