GENETIC ENGINEERING OF TOMATO FRUIT FOR SUSTAINED ACCUMULATION OF POLYAMINES DURING RIPENING TO STUDY THEIR PHYSIOLOGICAL ROLE(S)

Tomato fruits were engineered to accumulate polyamines, spermidine and spermine, during ripening by genetic introduction of S-adenosylmethionine decarboxylase (SAMdc) gene fused with the ripening-inducible promoter. The transgenic fruits were field tested over several years and the incorporated SAMdc gene was found to be stable. The higher levels of spermidine and spermine accumulated at the expense of their precursor putrescine and correlated with increased and sustained accumulation of the SAMdc gene transcripts, suggesting that the SAMdc expression enhances the flux of putrescine towards higher amines. Beneficial attributes of the transgenic fruit include longer vine and significant increase in the lycopene content.