Submitted to: Plant Molecular Biology International Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: April 15, 2000
Publication Date: N/A
We have genetically engineered tomato fruits to accumulate polyamines, spermidine and spermine during ripening. We introduced yeast S-adenosylmethionine decarboxylase gene fused with the ripening-and ethylene-inducible E-8 promoter into tomato. Beneficial attributes of the transgenic fruit include longer vine and shelf life, robustness and a 3-fold increase in the lycopene content. Surprisingly, these fruit consistently produced more ethylene than the non-transformed or azygous fruit. This in vivo observation is in contrast to our previous in vitro studies where incubation of tomato fruit slices with mM concentrations of spermidine and spermine inhibited accumulation of ACC synthase transcripts. We are investigating the molecular basis for the in vivo stimulation of ethylene in the transgenic fruit. We tested whether the E-8 promoter sequences in the gene construct co-suppressed the endogenous E8 gene, which is an ethylene biosynthesis suppressor. We also analyzed accumulation of transcripts for ACC synthase, ACC oxidase, etr3, actin, E-8, and rDNA in transgenic and non-transgenic fruits. These data will be discussed in relation to engineering metabolic pathways for increasing phytonutrient content in vegetable crops.