|Mehta, Roshni - FORMERLY OF VEGETABLE LAB|
|Handa, Avtar - PURDUE UNIVERSITY|
|Ali, Nasreen - UNIVERSITY OF MARYLAND|
Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 1999
Publication Date: N/A
Technical Abstract: Polyamines have been implicated in many physiological processes in plants, but their definite role in plant growth and development has not yet been elucidated. Polyamines stimulate anabolic metabolism of plants and seem to counteract the effect of pro-senescence hormones such as ethylene. To test whether tomato fruit metabolism could be modulated by an increase in the polyamines levels, we transformed tomato plants with a yeast S-adenosylmethionine decarboxylase (SAMdc) gene fused to the ripening and ethylene-responsive promoter, E-8. Ripe fruit from transgenic lines hemizygous and homozygous for the SAMdc-transgene accumulate polyamines, whereas the red fruit from segregating azygous lines have little, if any, spermidine and spermine. Fruits from two transgenic lines accumulate several-fold higher lycopene, and show delayed ripening and senescence than the control fruits. Surprisingly, with the accumulation of polyamines, the homozygous transgenic tomato fruits consistently produced more ethylene than the azygous line. We are now testing if this phenotype is a consequence of silencing of the endogenous E-8 gene. We are using these high polyamines-accumulating lines as models to study the role of polyamines in fruit ripening.