Postharvest Biology and Technology of Fruits, Vegetables, and Flowers

POLYAMINES AND REGULATION OF RIPENING AND SENESCENCE 333
stresses. Although a number of chemicals, including polyamines, have been reported to
improve various desirable traits, more knowledge base is needed in order to apply this
technology to create plants precisely tailored to prevent fruit or produce loss normally incurred
during harvesting, handling, transportation, storage, and marketing. The focus of
this chapter has been to explore the role of PAs, particularly in influencing processes related
to postharvest shelf life of produce. Although much information has been generated, clear
understanding of the mechanisms of action of PAs is still in its infancy. Comprehensive
information regarding PA uptake, long-distance transport, and subcellular localization is
not complete. Is the role of PAs direct or manifested indirectly through their physical nature
and/or via other hormones? What are the signal transduction pathways downstream
of PA recognition, transport, and binding to functional components? The emerging technologies
should help substantially in addressing the role PAs play in postharvest biology
which can, in turn, be applied to increase both quality and shelf life of fresh produce. These
include genetic and biochemical approaches involving identification and characterization
of mutants altered in their response to PAs; using biosynthetic inhibitors and understanding
the mechanism of inhibition; recombinant DNA-based transgenic approaches coupled with
global gene expression analyses; metabolomics; and unraveling cross talks between PAs
and other plant growth hormones and regulators. These studies should ultimately lead to
rational design and strategic manipulation of biotechnological tools for enhancing valuable
postharvest traits in fruit and vegetable crops. Already steps are in place to lead us into the
inner core of PAs function, and depending on the nature of the focus, we may take one step
at a time or bypass several by strategizing logarithmic jumps. The dye is cast!
Acknowledgments
We like to thank Dr Anish Malladi for a critical review of this chapter. Polyamine research in
AKH and AKM laboratories were partly supported by a US-Israel BARD grant to AKH and
AKM (Grant No. IS-3441-03) and a grant from the U.S. Department of Agriculture, IFAFS
program (Award No. 741740) to AKH. Mention of trade names or commercial products
in this publication is solely for the purpose of providing specific information and does not
imply recommendation or endorsement by the U.S. Department of Agriculture.
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