The Three Responses of Plant Tissue to Wounding
We are all aware that fresh-cut produce is alive, with all its accompanying attributes, but we often fail to consider what happens to the injured tissue as it responds to being wounded. The response to wounding can be physical (dependent on the current physical make-up of the tissue), biochemical (dependent on the existing chemicals within the tissue), and/or physiological (dependent on the ability of the wounded and adjacent tissue to respond physiologically). Plant tissues have evolved an impressive, but very limited, number of physiological responses to naturally occurring injuries. These responses can be desirable (e.g., wound healing of harvested root crops, production of pharmaceutical compounds) or undesirable (e.g., lignification of vascular tissue, browning of cut surfaces). While most injuries incurred during fresh-cut preparation mimic naturally occurring injuries (e.g., cuts and abrasions), a few are so extensive (e.g., producing ‘baby’ carrots, cubing melons) that they can overwhelm the tissue’s ability to deal with them properly and can elicit unexpected responses. The physiological response to these injuries may be mediated through a number of intermediates (e.g., wound signals, plant-growth regulators like ethylene). Understanding the limitations of natural responses and how to modulate them can be used to produce a more desirable fresh-cut product.