Labavitch Lab

Cell wall metabolism and plant-insect interactions.
Many herbivorous insects, both larval and adult forms, use CWDPs to feed on plant tissues.  The lygus bug (Lygus hesperus), an insect that feeds on and damages many important crop plants (cotton, alfalfa, beans, tomatoes et al.), produces several salivary PGs that are extruded onto plant tissues during feeding.  This salivary PG is responsible for the flower damage that is caused when the lygus bug feeds on alfalfa florets and cotton flowers (Shackel et al., 2005).  Isolation of salivary glands from over 1,000 insects was followed up by a protein purification effort that identified several distinct lygus bug salivary PGs (Celorio-Mancera et al., 2009).  N-terminal sequencing of some of these PGs supported the cloning of two L. hesperus PGs and a subsequent, focused proteomic analysis led to the demonstration that these PGs were secreted into the insect's diet during feeding (Celorio-Mancera et al., 2008).  Additional work with these insect PGs showed that they, too, were inhibited by the pear PGIP.  Therefore, another research theme in our program is aimed at learning whether a "PGIP strategy" could be used to mitigate the plant damage caused by the feeding of insects with salivary PGs.

 
When the lygus bug feeds on alfalfa florets like those in the left-hand photo, they fail to develop and die (red asterisk, right). When florets like those on the left are injected with PG from the lygus bug’s saliva, those florets also wither and die, suggesting that it is the salivary PG that causes the feeding damage caused by the lygus bug.  Plant PG-inhibiting proteins (PGIPs) can block lygus bug PG action.  Can PGIPs protect crop plants from the lygus bug? (Shackel et al., 2005)

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