Plant-herbivore interactions : The indigestibility of C4 bundle sheath cells by grasshoppers.

Plants with the C4 dicarboxylic acid pathway of photosynthetic CO2 fixation are generally nutritionally inferior to C3 (Calvin cycle) plants as foodstuff for herbivores. A possible contributing factor to this nutritional inferiority is the concentration, in C4 plants, of large quantities of nutritional material in very tough, thick-walled vascular bundle sheath cells which herbivores may not be able to break down. Experiments with 10 species of grass-hoppers from different areas in the United States revealed large numbers of unbroken bundle sheath cells, contents intact, in fecal pellets produced when the grasshoppers were fed C4 vegetation. We conclude that the material stored in C4 bundle sheath cells is at least partially unavailable to herbivores, and that this may contribute to the observed nutritional inferiority of C4 vegetation.