In an attempt to determine other physiological responses
to TRIA in addition to the elicitation of L(+)-adenosine, 20-
to 25-d-old tomato seedlings were sprayed with water or
TRIA, and after 1 min the plants were excised. Analysis of
the diffusate from the excised shoots, as determined by HPLC
and atomic absorption spectrophotometry, indicated large
concentration differences in organic compounds and inorganic
cations (unpublished data). The largest differences were
in the cation concentration of the exudate from the stump of
the excised tomato plant. Thus, the objective of this research
was to use this observation to further elucidate the mode of
action for the rapid responses of plants to TRIA and L(+)-
adenosine.
We present here evidence that foliar applications of both
of these compounds at nanomolar concentrations cause rapid
changes in soluble Ca2+, Mg2+, and K+ concentrations within
xylem exudates from the stumps of excised stems and leaves.