R. Kramell et al., OCCURRENCE AND IDENTIFICATION OF JASMONIC ACID AND ITS AMINO-ACID CONJUGATES INDUCED BY OSMOTIC-STRESS IN BARLEY LEAF TISSUE, Journal of plant growth regulation, 14(1), 1995, pp. 29-36
The effect of osmotically active substances on the alteration of endog
enous jasmonates was studied in barley (Hordeum vulgare L. cv. Salome)
leaf tissue. Leaf segments were subjected to solutions of D-sorbitol,
D-mannitol, polyethylene glycol 6000, sodium chloride, or water as a
control. Alterations of endogenous jasmonates were monitored qualitati
vely and quantitatively using immunoassays. The structures of jasmonat
es isolated were determined on the basis of authentic substances by ca
pillary gas chromatography-mass spectrometry. The stereochemistry of t
he conjugates was confirmed by high performance liquid chromatography
with diastereoisomeric references. In barley leaves,jasmonic acid and
its amino acid conjugates, for example, with valine, leucine, and isol
eucine, are naturally occurring jasmonates. In untreated leaf segments
, only low levels of these native jasmonates were found. After treatme
nt of the leaf tissues with sorbitol, mannitol, as well as with polyet
hylene glycol, an increase of both jasmonic acid and its conjugates co
uld be observed, depending on the stress conditions used. In contrast,
salt stress was without any stimulating effect on the levels of endog
enous jasmonates. From barley leaf segments exposed to sorbitol (1 M)
for 24 h, jasmonic acid was identified as the major accumulating compo
und. Jasmonic acid-amino acid conjugates increased likewise upon stres
s treatment.