Jasmonate-induced Changes in Flavonoid Metabolism in Barley (Hordeum vulgare) Leaves
2002
Ishihara, Atsushi | OGURA, Yuki | TEBAYASHI, Shin-ichi | IWAMURA, Hajime
The effects of jasmonic acid (JA) on secondary metabolism in barley (Hordeum vulgare L.) were investigated. A reversed-phase HPLC analysis revealed that the amount of a particular compound increased in excised barley leaf segments that had been treated with JA. This compound was purified and identified as 6´´´-feruloylsaponarin (1) by spectroscopic analyses and alkaline hydrolysis. A related compound, 6´´´-sinapoylsaponarin (2), was also found to accumulate in excised leaves independently of the JA treatment. The accumulation of these compounds was accompanied by a decrease in the saponarin (3) content. [8,9-¹³C]p-Coumaric acid and [2,3,4,5,6-²H]L-phenylalanine were effectively incorporated into the hydroxycinnamoyl moieties in 1 and 2, while the degree of incorporation of the labeled precursors into the saponarin part was small. These findings indicate that the hydroxycinnamoyl moieties of 1 and 2 are synthesized de novo from phenylalanine via the phenylpropanoid pathway, and that the saponarin part is mainly provided by the constitutive pool of 3.
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