Novel chemically synthesized hydroxyl-containing jasmonates as powerful inducing signals for plant secondary metabolism

Novel hydroxyl-containing jasmonate derivatives were chemically synthesized and evaluated by bioassay as potential elicitors for stimulating the biosynthesis of plant secondary metabolites. A suspension culture of Taxus chinensis, which produces a bioactive taxoid, taxuyunnanine C (Tc), was taken as a model plant cell system. Experiments on the timing of addition of jasmonates and dose response indicated that day 7 and 100 μM was the optimal elicitation time and concentration, respectively, for both cell growth and Tc accumulation. Tc accumulation was increased more in the presence of novel hydroxylcontaining jasmonates compared to that with methyljasmonate (MJA) addition. For example, addition of 100 μM 2,3-dihydroxypropyl jasmonate on day 7 led to a very high Tc content of 47.2 ± 0.5 mg/g (at day 21), whereas the Tc content was 29.2 ± 0.6 mg/g (on the same day) with addition of 100 μM MJA. Quantitative structure-activity analysis of various jasmonates suggests that the optimal lipophilicity and the number of hydroxyl groups may be two important factors affecting their elicitation activity. In addition, the jasmonate elicitors were found to induce plant defense responses, including oxidative burst and activation of L-phenylalanine ammonia lyase (PAL). Interestingly, a higher level of H₂O₂ production and PAL activity was detected with elicitation by the synthesized jasmonates compared with that by MJA, which corresponded well to the superior stimulating activity in the former. This work indicates that the newly synthesized hydroxylcontaining jasmonates can act as powerful inducing signals for secondary metabolite biosynthesis in plant cell cultures.