effects of methyl jasmonate and chitosanon shoot and callus growth of iranian hypericum perforatum l. in vitro cultures

The present study was investigated the effects of two elicitors methyl jasmonate (0, 125, 250 and 500 µm) and chitosan (0, 50, 150 and 250 mg l^-1) on shoot and callus growth of iranian hypericum perforatum l. in vitro cultures in separate experiments. the experiment was done in the base of completely randomized design with five replications and five explants in each replication. methyl jasmonate significantly reduced the regeneration of cultured shoots and developed shoots necrosis as well as the growth of treated calluswith methyl jasmonate was ceased. in spite of methyl jasmonate, chitosanwas more effective in stimulating the growth of cultured explants. chitosan significantly increase the regeneration of h. perforatum shoots and the highest regenerated shoots number (9.29 shoots per explant) and shoot weight (1.82 g) were obtained in 250 mg l^-1chitosan. the growth of callus in response to chitosan was higher than control treatment and the treated calli with 250 mg l^-1 chitosan showed the highest diameter and weight. the essential oil content and chemical compositions of in vitro proliferated iranian h. perforatum shoots were also investigated. the essential oil content was 0.02% (w w^-1). the characterization of essential oil by gc and gc/ms analyses, allowed the identification of 35 volatile constituents, accounting for 97.01% of the total oil composition and sesquiterpenes (51.72%) represented by γ–gurjunene (22.34%) were the main compounds.