trichoderma strains- silybum marianum hairy root cultures interactions

background and objectives: silymarin is a unique flavonoid complex with documented hepatoprotective properties. silybum  marianum hairy root culture as a source for producing silymarin has been an important strategy for study the cell signaling pathway. in the present investigation trichoderma strains- silybum marianum hairy root cultures interactions have been studied. methods: the effects of two trichoderma strains (khb and g46-7) (0, 0.5, 1, 2 and 4 mg/ 50 ml culture) in 6 different exposure times (0, 24, 48, 72, 96 and 120 h) have been investigated on flavonolignans production. the flavonolignans were analyzed by high performance liquid chromatography method. cell signaling pathway was evaluated by determination of h2o2 content, peroxidase and ascorbate peroxidase activities. results:the elicitation effects of two trichoderma strains (khb and g46-7) were examined on flavonolignans accumulation and the activation of cell defense system in s. marianum hairy root cultures. the results indicated that the highest silymarin accumulation (0.45 and 0.33 mg/g dw) was obtained in media elicited with 0.5 mg/50 ml cultures of t. harzianum strains (khb and g46-3, respectively) after 120 h. feeding time experiments indicated that a significant higher content of silymarin production was achieved after 120 and 72 h in media treated with 0.5 mg/50 ml cultures of khb and g46-3, respectively. our results showed that s. marianum treated by khb strain, increased taxifolin, silychristin, isosilybin and silydianin productions significantly. the h2o2 content in the control hairy root cultures remained lower than the treated cultures. there was significant enhancement in both peroxidase and ascorbate peroxidase activities in treated hairy roots reaching a peak after 72 h. conclusion: these findings suggested that some trichoderma strains are positive elicitors for promoting silymarin accumulation in s. marianum hairy root cultures. the results also suggested the presence of h2o2 and oxidative burst induced by t. harzianum as a signaling pathway.