Peroxidase and catalase activities are involved in direct adventitious shoot formation induced by thidiazuron in eastern white pine ( Pinus strobus L.) zygotic embryos

We reported establishment of an efficient plant regeneration procedure through direct adventitious shoot (DAS) formation from cotyledons and hypocotyls of eastern white pine ( Pinus strobus L.) mature embryos in this investigation. Multiple DASs were initiated from cotyledons of embryos on PS medium containing N 6-benzyladenine (BA), thidiazuron (TDZ), or kinetin (KIN). Among different concentrations of casein enzymatic hydrosylate (CH) and glutamine used in this study, 500 mg l −1 CH or 600 mg l −1 glutamine induced the highest frequency of DAS formation. Rooting of regenerated shoots was obtained on PS medium supplemented with 0.01–0.1 μM indole-3-acetic acid (IAA) with the highest frequency on medium containing 0.01 μM IAA. No DASs were obtained on medium without TDZ. Measurement of peroxidase (POD) and catalase (CAT) activity during direct shoot induction and differentiation demonstrated that the lowest POD activity appeared in the 5–6th week of culture and lowest CAT activity occurred in the 7–8th week of culture on medium with TDZ. No such a change in POD and CAT activities was observed on medium without TDZ. These results demonstrated that POD and CAT activities were involved in DAS formation induced by TDZ in eastern white pine.