RESUMEN
In the present study, the effects of the metabolite elicitors chitosan, methyl jasmonate (MeJA) and salicylic acid (SA) as well as the hairy root transformation were tested for silymarin and phenolic compound accumulation in in vitro cultures of Milk thistle. For callus induction, leaf explants were cultured on MS medium supplemented with 5 mg/l NAA + 2 mg/l Kin + 0.1 mg/l GA3. Chitosan, SA and MeJA were added separately in three concentrations 200, 400 and 800 mg/l; 10, 20 and 40 mg/l; 20, 40 and 80 mg/l, respectively, to hormone free B5 medium. Alternatively, cotyledons of 12 day old seedlings were transformed with Agrobacterium rhizogenes A4 strain. Overall, increasing the concentrations of the three elicitors dramatically increased the total silymarin content. Remarkably, the elicitors mainly enhanced the accumulation of silybine A&B that were not detected in un-treated callus culture (control). In addition, the hairy root culture triggered the accumulation of silybine A&B, and silydianin, which was not detected in the non-transgenic roots. The hairy root culture was superior in production of the phenolic compounds in comparison to the control and elicitor treatments. The hairy root cultures showed also higher antioxidant capacities than non-transformed cultures and/or chemically elicited-callus cultures. Thus hairy root provide instrumental in enhancing the production of economically valuable metabolite.
RESUMEN
This study was carried out to investigate the effect of mannitol, sorbitol and sucrose as osmotic agents on in vitro conservation of embryogenic cultures of date palm (Phoenix dactylifera, L.) Bartamoda and Sakkoty cultivars. Embryogenic cultures was obtained using MS medium supplemented with 10 mg/l 2,4-dichlorophenoxy acetic acid (2,4-D) and 3 mg/l isopentenyl adenine (2iP). Among the three types of osmotic substances used for slow growth conservation, sucrose at all concentrations gave the highest percentage of survival with Sakkoty cultivar. However, addition of 40 g/l or 60 g/l mannitol and 20 g/l sorbitol showed the highest percentage of survival percentage with Bartamoda cultivar. The different sucrose concentrations caused higher numbers of germinated embryos of the two cultivars compared with mannitol or sorbitol. Also, the number of germinated embryos was increased with increasing the storage periods till the ninth month. Genetic stability was determined using random amplified polymorphic DNA (RAPD) analysis. There were no clear genetic differences between the two osmotic agents used for preservation. The preserved cultures of Sakkoty cultivar gave the high percent of similarity while Bartamoda cultivar gave low percent of similarity. From the obtained results we can recommend using 40 g/l mannitol or 20 g/l sorbitol for in vitro preservation of Bartamoda cultivar of date palm and 20 g/l of sucrose for Sakkoty cultivar.