Induction of hairy roots and an inc

Induction of hairy roots and an increased production of plumbagin have been reported in P. zeylanica (Verma et al. 2002) and also in the same species (Gangopadhyay et al. 2008). Growth kinetics of hairy roots in P. zeylanica recorded 2.5 times higher amounts of plumbagin (fresh hairy roots) after 6 weeks of culture than that of untransformed control roots of the same age. Gangopadhyay et al. (2008) noticed an accumulation of 7.8 mg g–1 (0.78%) plumbagin from hairy roots of P. indica. In the present study, the root line R5 (without elicitation yielded 1.09 % DW plumbagin and was higher than that previously documented in P. indica (Gangopadhyay et al. 2008; Satheeshkumar et al. 2009).
Enhancement of metabolic flux and high biosynthesis of secondary metabolites through elicitation, abiotic as well as biotic, in plant cell culture systems has been emphasized (Ruiz-May et al. 2009; Shinde et al. 2009; Udomsuk et al. 2011). Komaraiah et al. (2003) obtained the highest yield (92.13 mg g–1) of plumbagin from cell suspension culture through immobilization and elicitation (using chitosan) with in situ product removal. But, the production of plumbagin by elicitation of cell cultures of P. rosea with chitosan alone and combination of immobilization and elicitation was 28.94 and 36.17 mg g–1, respectively. The potential of methyl jasmonate as a key signaling compound in the process of elicitation leading to the accumulation of several secondary metabolites from hairy roots has been documented: lignan from Linum tauricum (Ionkova 2009), terpene indole alkaloids from Catharanthus roseus (Ruiz-May et al. 2009), and alkamide from Echinacea spp. (Romero et al. 2009). In the present study, elicitation with MJ facilitated the highest yield of plumbagin. MJ is also exemplified as messengers in signal transduction chains of different pathways of biosynthesis and activation of secondary metabolites and enzymes, which partake in plant stress response (Pieterse et al. 2001). MJ is reported to induce the accumulation of terpene indole alkaloids by turning on the transcription of several genes involved in their biosynthesis (Lee-Parsons et al. 2004). As noted in Catharanthus roseus (Van der Fits and Memelink 2000), the high level accumulation of plumbagin may result from the induction of early MJ-responsive transcriptional regulators of the ORCAS’ transcription factors. Easy transport of exogenous MJ through the phloem as demonstrated in Nicotiana sylvestris (Zhang and Baldwin 1997) may also be one of the reasons for the efficacy of high plumbagin yield in the present study. Up-regulation of biosynthetic gene expression, oxidation, and conjugation of polyamines by MJ has also been reported (Biondi et al. 2001). Though acetylsalicylic acid was inferior to MJ in plumbagin production, 100 mM acetylsalicylic acid enabled the production of 3.5 times that of roots not subjected to elicitation. The efficacy of salicylic acid in secondary metabolite accumulation has been accomplished in Psoralea corylifolia (Shinde et al. 2009). Hairy root induction and elicitation with MJ in the present study proves an efficient strategy for the production of plumbagin compared to that of the previous reports. Transgenic plant regeneration occurred spontaneously on growth regulator-free media; however, high-frequency plant regeneration was accomplished through indirect organogenesis. Development of transformed plants from hairy roots in this species has been reported either spontaneously (Gangopadhyay et al. 2008) or by induction of plant growth regulators (Satheeskumar et al. 2009). In the present study, the transgenic plants regenerated both spontaneously and induced initially showed stunted shoots and wrinkled leaves as previously documented (Satheeskumar et al. 2009). Similar to this observation, transgenic plantlets with shortened internodes compared to wildtype plants has also been reported in Rehmannia glutinosa (Zhou et al. 2009). Satheeshkumar et al. (2009) has accomplished different morphovariants through plant regeneration from hairy roots of P. rosea. Though the present study also showed the formation of shoots with abnormal morphology, the shoots in the subsequent culture regained the normal growth status similar to the control plants in vitro. Accordingly, the shoots with difference in plant architecture upon transplantation grew normally after establishment. Further, very recently, Bettini et al. (2010) proved the effect of A. rhizogenes rolC gene on plant architecture (shortening of internodes) and auxin and abscisic acid levels by inserting rolC gene into tomato through A. tumefaciens. They noticed a significant reduction of indole-3-acetic acid levels in the shoot apical region of the transgenic clone rolC3 in comparison with both the control and the clone rolC1. Considering their conclusion and the resuming of normal growth of the plants in subsequent cultures (particularly on medium with BA and an auxin) as well as in field-established plants, the change in plant architecture by the insertion of rolC gene may be due to a temporary hormonal imbalance that interferes with the common factors modulating plant growth. In the present study, elicitation of hairy roots cultures of P. indica enabled optimized production of plumbagin. The regulatory steps in plumbagin biosynthetic pathway remain unraveled. MJ as an elicitor open the possibilities to study the biosynthetic pathway leading to plumbagin synthesis.

Kết quả (Việt) 1:

Cảm ứng của lông rễ và một gia tăng sản xuất của plumbagin đã được báo cáo trong P. zeylanica (Verma et al. 2002) và cũng có thể trong cùng một loài (Gangopadhyay et al 2008). Tăng trưởng động học của lông rễ trong P. zeylanica ghi 2,5 lần số tiền cao hơn của plumbagin (tươi lông rễ) sau 6 tuần văn hóa hơn kiểm soát untransformed rễ của cùng lứa tuổi. Gangopadhyay et al. (2008) nhận thấy một tích tụ của 7.8 mg g-1 (0,78%) plumbagin từ lông rễ của P. indica. Trong nghiên cứu hiện nay, gốc dòng R5 (mà không có elicitation mang lại 1,09% DW plumbagin và cao hơn so với trước đây tài liệu trong P. indica (Gangopadhyay et al. 2008; Satheeshkumar et al. năm 2009).Enhancement of metabolic flux and high biosynthesis of secondary metabolites through elicitation, abiotic as well as biotic, in plant cell culture systems has been emphasized (Ruiz-May et al. 2009; Shinde et al. 2009; Udomsuk et al. 2011). Komaraiah et al. (2003) obtained the highest yield (92.13 mg g–1) of plumbagin from cell suspension culture through immobilization and elicitation (using chitosan) with in situ product removal. But, the production of plumbagin by elicitation of cell cultures of P. rosea with chitosan alone and combination of immobilization and elicitation was 28.94 and 36.17 mg g–1, respectively. The potential of methyl jasmonate as a key signaling compound in the process of elicitation leading to the accumulation of several secondary metabolites from hairy roots has been documented: lignan from Linum tauricum (Ionkova 2009), terpene indole alkaloids from Catharanthus roseus (Ruiz-May et al. 2009), and alkamide from Echinacea spp. (Romero et al. 2009). In the present study, elicitation with MJ facilitated the highest yield of plumbagin. MJ is also exemplified as messengers in signal transduction chains of different pathways of biosynthesis and activation of secondary metabolites and enzymes, which partake in plant stress response (Pieterse et al. 2001). MJ is reported to induce the accumulation of terpene indole alkaloids by turning on the transcription of several genes involved in their biosynthesis (Lee-Parsons et al. 2004). As noted in Catharanthus roseus (Van der Fits and Memelink 2000), the high level accumulation of plumbagin may result from the induction of early MJ-responsive transcriptional regulators of the ORCAS’ transcription factors. Easy transport of exogenous MJ through the phloem as demonstrated in Nicotiana sylvestris (Zhang and Baldwin 1997) may also be one of the reasons for the efficacy of high plumbagin yield in the present study. Up-regulation of biosynthetic gene expression, oxidation, and conjugation of polyamines by MJ has also been reported (Biondi et al. 2001). Though acetylsalicylic acid was inferior to MJ in plumbagin production, 100 mM acetylsalicylic acid enabled the production of 3.5 times that of roots not subjected to elicitation. The efficacy of salicylic acid in secondary metabolite accumulation has been accomplished in Psoralea corylifolia (Shinde et al. 2009). Hairy root induction and elicitation with MJ in the present study proves an efficient strategy for the production of plumbagin compared to that of the previous reports. Transgenic plant regeneration occurred spontaneously on growth regulator-free media; however, high-frequency plant regeneration was accomplished through indirect organogenesis. Development of transformed plants from hairy roots in this species has been reported either spontaneously (Gangopadhyay et al. 2008) or by induction of plant growth regulators (Satheeskumar et al. 2009). In the present study, the transgenic plants regenerated both spontaneously and induced initially showed stunted shoots and wrinkled leaves as previously documented (Satheeskumar et al. 2009). Similar to this observation, transgenic plantlets with shortened internodes compared to wildtype plants has also been reported in Rehmannia glutinosa (Zhou et al. 2009). Satheeshkumar et al. (2009) has accomplished different morphovariants through plant regeneration from hairy roots of P. rosea. Though the present study also showed the formation of shoots with abnormal morphology, the shoots in the subsequent culture regained the normal growth status similar to the control plants in vitro. Accordingly, the shoots with difference in plant architecture upon transplantation grew normally after establishment. Further, very recently, Bettini et al. (2010) proved the effect of A. rhizogenes rolC gene on plant architecture (shortening of internodes) and auxin and abscisic acid levels by inserting rolC gene into tomato through A. tumefaciens. They noticed a significant reduction of indole-3-acetic acid levels in the shoot apical region of the transgenic clone rolC3 in comparison with both the control and the clone rolC1. Considering their conclusion and the resuming of normal growth of the plants in subsequent cultures (particularly on medium with BA and an auxin) as well as in field-established plants, the change in plant architecture by the insertion of rolC gene may be due to a temporary hormonal imbalance that interferes with the common factors modulating plant growth. In the present study, elicitation of hairy roots cultures of P. indica enabled optimized production of plumbagin. The regulatory steps in plumbagin biosynthetic pathway remain unraveled. MJ as an elicitor open the possibilities to study the biosynthetic pathway leading to plumbagin synthesis.