Individual and combined effects of the rolA, B, and C genes on anthraquinone production in Rubia cordifolia transformed calli

Abstract

It is known that the rolA, rolB, and rolC genes of Agrobacterium rhizogenes T-DNA affect processes of plant development and activate the synthesis of secondary metabolites in transformed plant cells. Although a synergistic activity of the rol genes on root formation is well-documented, little is known about their individual and combined action on secondary metabolism. In the present investigation, we provide evidence indicating that individual rolA, rolB, and rolC genes are capable of increasing biosynthesis of anthraquinones (AQs) in transformed calli of Rubia cordifolia. The stimulatory effect was due to the increased transcription of a key gene of AQ biosynthesis, the isochorismate synthase (ICS) gene. The strongest AQ-stimulating activity was shown for an R. cordifolia culture expressing rolB at high levels, where rolB ensured a 15-fold increase of AQ accumulation compared with the control, non-transformed calli. A tyrosine phosphatase inhibitor abolished the rolB-induced increase of AQ production, thus indicating the involvement of tyrosine (de)phosphorylation in the rolB-mediated AQ stimulation. The rolA- and rolC-expressing cultures produced 2.8- and 4.3-fold higher levels of AQs, respectively, when compared with the control calli. However, the effect of rolA, rolB, and rolC on AQ biosynthesis was not synergistic because rolA and rolC apparently attenuated the stimulatory effect of rolB on AQ biosynthesis. Therefore, the rol-gene-mediated signals that promote root formation and those which activate biosynthesis of secondary metabolites seem to have a point of divergence.

Can plant oncogenes inhibit programmed cell death? The rolB oncogene reduces apoptosis-like symptoms in transformed plant cells

“…5 The strength of expression of rolB in the RBM culture is similar to the expression of rolB from its own 5' promoter. 7 In the RBH culture, rolB has a 2.5-fold higher expression level than in the RBM culture. Thus, RBH represents a culture with the maximum possible rolB transcript abundance; increasing the expression of rolB in R. cordifolia cells to higher levels induces cell death.…”

“…Thus, RBH represents a culture with the maximum possible rolB transcript abundance; increasing the expression of rolB in R. cordifolia cells to higher levels induces cell death. 5,7 The stability of the rolB gene expression was controlled during this …”

Induction of anthraquinone biosynthesis in Rubia cordifolia cells by heterologous expression of a calcium‐dependent protein kinase gene

“…R. cordifolia calli, which produce colored phytoalexins (anthraquinones), represent a well-known model for studies of effects of transgenes on secondary metabolism Shkryl et al, 2008).…”

“…The RcICS gene was previously isolated from R. cordifolia calli and its expression was shown to be tightly connected with AQ accumulation Shkryl et al, 2008). To estimate the effect of heterologous CDPK expression on the RcICS gene expression, we performed quantitative real-time RT-PCR analysis.…”

Study on construction of transformation vectors carrying contructs of rol genes highly effective in plant hairy roots induction

“…Kết quả này phù hợp với những nghiên cứu trong lĩnh vực công nghệ hóa sinh gần ñây về các root locus nằm trên vùng TL-DNA của plasmid Ri. Theo ñó, hoạt ñộng của gen rolB ñược chứng minh là giữ vai trò quan trọng nhất trong sự hình thành rễ tơ ở thực vật, ñồng thời thúc ñẩy mạnh mẽ quá trình tổng hợp các hợp chất thứ cấp [23]. Tuy nhiên, sự biểu hiện quá mức của gen này trong các mô chuyển gen có thể gây ức chế sự phát triển của tế bào [8].…”