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Figure 10 | BMC Plant Biology

Figure 10

From: The ORCA2 transcription factor plays a key role in regulation of the terpenoid indole alkaloid pathway

Figure 10

Model for the role of ORCA2 in regulation of TIA biosynthesis. A possible model for ORCA2 regulation of TIA biosynthesis is presented. The signal triggered by binding of elicitors activates the jasmonic acid signaling pathway, which then activates ORCA2 and ORCA3. ORCA2 and ORCA3, together with other transcriptional regulators (not shown), induce expression of specific TIA biosynthetic genes. ORCA2 also, directly or indirectly, up-regulates its own expression as well as expression of ORCA3. ORCA2 (this work) and ORCA3 [27] also, directly or indirectly, induce expression of the ZCT1, ZCT2 and ZCT3 TIA transcriptional repressor genes. As the activities of ZCT1, ZCT2 and ZCT3 increase they begin to repress expression of particular TIA biosynthetic genes. As a result, increased expression of ORCA2 or ORCA3 tends to cause increases in TIA biosynthetic gene transcript levels and TIA metabolite levels that are both transient and limited in magnitude.

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