**Effect of** *Aspergillus flavus* **Fungal Elicitor on the Production of Terpenoid Indole Alkaloids in** *Catharanthus roseus* **Cambial Meristematic Cells**

**Chuxin Liang 1,†, Chang Chen 2,†, Pengfei Zhou 3,†, Lv Xu 1, Jianhua Zhu 1,2,\*, Jincai Liang 2, Jiachen Zi <sup>2</sup> and Rongmin Yu 1,2,\***


Received: 22 October 2018; Accepted: 10 December 2018; Published: 11 December 2018

**Abstract:** This study reported the inducing effect of *Aspergillus flavus* fungal elicitor on biosynthesis of terpenoid indole alkaloids (TIAs) in *Catharanthus roseus* cambial meristematic cells (CMCs) and its inducing mechanism. According to the results determined by HPLC and HPLC-MS/MS, the optimal condition of the *A. flavus* elicitor was as follows: after suspension culture of *C. roseus* CMCs for 6 day, 25 mg/L *A. flavus* mycelium elicitor were added, and the CMC suspensions were further cultured for another 48 h. In this condition, the contents of vindoline, catharanthine, and ajmaline were 1.45-, 3.29-, and 2.14-times as high as those of the control group, respectively. Transcriptome analysis showed that *D4H*, *G10H*, *GES*, *IRS*, *LAMT*, *SGD*, *STR*, *TDC*, and *ORCA3* were involved in the regulation of this induction process. The results of qRT-PCR indicated that the increasing accumulations of vindoline, catharanthine, and ajmaline in *C. roseus* CMCs were correlated with the increasing expression of the above genes. Therefore, *A. flavus* fungal elicitor could enhance the TIA production of *C. roseus* CMCs, which might be used as an alternative biotechnological resource for obtaining bioactive alkaloids.

**Keywords:** *Catharanthus roseus*; cambial meristematic cells; *Aspergillus flavus*; terpenoid indole alkaloids; biosynthesis
