molecules Article De Novo RNA Sequencing and Expression Analysis of Aconitum carmichaelii to Analyze Key Genes Involved in the Biosynthesis of Diterpene Alkaloids Megha Rai 1, Amit Rai 1,* ID , Noriaki Kawano 2, Kayo Yoshimatsu 2, Hiroki Takahashi 3, Hideyuki Suzuki 4, Nobuo Kawahara 2, Kazuki Saito 1 ID and Mami Yamazaki 1,* ID 1 Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan;
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[email protected] (M.Y.); Tel.: +81-043-226-2933 (M.Y.) Received: 16 November 2017; Accepted: 1 December 2017; Published: 5 December 2017 Abstract: Aconitum carmichaelii is an important medicinal herb used widely in China, Japan, India, Korea, and other Asian countries. While extensive research on the characterization of metabolic extracts of A. carmichaelii has shown accumulation of numerous bioactive metabolites including aconitine and aconitine-type diterpene alkaloids, its biosynthetic pathway remains largely unknown. Biosynthesis of these secondary metabolites is tightly controlled and mostly occurs in a tissue-specific manner; therefore, transcriptome analysis across multiple tissues is an attractive method to identify the molecular components involved for further functional characterization.