Comparative Transcriptome Analysis Identifies Genes Putatively Involved in 20-Hydroxyecdysone Biosynthesis in Cyanotis arachnoidea

Abstract

Cyanotis arachnoidea contains a rich array of phytoecdysteroids, including 20-hydroxyecdysone (20E), which displays important agrochemical, medicinal, and pharmacological effects. To date, the biosynthetic pathway of 20E, especially the downstream pathway, remains largely unknown. To identify candidate genes involved in 20E biosynthesis, the comparative transcriptome of C. arachnoidea leaf and root was constructed. In total, 86.5 million clean reads were obtained and assembled into 79,835 unigenes, of which 39,425 unigenes were successfully annotated. The expression levels of 2427 unigenes were up-regualted in roots with a higher accumulation of 20E. Further assignments with Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways identified 49 unigenes referring to the phytoecdysteroid backbone biosynthesis (including 15 mevalonate pathway genes, 15 non-mevalonate pathway genes, and 19 genes for the biosynthesis from farnesyl pyrophosphate to cholesterol). Moreover, higher expression levels of mevalonate pathway genes in roots of C. arachniodea were confirmed by real-time quantitative PCR. Twenty unigenes encoding CYP450s were identified to be new candidate genes for the bioreaction from cholesterol to 20E. In addition, 90 transcription factors highly expressed in the roots and 15,315 unigenes containing 19,158 simple sequence repeats (SSRs) were identified. The transcriptome data of our study provides a valuable resource for the understanding of 20E biosynthesis in C. arachnoidea.

Transcriptome and Metabolome Analysis of the Synthesis Pathways of Allelochemicals in Eupatorium adenophorum

“…In ginsenoside-producing plants, the core genes of the MVA pathway show a relatively high expression in the roots. 37,38 These two findings indicate that the general biology of these plants differs from that of E. adenophorum.…”

“…In contrast, the expression of MVA pathway genes is relatively high in the roots of the perennial plant Cyanotis arachnoidea . In ginsenoside-producing plants, the core genes of the MVA pathway show a relatively high expression in the roots. , These two findings indicate that the general biology of these plants differs from that of E. adenophorum .…”