Transcriptional Responses and GCMS Analysis for the Biosynthesis of Pyrethrins and Volatile Terpenes in Tanacetum coccineum

Abstract

Natural pyrethrins have been widely used as natural pesticides due to their low mammalian toxicity and environmental friendliness. Previous studies have mainly focused on Tanacetum cinerariifolium, which contains high levels of pyrethrins and volatile terpenes that play significant roles in plant defense and pollination. However, there is little information on T. coccineum due to its lower pyrethrin content and low commercial value. In this study, we measured the transcriptome and metabolites of the leaves (L), flower buds (S1), and fully blossomed flowers (S4) of T. coccineum. The results show that the expression of pyrethrins and precursor terpene backbone genes was low in the leaves, and then rapidly increased in the S1 stage before decreasing again in the S4 stage. The results also show that pyrethrins primarily accumulated at the S4 stage. However, the content of volatile terpenes was consistently low. This perhaps suggests that, despite T. coccineum and T. cinerariifolium having similar gene expression patterns and accumulation of pyrethrins, T. coccineum attracts pollinators via its large and colorful flowers rather than via inefficient and metabolically expensive volatile terpenes, as in T. cinerariifolium. This is the first instance of de novo transcriptome sequencing reported for T. coccineum. The present results could provide insights into pyrethrin biosynthetic pathways and will be helpful for further understanding how plants balance the cost–benefit relationship between plant defense and pollination.

TcbZIP60 positively regulates pyrethrins biosynthesis in Tanacetum cinerariifolium

“…Pyrethrins represent unique metabolites produced in pyrethrums that can provide plants with an effective endogenous chemical defense against insect and fungal diseases (Zeng et al, 2021). Since the 19th century, pyrethrins products have been gradually used as household and agricultural insecticides, and as insect-borne disease prevention agents (Orenstein, 1913;Lange and Akesson, 1973;Katsuda, 1999).…”

TcMYB8, a R3-MYB Transcription Factor, Positively Regulates Pyrethrin Biosynthesis in Tanacetum cinerariifolium

“…Then, to synthesize first-strand cDNA, 1 µg of total RNA was reverse transcribed using the TransScript ® One-Step gDNA Removal kit and cDNA Synthesis SuperMix kit (TransGen Biotech, Beijing, China). Three biological replicates were performed for each gene, with each replicate containing two technical repeats [ 5 ]. GADPH was used as an internal reference gene [ 17 ].…”

“…Although synthetic pyrethroids have been successfully used to control insect populations, consumers prefer using natural pyrethrins as an environmentally friendly and harmless alternative [ 3 ]. The pyrethrin content of T. cinerariifolium is as high as 2.5% in dry flowers [ 4 ], much higher than that of Tanacetum coccineum , which has been historically used as a source of pyrethrins [ 5 ]. However, how to further improve the pyrethrin content of pyrethrum remains a hot topic of research because of the annual increase in the demand for pyrethrins in the international market [ 6 ].…”

Overexpression of TcCHS Increases Pyrethrin Content When Using a Genotype-Independent Transformation System in Pyrethrum (Tanacetum cinerariifolium)

“…Relative quantitation by the real-time gene expression analysis of GUS and the reference gene GAPDH (GenBank accession no. ON398960) was performed using Applied Biosystems 7500 platform and SYBR ® green I with 6-carboxyl-X-rhodamine (Takara, Kusatsu, Japan), following a previously described protocol [46]. GUS-specific primers (GUS-RT-F, GUS-RT-R) and TcGAPDH-specific primers (TcGAPDH-RT-F, TcGAPDH-RT-R) were used (see Table S3).…”