Genome-enabled discovery of anthraquinone biosynthesis in Senna tora

Abstract

Senna tora is a widely used medicinal plant. Its health benefits have been attributed to the large quantity of anthraquinones, but how they are made in plants remains a mystery. To identify the genes responsible for plant anthraquinone biosynthesis, we reveal the genome sequence of S. tora at the chromosome level with 526 Mb (96%) assembled into 13 chromosomes. Comparison among related plant species shows that a chalcone synthase-like (CHS-L) gene family has lineage-specifically and rapidly expanded in S. tora. Combining genomics, transcriptomics, metabolomics, and biochemistry, we identify a CHS-L gene contributing to the biosynthesis of anthraquinones. The S. tora reference genome will accelerate the discovery of biologically active anthraquinone biosynthesis pathways in medicinal plants.

Chromosomal Mapping of Tandem Repeats Revealed Massive Chromosomal Rearrangements and Insights Into Senna tora Dysploidy

“…Specifically, Senna tora L. (Roxb) (syn. Cassia tora L.) has been used traditionally as a dying agent, tea, or herbal medicine in several Asian countries, such as India, China, and Korea, and is now gaining global attention, prompting its genome sequencing initiative (Puri, 2018 ; Kang et al, 2020a ).…”

“…However, species with descending dysploid karyotypes of 2 n = 22–26 have also been reported, including S. tora with 2 n = 26 chromosomes (Pellerin et al, 2019 ). The taxonomic classification of S. tora and its related species is still ambiguous (Marazzi et al, 2006 ), and although the genome of S. tora has been released recently, no comprehensive comparative genomics with related Senna species has been performed to understand its genome evolution (Kang et al, 2020a ). Nevertheless, analyzing the abundance of repeats using short next-generation sequencing reads and their chromosomal distribution through fluorescence in situ hybridization (FISH) could provide relevant insights into the karyotype evolution and genome history of S. tora (Ruiz-Ruano et al, 2016 ; Novák et al, 2017 ).…”

Systemic Expression of Genes Involved in the Plant Defense Response Induced by Wounding in Senna tora

“…The reads were then mapped onto the S . tora reference genome [ 27 ], with an average mapping ratio of 97.8% ( Table S1 ).…”

Unravelling the puzzle of anthranoids metabolism in living plant cells using spectral imaging coupled to mass spectrometry

“…For years, the metabolism, biosynthesis and bioactivity of anthranoids were studied through chemical analysis of metabolites after feeding experiments with radiolabeled precursors (Gill, 2001), genome mining (Chiang et al, 2010;Kang et al, 2020) and bioassays (François et al, 1999;Gallé, 2015), respectively. Our study demonstrates that SImaging is an additional sensitive and suitable tool for the observation of anthranoids in vivo.…”

“…In plants, anthranoids are biosynthesized through two distinct pathways: the polyketide pathway occurs in the Rhamnaceae, Fabaceae, Aloeaceae, Polygonaceae families, while the shikimate/o-succinylbenzoic acid pathway in Rubiaceae (Han et al, 2001). Recently, genome mining identified new candidates for anthraquinones biosynthesis enzymes in Senna tora plants (Kang et al, 2020). Anthranoid metabolism has also been reported in mushrooms belonging the Cortinarius genus and in Aspergillus nidulans (Gill, 2001;Chiang et al, 2010).…”