Insights into the Sesquiterpenoid Pathway by Metabolic Profiling and De novo Transcriptome Assembly of Stem-Chicory (Cichorium intybus Cultigroup “Catalogna”)

Abstract

Stem-chicory of the “Catalogna” group is a vegetable consumed for bitter-flavored stems. Type and levels of bitter sesquiterpene lactones (STLs) participate in conferring bitterness in vegetables. The content of lactucin—and lactucopocrin-like STLs was higher in “Molfettese” than “Galatina” landrace stalks, regardless of the cultivation sites, consistently with bitterness scores and gustative differences. The “Galatina” transcriptome assembly resulted in 58,872 unigenes, 77% of which were annotated, paving the way to molecular investigation of the STL pathway. Comparative transcriptome analysis allowed the identification of 69,352 SNPs and of 1640 differentially expressed genes that maintained the pattern independently of the site. Enrichment analyses revealed that 4 out of 29 unigenes were up-regulated in “Molfettese” vs “Galatina” within the sesquiterpenoid pathway. The expression of two germacrene A -synthase (GAS) and one -oxidase (GAO) genes of the costunolide branch correlated positively with the contents of lactucin-like molecules, supporting that STL biosynthesis regulation occurs at the transcriptional level. Finally, 46 genes encoding transcription factors (TFs) maintained a differential expression pattern between the two varieties regardless of the growth site; correlation analyses among TFs, GAS, GAO gene expressions and STLs contents suggest that one MYB and one bHLH may act in the pathway.

Metabolite variation in the lettuce gene pool: towards healthier crop varieties and food

“…For instance, the bitter compound deoxylactucin-sulphate (ID 1532) was relatively high in L. virosa, L. dregeana and L. tatarica . Jacquinelin (11,13-dihydro-8-deoxylactucin; ID 1497), a sesquiterpene-lactone related to bitterness in chicory (Testone et al 2016 ), was present in all accessions of L. saligna , in 2 out of the 21 L. serriola accessions and in both L. perennis accessions (Supplementary Table 2). With regard to red leaf colour, cyanidin-malonyl-glucoside (ID 484) was the main compound, based on its peak area of the HPLC-DAD profiles at 510 nm, and was detected in specific L. sativa accessions of cos, cutting and stalk lettuce, as well as in several accessions of wild species (Supplementary Table 2).…”

The Terpene Synthase Gene Family of Carrot (Daucus carota L.): Identification of QTLs and Candidate Genes Associated with Terpenoid Volatile Compounds

“…On the other side, in apple ( Malus domestica ) a comparatively small number of only 10 putative TPS genes is currently known and might be sufficient to account for the diversity of terpenes present in vegetative tissues and apple fruit (Nieuwenhuizen et al, 2013 ). Besides whole genome studies, transcriptome-based analysis of TPS genes has been performed in several non-model plants including the Asteraceae species Cichorium intybus (Testone et al, 2016 ) and Artemisia annua (Wang et al, 2009 ). Transcriptome analysis of the Apiaceae species Thapsia laciniata identified 17 unique TPS sequences among the assembled contigs (Drew et al, 2013 ).…”

BiodiverSO: A Case Study of Integrated Project to Preserve the Biodiversity of Vegetable Crops in Puglia (Southern Italy)

“…In a context of request for product quality standards and uniformity, Molfettese and Galatina chicories were characterized for some nutritive and quality traits as both fresh and ready-to-use products [22]. These local varieties, used both raw and cooked, represent a refined and nutritious vegetables, because of the presence of several healthy compounds as well as their low nitrate content [22,23,26].…”