The genetic control of polyacetylenes involved in bitterness of carrots (Daucus carota L.): Identification of QTLs and candidate genes from the plant fatty acid metabolism

Abstract

Background Falcarinol-type polyacetylenes (PAs) such as falcarinol (FaOH) and falcarindiol (FaDOH) are produced by several Apiaceae vegetables such as carrot, parsnip, celeriac and parsley. They are known for numerous biological functions and contribute to the undesirable bitter off-taste of carrots and their products. Despite their interesting biological functions, the genetic basis of their structural diversity and function is widely unknown. A better understanding of the genetics of the PA levels present in carrot roots might support breeding of carrot cultivars with tailored PA levels for food production or nutraceuticals. Results A large carrot F2 progeny derived from a cross of a cultivated inbred line with an inbred line derived from a Daucus carota ssp. commutatus accession rich in PAs was used for linkage mapping and quantitative trait locus (QTL) analysis. Ten QTLs for FaOH and FaDOH levels in roots were identified in the carrot genome. Major QTLs for FaOH and FaDOH with high LOD values of up to 40 were identified on chromosomes 4 and 9. To discover putative candidate genes from the plant fatty acid metabolism, we examined an extended version of the inventory of the carrot FATTY ACID DESATURASE2 (FAD2) gene family. Additionally, we used the carrot genome sequence for a first inventory of ECERIFERUM1 (CER1) genes possibly involved in PA biosynthesis. We identified genomic regions on different carrot chromosomes around the found QTLs that contain several FAD2 and CER1 genes within their 2-LOD confidence intervals. With regard to the major QTLs on chromosome 9 three putative CER1 decarbonylase gene models are proposed as candidate genes. Conclusion The present study increases the current knowledge on the genetics of PA accumulation in carrot roots. Our finding that carrot candidate genes from the fatty acid metabolism are significantly associated with major QTLs for both major PAs, will facilitate future functional gene studies and a further dissection of the genetic factors controlling PA accumulation. Characterization of such candidate genes will have a positive impact on carrot breeding programs aimed at both lowering or increasing PA concentrations in carrot roots.

Sensory Perception and Consumer Acceptance of Carrot Cultivars Are Influenced by Their Metabolic Profiles for Volatile and Non-Volatile Organic Compounds

“…In our sensory study, falcarinol was not correlated with bitterness, whereas falcarindiol and especially its putative derivative falcarindiol-3-acetate were highly correlated with bitterness and off-flavor. Breeding approaches using molecular markers for key enzymes of polyacetylene synthesis might reduce unwanted polyacetylenes to an appropriate level and be helpful to improv consumer acceptance [21]. The highest concentrations by far for falcarindiol and falcarindiol-3-acetate were determined for the least appreciated cultivar 'Brasilia'.…”

“…The availability of a high-quality carrot reference genome sequence [16] has enabled 'multiomics' approaches. In combination with transgenic and classical genetic tools, these advances now make it far easier to identify key phytochemicals with a decisive influence on carrot flavor and liking scores [3,[17][18][19][20][21][22].…”

Comprehensive evolutionary analysis of the FAD2 gene family in representatives of campanulids: identification and characterization of candidate genes from the plant polyacetylene metabolism

“…To understand how FAD2 genes related to polyacetylenes evolved in the context of the major energy product changing from fatty acids in most land plants to PAs in many species in campanulids, this study rst performed comprehensive evolutionary analyses of FAD2 genes in the three most representative plant families of PA source. Although there were some early published studies related to FAD2 genes in campanulid plants [21,36,37,38,39], they were only focused on one species. Compared with two of these previous studies [21,37], the number of genes identi ed in the present study is slightly smaller, due to ltration methodology of removing sequences without those 8 conserved histidine residues.…”

Understanding of genes encoding bioactive compounds from potential medicinal plants in Indonesia as cancer cell inhibitors

“…As a single variant gene, the FAD2 gene was discovered in Arabidopsis and was shown to be constitutively expressed (Peng et al 2020). Other researchers have studied various types of FAD2 in different potential medicinal species of plants, including Camelina sativa (Neumann et al 2021); Daucus carota L. (Dunemann et al 2022); Arachis hypogaea L. (Gangadhara and Nadaf 2016); Idesia polycarpa (Fan et al 2019); and G. max (Lakhssassi et al 2017). FAD2 genes have been successfully characterized in tomato (Solanum lycopersicum) medicine plants in terms of primary metabolism and stress response (Lee et al 2020).…”