Novel Insights into Anthocyanin Metabolism and Molecular Characterization of Associated Genes in Sugarcane Rinds Using the Metabolome and Transcriptome

Abstract

Saccharum officinarum (sugarcane) is the fifth major cultivated crop around the world. Sugarcane rind is a promising source for anthocyanin pigments; however, limited information is available on the anthocyanin and its biosynthesis in sugarcane rinds. In this study, we have quantified 49 compounds including 6 flavonoids and 43 anthocyanins in the rind of 6 sugarcane cultivars by using LCMS/MS approach. Thirty of them were quantified for the first time in sugarcane. The 43 anthocyanins included 10 cyanidin (Cya), 11 pelargonidin (Pel), 9 peonidin (Peo), 5 malvidin (Mal), 4 delphinidin (Del), and 4 petunidin (Pet) metabolites. High contents of Cya derivatives were observed in the rind of YT71/210 (dark purple rind), such as cya-3-O-(6-O-malonyl)-glu 1283.3 µg/g and cya-3-O-glu 482.67 µg/g followed by ROC22 (red rind) 821.3 µg/g and 409 µg/g, respectively, whereas the YT93/159 (green rind) showed a minimum level of these compounds. Among six cultivars, ROC22 rind has high levels of Peo derivatives such as peo-3-O-glu (197 µg/g), peo-3-O-(6-O-malonyl)-glu (69 µg/g) and peo-3-O-(6-O-p-coumaryl)-glu (55.17 µg/g). The gene expression analysis revealed that some genes, including a MYB(t) gene, were highly associated with the color phenotype. Thus, we cloned and overexpressed the gene in Arabidopsis and found the pinkish brown color in the hypocotyl of all transgenic lines compared with the wild type. Hence, we have quantified a wide range of anthocyanins in major sugarcane cultivars, reported many new anthocyanins for the first time, and concluded that Cya and Peo derivatives are the major contributing factor of dissimilar colors in sugarcane. The finding and the verification of a novel MYB gene involved in anthocyanin biosynthesis have demonstrated that our study was very valuable for gene discovery and genetic improvement of sugarcane cultivars to harvest high anthocyanin contents.

Transcriptomic and Widely Targeted Metabolomic Approach Identified Diverse Group of Bioactive Compounds, Antiradical Activities, and Their Associated Genes in Six Sugarcane Varieties

“…Therefore, plants sustain their defense, growth and development, and environmental responses, by directing ~30% of photo-synthetic carbon toward amino acid formation [ 44 , 45 ]. The sugarcane rind also contains a substantial proportion of phenolics, flavonoids, alkaloids, anthocyanins, and terpenoids [ 2 , 3 , 32 ]. However, amino acids and organic acids have gained little attention in cane research, and only a few numbers of these compounds have been reported in sugarcane varieties.…”

“…In plants, MYB transcription factor genes are involved in biosynthesis of amino acids, phenolics, lignin, flavonoids, anthocyanins, and also play a significant role in plant growth and development [ 2 , 43 , 45 , 49 , 50 ]. In rice, the overexpression of MYB transcription factor gene OsMYB55 stimulates amino acid metabolism and enhances the total amino acid contents in transgenic rice [ 49 ].…”

“…Heterologous expression of two maize (monocot) transcription factors significantly enhances the flavonoid contents in transgenic tomato (dicot) fruit [ 52 ]. Recently, an MYB gene from sugarcane has significantly induced the expression of anthocyanins biosynthesis genes and accumulated anthocyanin contents in the hypocotyls of transgenic Arabidopsis over the wild-type [ 2 ]. In Arabidopsis , MYB transcription factors are involved in the biosynthesis of several amino acids [ 50 ].…”

“…As a perennial crop, sugarcane encounters different abiotic and biotic stresses during its whole growth life. Consequently, sugarcane produces several bioactive compounds such as amino acid, organic acid, phenolic acid, flavonoids, anthocyanins, and proanthocyanidins to cope with these unfavorable environmental conditions [ 2 , 3 ]. The sugarcane rind plays a key role in protecting the stem sugar and produces many metabolites such as amino acids, organic acid alkaloids, phenolics, flavonoids, triterpenoids, etc., having strong antioxidants, antimicrobial, antibacterial, and antifungal activities.…”

A high-throughput lipidomics and transcriptomic approach reveals novel compounds from sugarcane linked with promising therapeutic potential against COVID-19

“…Sugarcane rind is a storehouse of several health-promoting metabolites that have significant nutritive, cosmetic, and pharmacological values (7,9). It is revealed that sugarcane rind possesses enormous kinds of metabolites such as lipids, carbohydrates, phenolics, alkaloids, aromatic amino acids, anthocyanins, phytosterols, flavonoids, triterpenoids, carotenoids, and other phytocompounds (10)(11)(12), which have diverse health-promoting properties such as anticancer, antiplatelet, antioxidant activity, antifungal, antibacterial, antiviral, anti-HIV activities quenching free radicals, and anti-inflammatory activities (13,14).…”