Isolation of UDP:flavonoid 3-<i>O</i>-glycosyltransferase (UFGT)-like Genes and Expression Analysis of Genes Associated with Anthocyanin Accumulation in Mango ‘Irwin’ skin

Abstract

The red coloration of the mango 'Irwin' skin is an important factor determining its value in the Japanese domestic luxury fruit market. In the present study, to investigate the molecular mechanism underlying anthocyanin biosynthesis of mango fruit skin, UFGT-like genes were isolated and the expression profile of anthocyanin-related genes was determined. Several UFGT-like genes were identified in transcriptome data of red 'Irwin' mango skin and two genes, MiUFGT1 and MiUFGT3, were considered to be involved in mango skin coloration. Deduced amino acid sequences of these genes exhibited high similarity to other plant UFGTs and contained the conserved PSPG box common to the glycosyltransferase family. The presence of a glutamine and a histidine residue at the C-terminus end of the PSPG box in MiUFGT1 and MiUFGT3, respectively, implied that MiUFGT1 and MiUFGT3 use glucose and galactose, respectively, as a sugar donor; however, the actual function and sugar donor preference of these enzymes remain to be elucidated. Expression analysis of anthocyanin-related genes during skin coloration suggested that MiCHS and MiANS, as well as MiUFGT1 and MiUFGT3, play important roles in the anthocyanin biosynthesis of mango fruit skin and that the expression of these genes is regulated by the MYB transcription factor, as reported in other plant species.

Characterization of the Recombinant UDP:flavonoid 3-<i>O</i>-galactosyltransferase from <i>Mangifera indica</i> ‘Irwin’ (MiUFGalT3) involved in Skin Coloring

“…In conclusion, MiUFGalT3, which was referred to as MiUFGT3 in our previous study (Kanzaki et al, 2019), was found to have relatively high galactosyltransferase activity. Considering the expression profile reported previously (Kanzaki et al, 2019) and its functional preference for UDP-galactose as a sugar donor, MiUFGalT3 rather than MiUFGT1 plays a crucial role in the light-induced red coloration of the mango fruit skin. Our findings may provide an important clue to elucidate the mechanism of anthocyanin accumulation in mango fruit skin.…”

“…On the other hand, VvGT5 and VvGT6, which share 91% amino acid sequence identity and are located in tandem on a chromosome different from that containing VvGT1, use UDP-glucuronic acid and UDP-Gal/Glc, as sugar donors, respectively, and use flavonols as acceptor substrates (Ono et al, 2010). In the present study, the function and biochemical nature of the two recombinant UFGTs were elucidated, but it is possible that other plant GTs such as MiUFGT4, which was isolated in our previous study (Kanzaki et al, 2019), contribute in part to the glycosylation of the diverse phenolic compounds in the mango peel (Berardini et al, 2005a). Further investigation is required to understand the divergence and division in the roles of glycosyltransferase family mem-bers in mangoes.…”

“…However, the extent to which the residue contributes to donor specificity is controversial (Offen et al, 2006;Ono et al, 2010). The corresponding residues of MiUFGT1 and MiUFGT3 (MiUFGalT3) are Gln and His, respectively (Kanzaki et al, 2019). rMiUFGT1 expressed in E. coli as a GST fusion showed weak glucosyltransferase activity, suggesting that MiUFGT1 may have mutations at the sites associated with its activity.…”

“…Recently, several molecular studies of anthocyanin biosynthesis in mangoes have been published (Bajpai et al, 2018;Hoang et al, 2015;Kanzaki et al, 2019;Karanjalker et al, 2018a, b). In our previous study, we isolated two UFGT genes, MiUFGT1 and MiUFGT3, from mango fruit skin and showed that the expression of both genes was upregulated by light exposure, which induced anthocyanin accumulation in the fruit skin (Kanzaki et al, 2019). This suggests that these two genes play important regulatory roles in anthocyanin accumulation in mangoes.…”

RNA-Seq reveals the key pathways and genes involved in the light-regulated flavonoids biosynthesis in mango (Mangifera indica L.) peel

“…Mango ( Mangifera indica L.) is the fifth most produced fruit crop worldwide ( ), which is widely cultivated in tropical and subtropical areas in the world. So far, the molecular mechanism of flavonoids biosynthesis in mango is mainly focusing on the expression changes of flavonoids biosynthetic genes and MBW complex by different treatments or in different cultivars ( Hoang et al., 2015 ; Kanzaki et al., 2019 ; Kanzaki et al., 2020 ), while how these genes are regulated by the up-stream TFs is still unknown. In the previous study, we found bagging treatment significantly decreased the anthocyanins and flavonols but surprisingly increased the proanthocyanidins accumulation in the fruit peel of red mango cultivar ‘Sensation’ ( Shi et al., 2021 ), which was very different from the other studies since light generally promotes all flavonoids compounds accumulation including flavonols, anthocyanins and proanthocyanidins ( Cortell and Kennedy, 2006 ; Li et al., 2021 ).…”