ORCID Profile
0000-0001-9379-0862
Current Organisation
UiT Norges arktiske universitet
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Publisher: Wiley
Date: 04-08-2021
Abstract: Bilberry ( Vaccinium myrtillus L.) belongs to the Vaccinium genus, which includes blueberries ( Vaccinium spp.) and cranberry ( V . macrocarpon ). Unlike its cultivated relatives, bilberry remains largely undomesticated, with berry harvesting almost entirely from the wild. As such, it represents an ideal target for genomic analysis, providing comparisons with the domesticated Vaccinium species. Bilberry is prized for its taste and health properties and has provided essential nutrition for Northern European indigenous populations. It contains high concentrations of phytonutrients, with perhaps the most important being the purple colored anthocyanins, found in both skin and flesh. Here, we present the first bilberry genome assembly, comprising 12 pseudochromosomes assembled using Oxford Nanopore (ONT) and Hi‐C Technologies. The pseudochromosomes represent 96.6% complete BUSCO genes with an assessed LAI score of 16.3, showing a high conservation of synteny against the blueberry genome. Kmer analysis showed an unusual third peak, indicating the sequenced s les may have been from two in iduals. The alternate alleles were purged so that the final assembly represents only one haplotype. A total of 36,404 genes were annotated after nearly 48% of the assembly was masked to remove repeats. To illustrate the genome quality, we describe the complex MYBA locus, and identify the key regulating MYB genes that determine anthocyanin production. The new bilberry genome builds on the genomic resources and knowledge of Vaccinium species, to help understand the genetics underpinning some of the quality attributes that breeding programs aspire to improve. The high conservation of synteny between bilberry and blueberry genomes means that comparative genome mapping can be applied to transfer knowledge about marker‐trait association between these two species, as the loci involved in key characters are orthologous.
Publisher: Wiley
Date: 19-08-2021
DOI: 10.1111/NPH.17669
Abstract: The regulatory network of R2R3 MYB transcription factors in anthocyanin biosynthesis is not fully understood in blue‐coloured berries containing delphinidin compounds. We used blue berries of bilberry ( Vaccinium myrtillus ) to comprehensively characterise flavonoid‐regulating R2R3 MYBs, which revealed a new type of co‐regulation in anthocyanin biosynthesis between members of MYBA‐, MYBPA1‐ and MYBPA2‐subgroups. VmMYBA1 , VmMYBPA1.1 and VmMYBPA2.2 expression was elevated at berry ripening and by abscisic acid treatment. Additionally, VmMYBA1 and VmMYBPA1.1 expression was strongly downregulated in a white berry mutant. Complementation and transient overexpression assays confirmed VmMYBA1 and VmMYBA2 to induce anthocyanin accumulation. Promoter activation assays showed that VmMYBA1, VmMYBPA1.1 and VmMYBPA2.2 had similar activity towards dihydroflavonol 4‐reductase ( DFR ) and anthocyanidin synthase ( ANS ), but differential regulation activity for UDP‐glucose flavonoid 3‐ O ‐glucosyltransferase ( UFGT ) and flavonoid 3′5′‐hydroxylase ( F3′5′H ) promoters. Silencing of VmMYBPA1.1 in berries led to the downregulation of key anthocyanin and delphinidin biosynthesis genes. Functional analyses of other MYBPA regulators, and a member of novel MYBPA3 subgroup, associated them with proanthocyanidin biosynthesis and F3′5′H expression. The existence of 18 flavonoid‐regulating MYBs indicated gene duplication, which may have enabled functional ersification among MYBA, MYBPA1 and MYBPA2 subgroups. Our results provide new insights into the intricate regulation of the complex anthocyanin profile found in blue‐coloured berries involving regulation of both cyanidin and delphinidin branches.
Publisher: Oxford University Press (OUP)
Date: 21-06-2010
Abstract: Anthocyanins are important health-promoting phytochemicals that are abundant in many fleshy fruits. Bilberry (Vaccinium myrtillus) is one of the best sources of these compounds. Here, we report on the expression pattern and functional analysis of a SQUAMOSA-class MADS box transcription factor, VmTDR4, associated with anthocyanin biosynthesis in bilberry. Levels of VmTDR4 expression were spatially and temporally linked with color development and anthocyanin-related gene expression. Virus-induced gene silencing was used to suppress VmTDR4 expression in bilberry, resulting in substantial reduction in anthocyanin levels in fully ripe fruits. Chalcone synthase was used as a positive control in the virus-induced gene silencing experiments. Additionally, in sectors of fruit tissue in which the expression of the VmTDR4 gene was silenced, the expression of R2R3 MYB family transcription factors related to the biosynthesis of flavonoids was also altered. We conclude that VmTDR4 plays an important role in the accumulation of anthocyanins during normal ripening in bilberry, probably through direct or indirect control of transcription factors belonging to the R2R3 MYB family.
No related grants have been discovered for Laura Jaakola.