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932 results on '"Bak, Søren"'

1. Bak, Søren Alex

Author

Bak, Søren Alex and Bak, Søren Alex

Published
2008

2. Bak, Søren

Author

Bak, Søren and Bak, Søren

Published
2008

9. Site‐directed genotype screening for elimination of antinutritional saponins in quinoa seeds identifies TSARL1 as a master controller of saponin biosynthesis selectively in seeds.

Author

Trinh, Mai Duy Luu, Visintainer, Davide, Günther, Jan, Østerberg, Jeppe Thulin, da Fonseca, Rute R., Fondevilla, Sara, Moog, Max William, Luo, Guangbin, Nørrevang, Anton F., Crocoll, Christoph, Nielsen, Philip V., Jacobsen, Sven‐Erik, Wendt, Toni, Bak, Søren, López‐Marqués, Rosa Laura, and Palmgren, Michael

Subjects
QUINOA, SAPONINS, AGRICULTURAL productivity, SEEDS, BIOSYNTHESIS, SEED coats (Botany)
Abstract

Summary: Climate change may result in a drier climate and increased salinization, threatening agricultural productivity worldwide. Quinoa (Chenopodium quinoa) produces highly nutritious seeds and tolerates abiotic stresses such as drought and high salinity, making it a promising future food source. However, the presence of antinutritional saponins in their seeds is an undesirable trait. We mapped genes controlling seed saponin content to a genomic region that includes TSARL1. We isolated desired genetic variation in this gene by producing a large mutant library of a commercial quinoa cultivar and screening the library for specific nucleotide substitutions using droplet digital PCR. We were able to rapidly isolate two independent tsarl1 mutants, which retained saponins in the leaves and roots for defence, but saponins were undetectable in the seed coat. We further could show that TSARL1 specifically controls seed saponin biosynthesis in the committed step after 2,3‐oxidosqualene. Our work provides new important knowledge on the function of TSARL1 and represents a breakthrough for quinoa breeding. [ABSTRACT FROM AUTHOR]

Published
2024
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33. Phytoalexins of the crucifer Barbarea vulgaris:Structural profile and correlation with glucosinolate turnover

Author

Cárdenas, Pablo D., Landtved, Jonas P., Larsen, Signe H., Lindegaard, Nicolai, Wøhlk, Sebastian, Jensen, Karen R., Pattison, David I., Burow, Meike, Bak, Søren, Crocoll, Christoph, Agerbirk, Niels, Cárdenas, Pablo D., Landtved, Jonas P., Larsen, Signe H., Lindegaard, Nicolai, Wøhlk, Sebastian, Jensen, Karen R., Pattison, David I., Burow, Meike, Bak, Søren, Crocoll, Christoph, and Agerbirk, Niels

Abstract

Phytoalexins are antimicrobial plant metabolites elicited by microbial attack or abiotic stress. We investigated phytoalexin profiles after foliar abiotic elicitation in the crucifer Barbarea vulgaris and interactions with the glucosinolate-myrosinase system. The treatment for abiotic elicitation was a foliar spray with CuCl2 solution, a usual eliciting agent, and three independent experiments were carried out. Two genotypes of B. vulgaris (G-type and P-type) accumulated the same three major phytoalexins in rosette leaves after treatment: phenyl-containing nasturlexin D and indole-containing cyclonasturlexin and cyclobrassinin. Phytoalexin levels were investigated daily by UHPLC-QToF MS and tended to differ among plant types and individual phytoalexins. In roots, phytoalexins were low or not detected. In treated leaves, typical total phytoalexin levels were in the range 1–10 nmol/g fresh wt. during three days after treatment while typical total glucosinolate (GSL) levels were three orders of magnitude higher. Levels of some minor GSLs responded to the treatment: phenethylGSL (PE) and 4-substituted indole GSLs. Levels of PE, a suggested nasturlexin D precursor, were lower in treated plants than controls. Another suggested precursor GSL, 3-hydroxyPE, was not detected, suggesting PE hydrolysis to be a key biosynthetic step. Levels of 4-substituted indole GSLs differed markedly between treated and control plants in most experiments, but not in a consistent way. The dominant GSLs, glucobarbarins, are not believed to be phytoalexin precursors. We observed statistically significant linear correlations between total major phytoalexins and the glucobarbarin products barbarin and resedine, suggesting that GSL turnover for phytoalexin biosynthesis was unspecific. In contrast, we did not find correlations between total major phytoalexins and raphanusamic acid or total glucobarbarins and barbarin. In conclusion, two groups of phytoalexins were detected in B. vulgar

Published
2023

34. Lessons learned from metabolic engineering in hairy roots:Transcriptome and metabolic profile changes caused by Rhizobium-mediated plant transformation in Cucurbitaceae species

Author

Almeida, Aldo, Favero, Bruno Trevenzoli, Dong, Lemeng, Cárdenas, Pablo D., Saenz-Mata, Jorge, Lütken, Henrik, Bak, Søren, Almeida, Aldo, Favero, Bruno Trevenzoli, Dong, Lemeng, Cárdenas, Pablo D., Saenz-Mata, Jorge, Lütken, Henrik, and Bak, Søren

Abstract

Cucurbitaceae species are used in traditional medicine around the world. Cucurbitacins are highly oxygenated triterpenoids found in Cucurbitaceae species and exhibit potent anticancer activity alone and in combination with other existing chemotherapeutic drugs. Therefore, increasing production of these specialized metabolites is of great relevance. We recently showed that hairy roots of Cucurbita pepo can be used as a platform for metabolic engineering of cucurbitacins to modify their structure and increase their production. To study the changes in cucurbitacin accumulation upon formation of hairy roots, an empty vector (EV) control and Cucurbitacin inducing bHLH transcription factor 1 (CpCUCbH1)-overexpressing hairy roots of C. pepo were compared to untransformed (WT) roots. Whilst CpCUCbH1-overexpression increased production of cucurbitacins I and B by 5-fold, and cucurbitacin E by 3-fold when compared to EV lines, this increase was not significantly different when compared to WT roots. This indicated that Rhizobium rhizogenes transformation lowered the cucurbitacins levels in hairy roots, but that increasing expression of cucurbitacin biosynthetic genes by CpCUCbH1-overexpression restored cucurbitacin production to WT levels. Subsequent metabolomic and RNA-seq analysis indicated that the metabolic profile and transcriptome of hairy roots was significantly changed when compared to WT roots. Interestingly, it was observed that 11% of the differentially expressed genes were transcription factors. It was noteworthy that the majority of transcripts showing highest Pearson correlation coefficients to the Rhizobium rhizogenes genes rolB, rolC and ORF13a, were predicted to be transcription factors. In summary, hairy roots are an excellent platform for metabolic engineering of plant specialized metabolites, but these extensive transcriptome and metabolic profile changes should be considered in subsequent studies.

Published
2023

35. The saponin bomb: a nucleolar‐localized β‐glucosidase hydrolyzes triterpene saponins in Medicago truncatula

Author

Lacchini, Elia, primary, Erffelinck, Marie‐Laure, additional, Mertens, Jan, additional, Marcou, Shirley, additional, Molina‐Hidalgo, Francisco Javier, additional, Tzfadia, Oren, additional, Venegas‐Molina, Jhon, additional, Cárdenas, Pablo D., additional, Pollier, Jacob, additional, Tava, Aldo, additional, Bak, Søren, additional, Höfte, Monica, additional, and Goossens, Alain, additional

Published
2023
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