Inulin chain length modification using a transgenic approach opening new perspectives for chicory

Abstract

Chicory capable of synthesizing long-chain inulin is of great interest. During the growing season, the sucrose-sucrose 1-fructosyltransferase (1-SST) activity is vital for production of long-chain inulin in chicory. With the purpose to increase inulin chain length, we employed -mediated transformation method. Transgenic chicory plants ( L. var. ) cv. 'Melci' has been developed to overexpress sucrose-sucrose 1-fructosyltransferase (1-SST) under the control of the CaMV 35S promoter. The integration of the T-DNA into the plant genome was confirmed by PCR on genomic DNA using gene-specific primers. Quantification of the 1-SST transcript expression level revealed that transgenic plants showed higher 1-SST expression than those in non-transgenic plants. Further analyses proved that the fructan content of the roots significantly increased in the transgenic plants. These results revealed that overexpression of the, the key gene in inulin biosynthesis in chicory, might serve as a novel approach to develop plants with the long-chain inulin content.

Towards a Cardoon (Cynara cardunculus var. altilis)-Based Biorefinery: A Case Study of Improved Cell Cultures via Genetic Modulation of the Phenylpropanoid Pathway

“…The analyses of the transgenic lines proved that the CaMV35S promoter is suitable for overexpression strategies also in cardoon cells, as already shown for other Asteraceae such as artichoke [ 62 ], chicory ( Cichorium intybus var. sativum L., [ 63 ]), and gerbera ( Gerbera jamesonii , [ 64 ]). The three independent lines selected for this study overexpressed the transgene at significantly different levels, allowing for the exploration dose-dependent phenotypes.…”

The differential expression of the two key genes involved in fructans biosynthetic pathway in artichoke vs wild cardoon improves inulin-type fructans

“…The artichoke 1-SST gene (GenBank: Y09662.1) forward primer 5'-CGAGATAGGCACAGCAACAC-3' reverse primer 5'-GCTTCAAGCGTCGATTCCAA-3' and artichoke 1-FFT gene (GenBank: AJ000481.2) forward primer 5'-GGAAGGTTCTTTGCGTCGAA-3' reverse primer 5'-CGTCTTGGTCGTAACTGTCG-3', were used. The artichoke ACTIN gene (GenBank: AM744951.1) forward primer 5'-TGCTGGATTCTGGAGATGGT-3' reverse primer 5'-ATCAAGACGGAGGATGGCAT-3', was used as an endogenous reference to normalize, as reported by Marou et al (2018). The results were analyzed using STEP One Software 2.0 (Applied Biosystems), using the 2 −ΔΔCt method (Schmittgen and Livak 2008).…”

Ectopic Expression of the Allium cepa 1-SST Gene in Cotton Improves Drought Tolerance and Yield Under Drought Stress in the Field

“…Specifically, 1-SST is responsible for transferring the fructosyl moiety from one sucrose molecule to another to form a 1-kestose and release a glucose molecule, via the irreversible reaction: ( Edelman and Jefford, 1968 ; Koops and Jonker, 1994 ; Lüscher et al, 1996 ; Van Den Ende et al, 1996 ). A recent study showed that overexpression of 1-SST was essential for production of long-chain inulin in chicory ( Maroufi et al, 2018 ). In addition, fructans, like starch and sucrose, are important stored forms of carbohydrate, and are also closely related to the regulation of plant carbon allocation and sucrose-pool ( Pollock, 1986 ; Nelson and Spollen, 1987 ).…”