Genetic modification of the soybean to enhance the β-carotene content through seed-specific expression

PLoS One. 2012;7(10):e48287. doi: 10.1371/journal.pone.0048287. Epub 2012 Oct 31.

Abstract

The carotenoid biosynthetic pathway was genetically manipulated using the recombinant PAC (Phytoene synthase-2A-Carotene desaturase) gene in Korean soybean (Glycine max L. cv. Kwangan). The PAC gene was linked to either the β-conglycinin (β) or CaMV-35S (35S) promoter to generate β-PAC and 35S-PAC constructs, respectively. A total of 37 transgenic lines (19 for β-PAC and 18 for 35S-PAC) were obtained through Agrobacterium-mediated transformation using the modified half-seed method. The multi-copy insertion of the transgene was determined by genomic Southern blot analysis. Four lines for β-PAC were selected by visual inspection to confirm an orange endosperm, which was not found in the seeds of the 35S-PAC lines. The strong expression of PAC gene was detected in the seeds of the β-PAC lines and in the leaves of the 35S-PAC lines by RT-PCR and qRT-PCR analyses, suggesting that these two different promoters function distinctively. HPLC analysis of the seeds and leaves of the T(2) generation plants revealed that the best line among the β-PAC transgenic seeds accumulated 146 µg/g of total carotenoids (approximately 62-fold higher than non-transgenic seeds), of which 112 µg/g (77%) was β-carotene. In contrast, the level and composition of the leaf carotenoids showed little difference between transgenic and non-transgenic soybean plants. We have therefore demonstrated the production of a high β-carotene soybean through the seed-specific overexpression of two carotenoid biosynthetic genes, Capsicum phytoene synthase and Pantoea carotene desaturase. This nutritional enhancement of soybean seeds through the elevation of the provitamin A content to produce biofortified food may have practical health benefits in the future in both humans and livestock.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Agrobacterium / genetics
  • Alkyl and Aryl Transferases / genetics
  • Free Radical Scavengers / metabolism
  • Gene Expression
  • Genetic Engineering / methods*
  • Geranylgeranyl-Diphosphate Geranylgeranyltransferase
  • Glycine max / genetics*
  • Glycine max / metabolism*
  • Organ Specificity
  • Phytosterols / metabolism
  • Pigmentation / genetics
  • Plants, Genetically Modified
  • Recombinant Proteins / genetics
  • Seeds / genetics*
  • Seeds / metabolism*
  • Tocopherols / metabolism
  • Transformation, Genetic
  • Transgenes / genetics
  • beta Carotene / biosynthesis
  • beta Carotene / metabolism*

Substances

  • Free Radical Scavengers
  • Phytosterols
  • Recombinant Proteins
  • beta Carotene
  • Alkyl and Aryl Transferases
  • Geranylgeranyl-Diphosphate Geranylgeranyltransferase
  • Tocopherols

Grants and funding

This work was supported by the Rural Development Administration (Code PJ006834 to SHH) and a grant from the Next-Generation BioGreen 21 Program (Code PJ008184 to SHH and PJ007978 to YSC), Rural Development Administration, Republic of Korea. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.