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Crop Biotech Update

Overexpression of BjHMGS1 Improves Health-Promoting Compounds in Tomato Fruit

October 18, 2017

The 3-Hydroxy-3-methylglutaryl-coenzyme A synthase (HMGS) codes for isoprenoids including phytosterols, which can lower blood cholesterol levels. In a previous study, overexpressing the mustard (Brassica juncea) BjHMGS1 gene in Arabidopsis and tobacco upregulated genes in the sterol biosynthesis and increased its sterol content. The team of Pan Liao of the University of Hong Kong aimed to overexpress the wildtype (HGMS) and mutant (S359A) BjHMGS1 genes in tomato (Solanum lycopersicum).

Overexpression of either gene caused an accumulation of MVA-derived squalene and phytosterols, as well as vitamin E and carotenoids, in tomato. In tomato with the HMGS-overexpressing seedlings, genes associated with the biosyntheses of universal precursors of several compounds, including phytosterols, brassinosteroids, carotenoids, and vitamin E were upregulated. However, the S359A-overexpressing tomato fruits had greater squalene and phytosterol contents over the HMGS-overexpressing plants.

This study demonstrates that manipulation of the BjHMGS1 gene is a potential strategy to simultaneously elevate health-promoting squalene, phytosterols, α-tocopherol, and carotenoids in tomato.

For more on this study, read the article in Plant Biotechnology Journal.