Regulation of sterol and glycoalkaloid biosynthesis in potato plants.

Glycoalkaloids are sterol-derived neurotoxic defence compounds that occur within the family Solanaceae (eg potato, tomato and eggplant). The most common glycoalkaloids in cultivated varieties of potato are α-solanine and α-chaconine. They are present in all parts of the plant, but sometimes at levels rendering tubers unsuitable, or even dangerous, for human consumption. Our goal is to reduce problems relating to glycoalkaloids in processing, production and consumption of potatoes, by increasing knowledge about glycoalkaloid biosynthesis and the changes of glycoalkaloid levels that occur in tubers from harvest to consumer.

We study the synthesis of sterols and glycoalkaloids in potatoes from different perspectives, including:

• the way different stresses increase sterol and glycoalkaloid content by activating key genes. By altering gene activity in transgenic plants, we can study their importance for different parts of the biosynthesis pathways.
• how glycoalkaloids are formed from sterols. By feeding with labeled sterol precursors and analysing the products formed, we try to describe the glycoalkaloid biosynthesis biochemically.
• the potato varieties that are particularly sensitive to stress with respect to glycoalkaloid formation. We analyse the stress-induced increase of glycoalkaloids and other alkaloids in 50 Swedish potatoes varieties.

Technically we use a combination of different methods within molecular biology, plant transgenics and analytical chemistry.

Selected publications

Arnqvist, L., Dutta, P., Jonsson, L., Sitbon, F. 2003. Reduction of glycoalkloid levels in transgenic potato plants by overexpression of a type-1 sterol methyltransferase cDNA. Plant Physiology 131:1792-1799

Arnqvist, L., Persson, M., Jonsson, L., Dutta, P., Sitbon, F. 2008. Overexpression of CYP710A1 and CYP710A4 in transgenic Arabidopsis plants increases the level of stigmasterol at the expense of sitosterol. Planta 227:309-317

Beste, L., Nahar, N., Dalman, K., Fujioka, S., Jonsson, L., Dutta, P., Sitbon, F. 2011. Synthesis of hydroxylated sterols in transgenic Arabidopsis plants alters growth and steroid metabolism. Plant Physiology 157:426-440

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