Potato Glycoalkaloids: A Burden or a Blessing?

Abstract

Steroidal glycoalkaloids (SGAs) are produced following the general steroid biosynthesis pathway, starting from acetyl-coenzyme A and followed by the intermediates mevalonic acid, squalene, cycloartenol, and cholesterol. a-Chaconine and a-solanine are the main SGAs of the cultivated potato (Solanurn tuberosum), whereas many other SGAs are known in the wild potato species. Low concentrations of SGAs improve the taste of potato, but concentrations greater than 200 mgkg can have toxic effects on animals and humans. SGAs have antimicrobial activity and confer resistance to some insects, but many such pests of potato are not greatly affected. Certain environmental conditions and wounding enhance SGA accumulation in tubers in the field and storage. Low production of SGAs is a dominant character inherited in a relatively simple manner and can be selected for in potato-breeding programs, whereas the use of wild potato germplasm tends to increase the SGA accumulation in the breeding lines. Further efforts are likely to be directed toward the reduction of the SGA content in the edible potato products through breeding and biotechnological methodologies, whereas potato genotypes with high SGA production may be developed for use in the pharmaceutical industry.

Changes in the content of glycoalkaloids in potato tubers according to soil tillage and weed control methods

“…Removal of the potato skin reduces the content of glycoalkaloids in tubers, depending on various factors, by 51.5 to 55.1% (Zrůst et al 2000), 51.1 to 74.3% (Cieślik 1998) or even by 50-95% (Schwardt 1982, Valkonen et al 1996.…”

The effect of biostimulants and herbicides on glycoalkaloid accumulation in potato

“…However, when total glycoalkaloid (TGA) concentration exceeds 100 mg/kg fresh matter, it contributes to a decline in flavour, and when the accumulation exceeds 200 mg/kg fresh matter, TGA are toxic to humans (Valkonen et al 1996, Bejarano et al 2000. According to many authors (Percival and Dixon 1996, Wierzbicka 2011, Hamouz et al 2014, Zarzecka et al 2015, glycoalkaloid content is cultivar-specific but can also be affected by weather conditions during the growing season as well as cultivation methods applied.…”

Reduction of Cholesterol and Glycoalkaloid Levels in Transgenic Potato Plants by Overexpression of a Type 1 Sterol Methyltransferase cDNA

“…Mild clinical symptoms of glycoalkaloid poisoning include abdominal pain, vomiting, and diarrhea, and an upper safe limit in tubers of 200 mg total glycoalkaloids (TGA) kg Ϫ1 fresh weight has been recommended by leading authorities. However, this upper limit is close to levels found in tubers destined for human consumption, and efforts should be made to keep TGA levels low when introducing new varieties on the market (see Valkonen et al, 1996).The biosynthesis of glycoalkaloids in potato is currently not fully understood. Solanidine has been proposed to be synthesized from the key precursor in plant sterol synthesis, cycloartenol, in a biosynthetic route including cholesterol, a sterol lacking alkylations at the C-24 position in the side chain (Heftmann, 1983; Bergenstråhle et al, 1996;Friedman and McDonald, 1997; Fig.…”

“…Mild clinical symptoms of glycoalkaloid poisoning include abdominal pain, vomiting, and diarrhea, and an upper safe limit in tubers of 200 mg total glycoalkaloids (TGA) kg Ϫ1 fresh weight has been recommended by leading authorities. However, this upper limit is close to levels found in tubers destined for human consumption, and efforts should be made to keep TGA levels low when introducing new varieties on the market (see Valkonen et al, 1996).…”