Evaluation of Solasonine Content and Expression Patterns of SGT1 Gene in Different Tissues of Two Iranian Eggplant (Solanum melongena L.) Genotypes

Abstract

The family of Solanaceae (also known as nightshade family) is considered as a large plant family including essential crops such as potato, tomato, sweet pepper and lastly eggplant (1). In both tropical and temperate regions of the world, eggplant (Solanum melongena L., 2n=2x=24) has been cultivated for years, and regarded currently as an economically important vegetable plant (2). Phylogenetically, contrary to the other important Solanaceae fam- SummaryEggplant (Solanum melongena L.) is one of the most consumed vegetables in the world. The eggplant glycoalkaloids (GAs) are toxic secondary metabolites that may have detrimental effects on human health, particularly if the magnitudes of GAs are higher than the recommended food safety level (200 mg per kg of fresh mass). In this study, the content of solasonine compound and the expression patterns of solasodine galactosyltransferase (SGT1) gene were assessed in different tissues (mature leaves, flower buds, young, mature, and physiologically ripe fruits) of two Iranian eggplant genotypes (D1 and J10) under field conditions. The maximum mass fraction of solasonine in D1 was detected in flower buds (135.63 μg/g), followed by leaf (113.29 μg/g), physiologically ripe fruit (74.74 μg/g), young fruit (61.33 μg/g), and mature fruit (21.55 μg/g). Comparing both genotypes, the genotype of bitter fruits (J10) contained higher mass fraction of solasonine, as one of the main factors for producing bitter flavour of the plant. Regarding the expression profiles of SGT1, in both genotypes, the activity of the gene was increased nearly parallel with the concentration of solasonine. In the J10 geno type, transcript level of the gene was significantly higher than the genotype of sweet fruits (D1). Although both D1 and J10 genotypes are possibly recommendable for human food consumption, D1 is more suitable for daily diet.

Health benefits and bioactive compounds of eggplant

“…Researchers showed that SGAs have an antiparasitic effect on Leishmania mexicana (Lezama-Dávila et al, 2016), Leishmania amazonensis (Miranda et al, 2013) and Trypanosoma cruzi (Hall, Hobby & Cipollini, 2006;Chataing, Concepción, Lobatón, & Usubillaga, 1998). Although they have beneficial effects, glycoalkaloids are toxic to humans and can even cause death at high concentrations (3-5 mg/kg body mass) (Bagheri, Bushehri, Hassandokht & Naghavi, 2017). Market eggplant, S. melongena, has lower levels of glycoalkaloids than the toxic dose (Table S3).…”

“…Glycoalkaloids are found at different concentrations in different parts of the plants and at different developmental stages as is the case with different wild relatives and varieties of eggplant. The highest solasodine content was observed in flower buds, followed by leaf, physiologically ripe fruit, young fruit, and mature fruit (Bagheri et al, 2017). It is well known that glycoalkaloids are effective inhibitors of cancer cells due to their toxic effects.…”

Risk assessment of glycoalkaloids in feed and food, in particular in potatoes and potato‐derived products

“…Bagheri et al. () compared two different aubergine genotypes, of which one (D1) had ‘sweet’ fruits and the other (J10) had ‘bitter’ fruits, with regard to the content of α‐solasonine (α‐solamargine was not analysed in this study) as well as concerning the expression of SGT1 in the leaves, flower buds, young fruits, mature fruits and physiologically ripe fruits. The levels of α‐solasonine closely followed the expression of the SGT1 gene in the same plant tissues.…”

“…In all tissues, the concentration of α‐solasonine in the bitter variety was between two and three times higher than in the sweet variety. Concentrations of α‐solasonine reported for the D1 and J10 genotypes, respectively, were leaves: 113.3 and 249.3 mg/kg dw; flower buds: 135.6 and 478.8 mg/kg dw; young fruits: 61.3 and 160.4 mg/kg dw; mature fruits: 21.6 and 45.6 mg/kg dw and physiologically ripe fruits: 74.7 and 185.0 mg/kg dw (Bagheri et al., ).…”

Genetic Diversity and Utilization of Cultivated Eggplant Germplasm in Varietal Improvement

“…In addition, literature has shown that the SGAs have an antiparasitic effect on Trypanosoma cruzi , Leishmania amazonensis, and Leishmania mexicana [ 21 ]. Though glycoalkaloids have beneficial effects as inhibitors of cancer cells, they are also toxic to humans and can cause death if injected in higher concentrations at 3 to 5 mg/kg body mass [ 25 ]. Therefore, the optimal levels for toxicity should be further studied.…”