The role of phytochromes in regulating biosynthesis of sterol glycoalkaloid in eggplant leaves

Abstract

Glycoalkaloids are toxic compounds that are synthesized by many Solanum species. Glycoalkaloid biosynthesis is influenced by plant genetic and environmental conditions. Although many studies have shown that light is an important factor affecting glycoalkaloid biosynthesis, the specific mechanism is currently unknown. Chlorophyll and carotenoid biosynthesis depend on light signal transduction and share some intermediate metabolites with the glycoalkaloid biosynthetic pathway. Here, we used virus-induced gene silencing to silence genes encoding phytoene desaturase (PDS) and magnesium chelatase (CHLI and CHLH) to reduce chlorophyll and carotenoid levels in eggplant leaves. Quantification of carotenoid and chlorophyll levels is analyzed by LC/PDA/APCI/MS and semipolar metabolite profiling by LC/HESI/MS. Notably, the resulting lines showed decreases in glycoalkaloid production. We further found that the expression of some genes involved in the production of glycoalkaloids and other metabolites were suppressed in these silenced lines. Our results indicate that photosynthetic pigment accumulation affects steroidal glycoalkaloid biosynthesis in eggplant leaves. This finding lays the foundation for reducing the levels of endogenous antinutritional compounds in crops.

Oviposition by Spodoptera exigua on Solanum dulcamara Alters the Plant’s Response to Herbivory and Impairs Larval Performance

“…These are precursors for a large variety of defensive secondary metabolites, such as different phenolics and alkaloids, but also for phytohormones such as auxin and JA [41]. For example, phenylalanine is the starting point of phenylpropanoid biosynthesis [42], glycine is suggested as a precursor for glycoalkaloid biosynthesis [43,44] and tryptophan is a precursor for auxin and indole, which can prime anti-herbivore defense in maize [45]. Thus, upon herbivore attack, plants may activate an amino acid metabolism to supply the precursors of the pathways producing defensive secondary metabolites.…”

Solanum steroidal glycoalkaloids: structural diversity, biological activities, and biosynthesis

“…23,149 These results suggest that SGA synthesis might be related to green pigments, such as chlorophyll. 18,22 The biosynthetic pathways of chlorophyll, carotenoid, and glycoalkaloid share a common intermediate, isopentenyl pyrophosphate (IPP); therefore, the biosynthesis of each of these three compounds influence that of the others. 22 Photosynthetic pigment accumulation affects steroidal glycoalkaloid biosynthesis in eggplant leaves.…”

“…1,6,10,16 Environmental factors including light exposure, temperature, drought, nitrogen fertilization, or wounding result in comparatively increased glycoalkaloid contents. 17–22 The total SGA content in the unstressed tubers also depends on the genotypes of commercial varieties. 21,23 Furthermore, the steroidal glycoalkaloids are well-known toxicants to animals and humans; however, they can also serve as drugs depending on their dose due to their various biological activities, e.g.…”

Identification of WRKY gene family and characterization of cold stress-responsive WRKY genes in eggplant

“…For instance, there are more than 70 WRKY proteins in Arabidopsis (Eulgem et al, 2000;Dong, Chen & Chen, 2003), 102 WRKY proteins in rice (Ross, Liu & She, 2007), 174 WRKY proteins in soybean (Glycine max L.) (Yang et al, 2017a;Yang et al, 2017b) and 81 WRKY proteins in tomato (Huang et al, 2012a;Huang et al, 2012b). Eggplant, a world-wide cultivated species, is one of the most important vegetable crops (Wang, Sulli & Fu, 2017;Yang et al, 2017a;Yang et al, 2017b). It is especially popular in Asia, the Middle and Near East, Southern Europe and Africa (Daunay & Lester, 1988).…”