G2-LIKE CAROTENOID REGULATOR (SlGCR) is a positive regulator of lutein biosynthesis in tomato

Abstract

Lutein is an oxygen-containing carotenoid synthesized in plant chloroplasts and chromoplasts. It plays an indispensable role in promoting plant growth and maintaining eye health in humans. The rate-limiting step of lutein biosynthesis is catalyzed by the lycopene ε-cyclase enzyme (LCYE). Although great progress has been made in the identification of transcription factors involved in the lutein biosynthetic pathway, many systematic molecular mechanisms remain to be elucidated. Here, using co-expression analysis, we identified a gene, G2-LIKE CAROTENOID REGULATOR (SlGCR), encoding a GARP G2-like transcription factor, as the potential regulator of SlLCYE in tomato. Silencing of SlGCR reduced the expression of carotenoid biosynthetic genes and the accumulation of carotenoids in tomato leaves. By contrast, overexpression of SlGCR in tomato fruit significantly increased the expression of relevant genes and enhanced the accumulation of carotenoids. SlGCR can directly bind to the SlLCYE promoter and activate its expression. In addition, we also discovered that expression of SlGCR was negatively regulated by the master regulator SlRIN, thereby inhibiting lutein synthesis during tomato fruit ripening. Taken together, we identified SlGCR as a novel regulator involved in tomato lutein biosynthesis, elucidated the regulatory mechanism, and provided a potential tool for tomato lutein metabolic engineering.

SlERF.G3‐Like mediates a hierarchical transcriptional cascade to regulate ripening and metabolic changes in tomato fruit

“…For instance, our previous studies indicate that SlRIN can directly activate the expression of SlWRKY35 , an inducer of SlDXS1 , to guide carbon flux towards the MEP pathway and enhance downstream carotenoid biosynthesis (Yuan et al ., 2022 ). In the meantime, SlRIN can also inhibit the expression of SlGCR , an inducer of SlLCYE , to suppress the production of lutein from the main carotenoid pathway (Ren et al ., 2022 ). Together, the SlRIN‐WRKY35 and SlRIN‐SlGCR modules accurately regulate the significant induction of carotenoid biosynthesis during tomato ripening.…”

Involvement of Transcription Factors and Regulatory Proteins in the Regulation of Carotenoid Accumulation in Plants and Algae

“…Overexpression of the AcGLK gene in tomato could significantly increase the number and size of chloroplasts, the accumulation of chlorophyll, carotenoids, and sugar, and improve the photosynthetic efficiency and nutritional quality of tomato . Tomato GLK transcription factor SlGCR could bind to the AGATT cis -acting element on the promoter of SlLCYe , thereby promoting the accumulation of lutein . It was also found that Arabidopsis AtGLK1/2 could form regulatory modules by interacting with G-box binding factors (GBFs) and then bind to G-box elements of the PSY promoter, thereby regulating photosynthetic pigment synthesis and affecting carotenoid accumulation .…”

“…Golden2-like (G2-like, GLK) transcription factor belongs to the GARP transcription factor and is a key transcription factor related to photosynthesis regulation in plants, which can regulate photosynthesis by activating genes related to photosynthesis, chloroplast development, and chlorophyll metabolism. , In recent years, GLK transcription factors have been found to be involved in the regulation of carotenoid metabolism (Table ). Overexpression of the AcGLK gene in tomato could significantly increase the number and size of chloroplasts, the accumulation of chlorophyll, carotenoids, and sugar, and improve the photosynthetic efficiency and nutritional quality of tomato .…”

“…82 Tomato GLK transcription factor SlGCR could bind to the AGATT cis-acting element on the promoter of SlLCYe, thereby promoting the accumulation of lutein. 81 It was also found that Arabidopsis AtGLK1/2 could form regulatory modules by interacting with G-box binding factors (GBFs) and then bind to G-box elements of the PSY promoter, thereby regulating photosynthetic pigment synthesis and affecting carotenoid accumulation. 83 Taken together, it is suggested that GLK transcription factors can participate in the regulation of photosynthesis and pigment metabolism, thus affecting photosynthetic efficiency and carotenoid accumulation, and can affect the photosynthetic efficiency and the nutritional quality of crops.…”

EpMYB2 positively regulates chicoric acid biosynthesis by activating both primary and specialized metabolic genes in purple coneflower

“…Co-expression analysis among metabolites, structural genes, and TFs has been widely used for the identification of intermediate substrates, biosynthetic genes, and regulators (Fu et al, 2022;Hong et al, 2022;Jin et al, 2024;Li et al, 2020;Reed et al, 2023;Ren et al, 2022;Yuan et al, 2022). We then used the six highly correlated chicoric acid biosynthetic genes as baits for co-expression analysis.…”