Comparative transcriptome profiling of different tissues from beta-carotene-enhanced transgenic soybean and its non-transgenic counterpart

Abstract

Beta-carotene-enhanced transgenic soybeans, harboring genes encoding phytoene synthase and carotene desaturase under the control of a seed-specific promoter, were developed to alleviate vitamin A deficiency in populations, the diet of which was deficient in this vitamin. However, metabolic engineering of carotenoid biosynthetic pathways often has unintended effects, leading to major metabolic changes in plants that harbor endogenous beta-carotene biosynthesis pathways. In the present study, we performed transcriptome profiling analysis using RNA-seq to investigate the changes in the transcriptome and some unintended pleiotropic effects on the leaves, stems, roots, and seeds of beta-carotene-enhanced transgenic soybean lines, and compared them to those of their non-transgenic counterpart donor variety Kwangan. We observed that transgenic soybeans showed significant changes in secondary metabolic biosynthesis in leaves and down-regulated galactose metabolism in roots. Differentially expressed genes in the transgenic group, which were significantly up-regulated, included those encoding glycine-aspartic acid-serine-leucine-motif esterase/lipase, known as cutin synthase and cutinase. These results suggested enhanced beta-carotene biosynthesis may affect related enzymes to carbohydrate metabolism and fatty acid metabolism. Hence, we speculated that upregulation of cutin polymerization resulted in thickened seed coat and delayed seed germination of transgenic soybeans. Furthermore, downregulation of raffinose family oligosaccharide biosynthesis may cause redundancy of myo-inositol, a substrate of phytin formation. This could lead to phytic globoids accumulation in transgenic soybean seeds. The present imformation would be important for transgenic plant development via carotenoid metabolic engineering, with focus on beta-carotene overproduction. Key message Gene expression changes related to secondary metabolite biosynthesis, cutin metabolism, and raffinose-family oligosaccharide biosynthesis in leaf, stem, and root, and phytin globoid accumulation in seeds, occurred in beta-carotene-enhanced transgenic soybeans.

Inhibition of Carotenoid Biosynthesis by CRISPR/Cas9 Triggers Cell Wall Remodelling in Carrot

“…Additionally, the overexpression of LCYb gene in tomato resulted in the enhanced metabolism of lycopene to β-carotene and in the increase of ABA content what was linked with extended fruit shelf life [ 9 ]. Gene ontology analysis revealed that several genes involved in cell wall organisation and hydrolase activity of O -glycosyl compounds were upregulated also in soybean containing the insertion of psy overexpressing construct [ 10 ]. The yellow-fruited tomato 1 ( yft1 ) mutant, which fruit contained only 6% of the total carotenoids of that of the wild type cultivar, had delayed chromoplast development and a modified cell wall composition [ 69 , 70 ].…”

“…However, we showed for the first time that alterations in carotenoid biosynthesis are related to cell wall remodelling, which was visualised directly in the cell walls with the use of immunohistochemistry method. Furthermore, some changes in gene expression and protein synthesis in soybean that were connected to carotenoid biosynthesis were detected for fascilin-like AGP [ 10 ]. Our study presents another data that indicate a correlation between AGPs presence and carotene biosynthesis.…”

“…In recent years, there has been an increasing amount of data suggesting a relationship between the biosynthesis of carotenoids and the chemical composition of the cell wall. The available data indicate that the overexpression or disturbance in the expression of carotenoid genes affects, among others, the expression of genes that take part and regulate the biosynthesis of cell wall components [ 9 , 10 , 11 ]. Moreover, strigolactones may participate in the secondary wall architecture remodelling [ 12 ].…”

The functions and applications of GDSL esterase/lipase proteins in agriculture: A review

“…67 Recently, a comparative transcriptomic profiling showed enriched transcripts of six GELPs in selected β-carotene-enhanced soybean stems, leaves, and seeds. 68 The exact mechanism of why these GELPs are overproduced in this transgenic soybean still remains unknown.…”

“…This variety was created from modified Kwangan variety soybean to produce higher amounts of β‐carotene, a precursor of vitamin A 67 . Recently, a comparative transcriptomic profiling showed enriched transcripts of six GELP s in selected β‐carotene‐enhanced soybean stems, leaves, and seeds 68 . The exact mechanism of why these GELPs are overproduced in this transgenic soybean still remains unknown.…”