TRANSPARENT TESTA 4‐mediated flavonoids negatively affect embryonic fatty acid biosynthesis in Arabidopsis

Abstract

Flavonoids are involved in many physiological processes in plants. TRANSPARENT TESTA 4 (TT4) acts at the first step of flavonoid biosynthesis, and the loss of TT4 function causes a lack of flavonoid. Flavonoid deficiency is reportedly the main cause of increased fatty acid content in pale-coloured oilseeds, but details regarding the relationship between seed flavonoids and fatty acid biosynthesis are elusive. In this work, we applied a genetic strategy combined with biochemical and cytological assays to determine the effect of seed flavonoids on the biosynthesis of fatty acids in Arabidopsis thaliana. We showed that TT4-mediated flavonoids negatively affect embryonic fatty acid biosynthesis. A crossing experiment indicated that seed flavonoid biosynthesis and the impact of this process on fatty acid biosynthesis were controlled in a maternal line-dependent manner. Loss of TT4 function activated glycolysis in seed embryos, thereby enhancing fatty acid biosynthesis, but did not improve seed mucilage production. Moreover, loss of TT4 function reduced PIN-FORMED 4 expression and subsequently increased auxin accumulation in embryos. Pharmacologically and genetically elevated auxin levels enhanced seed fatty acid biosynthesis. These results indicated that flavonoids affect fatty acid biosynthesis by carbon source reallocation via regulation of WRINKLE1 and auxin transport.

Exogenous abscisic acid induces on lipid and flavonoid metabolism of tea plant under drought stress

“…The results showed that the expressions of CHI (CSA026735) and DFR (CSA003949) were significantly positive correlation with apigenin O-malonylhexoside, delphinidin 3-O-glucoside, gallocatechin and dihydromyricetin, while the expression of 4CL (CSA007753) was significantly negative correlation with apigenin O-malonylhexoside and delphinidin 3-O-glucoside, suggesting that the exogenous ABA could induce the expressions of genes involved in flavonoid biosynthesis, and hence affected the biosynthesis of flavonoids and derivatives of tea leaves under drought stress.Moreover, previous research showed that inhibition of lipid synthesis redirects the carbon flux into flavonoid metabolism[36]. Recently, CHS-mediated flavonoids were proven to repress embryonic fatty acid biosynthesis in the Arabidopsis seeds, implying a negative correlation between flavonoids and fatty acids biosynthesis in plants[37]. Our results showed that the exogenous ABA drastically decreased the abundances of lipid metabolites and increased the abundances of most flavonoids compared with severe drought.…”

Melatonin Represses Oil and Anthocyanin Accumulation in Seeds

“…2, B, C, E, and F), suggest that melatonin is an important player in the regulatory network that represses the accumulation of both oil and anthocyanins in Arabidopsis seeds. Several previous studies showed a negative correlation between the contents of oil and flavonoids in Arabidopsis seeds (Chen et al, 2012b(Chen et al, , 2014(Chen et al, , 2015Li et al, 2018a;Xuan et al, 2018). Thus, it is generally considered difficult for breeders to synergistically improve both seed oil and flavonoid contents.…”

Plant Unsaturated Fatty Acids: Biosynthesis and Regulation

“…FA synthesis is then enhanced at least partially due to increased carbon allocation (Li et al, 2018), as occurs upon deficiency of TT4, the chalcone synthase for flavonoid biogenesis. In the tt4 mutant, WRI1 and its downstream genes involved in glycolysis and FA synthesis are activated, thus driving the reorientated sugar source into the two pathways (Xuan et al, 2018).…”