EkFLS overexpression promotes flavonoid accumulation and abiotic stress tolerance in plant

Abstract

Flavonoids with great medicinal value play an important role in plant individual growth and stress resistance. Flavonol synthetase (FLS) is one of the key enzymes to synthesize flavonoids. However, the role of the FLS gene in flavonoid accumulation and tolerance to abiotic stresses, as well as its mechanism has not yet been investigated systematically in plants. The aim of this research is to evaluate the effect of FLS overexpression on the accumulation of active ingredients and stress resistance inEuphorbia kansui Liou. The results showed that when the EkFLS gene was overexpressed in Arabidopsis thaliana, the accumulation of flavonoids was improved. In addition, when the wild-type and EkFLS overexpressed Arabidopsis plants were treated with ABA and MeJA, compared with WT Arabidopsis, EkFLS overexpressed Arabidopsis promoted stomatal aperture to influence photosynthesis of the plants, which in turn can promote stress resistance. Meanwhile, under MeJA, NaCl, and PEG treatment, EkFLS overexpressed in Arabidopsis induced higher accumulation of flavonoids, which significantly enhanced peroxidase (POD) and superoxide dismutase (SOD) activities that can scavenge reactive oxygen species in cells to protect the plant. These results indicated that EkFLS overexpression is strongly correlated to the increase of flavonoid synthesis and therefore the tolerance to abiotic stresses in plants, providing a theoretical basis for further improving the quality of medicinal plants and their resistance to abiotic stresses simultaneously.

Molecular Cloning and Analysis of an Acetyl-CoA C-acetyltransferase Gene (EkAACT) from Euphorbia kansui Liou

“…Moreover, compared with WT, the AtSOD and AtPOD enzyme activities of L2, L3, and L6 transgenic plants increased by approximately 19.91% and 15.28% under NaCl stress, and increased by approximately 19.20% and 8.48% under PEG stress, respectively (Figure 9c,d). On the other hand, proline accumulation was used as a physiological index of water shortage in plants [33]. Under NaCl and PEG treatment, the increase in free proline in vivo EkAACT-overexpressing Arabidopsis was lower than that in WT plants (Figure 10), which indicated that EkAACT-overexpressing Arabidopsis has a high-water content.…”

“…Previous studies demonstrated that plants can activate a series of complex signal transmission networks to resist abiotic stress. This activation can improve tolerance to NaCl and drought stress by increasing SOD and POD enzyme activity to remove excess intracellular reactive oxygen species (ROS), which can inhibit ROS-induced intracellular component oxidation and damage [32,33]. The gene expression and enzyme activity of SOD and POD were measured to investigate whether EkAACT-overexpressing Arabidopsis can promote plant stress resistance to NaCl and drought.…”

“…Proline is proposed to act as the main osmolyte in enhancing plant stress tolerance [34]. Proline accumulation is used as a physiological index of water shortage in plants, which increased with the decrease in the water content in plants [33]. Under NaCl and PEG treatment, the proline content of EkAACT transgenic Arabidopsis (L6) and wild-type plants was measured.…”

“…Both wild-type Arabidopsis thaliana (Arabidopsis, Brassicaceae) and EkAACT-overexpressing transgenic lines were derived from the Columbia (Col-0) ecotype. After surface sterilization with 75% (v/v) ethyl alcohol and 10% (v/v) HClO, the seeds were sown on 1/2 Murashige and Skoog (MS) medium supplemented with 2% (w/v) sucrose and 0.7% (w/v) agar [33] and grown in a 22 • C light incubator for 10 days. Then, the seedlings were potted in soil and grown in a greenhouse at 22 • C under a 16 h light/8 h dark illumination regime as previously described [53,54].…”

“…The four-week-old WT and transgenic OEAACT-2, OEAACT-3, and OEAACT-6 Arabidopsis lines were irrigated using 200 mM NaCl and 20% PEG once every four days for two weeks [33]. Assays of gene expression levels and total triterpenoid contents in transgenic Arabidopsis were performed as described above.…”