The Effect of Light Intensity on the Expression of Leucoanthocyanidin Reductase in Grapevine Calluses and Analysis of Its Promoter Activity

Abstract

To investigate the effect of light intensity on flavonoid biosynthesis, grapevine calluses were subjected to high light (HL, 250 μmol m−2 s−1) and dark (0 μmol m−2 s−1) in comparison to 125 μmol m−2 s−1 under controlled conditions (NL). The alteration of flavonoid profiles was determined and was integrated with RNA sequencing (RNA-seq)-based transcriptional changes of the flavonoid pathway genes. Results revealed that dark conditions inhibited flavonoid biosynthesis. Increasing light intensity affected flavonoids differently—the concentrations of flavonols and anthocyanins as well as the expressions of corresponding genes were less affected, whereas flavan-3-ol concentrations were predominantly increased, which caused enhanced trans-flavan-3-ol concentrations. Moreover, genes encoding leucoanthocyanidin reductase (LAR) exhibited different response patterns to light intensity changes—VviLAR1 expression increased with an increased light intensity, whereas VviLAR2 expression was insensitive. We further confirmed that the known transcription factors (TFs) involved in regulating flavan-3-ol biosynthesis utilized VviLAR1 as a target gene in grapevine calluses. In addition, VviLAR1 promoter activity was more sensitive to light intensity changes than that of VviLAR2 as determined using a transgenic Arabidopsis leaf system. These results suggested that light intensity had the most prominent effect on trans-flavan-3-ols in grapevine calluses and demonstrated that the two LAR genes had different response patterns to light intensity changes.

Transcription Factor VviMYB86 Oppositely Regulates Proanthocyanidin and Anthocyanin Biosynthesis in Grape Berries

“…Recently, by calculating the correlations between the expression levels of structural and regulatory genes in the PA biosynthesis branch of grapevine calluses subjected to different light intensities, researchers showed that VviLAR2 was the target gene of VviMYBPA2. However, owing to the low expression level of VviMYBPA2 , the effects on the expression level of VviLAR2 are limited ( Cheng et al, 2020 ).…”

Transcription factor VvibHLH93 negatively regulates proanthocyanidin biosynthesis in grapevine

“…Our previous studies show that the promoter of VviLAR1 contains multiple E/G box elements, which are supposed to be the motifs for bHLH transcription factor recognition (Cheng et al, 2020(Cheng et al, , 2021. However, bHLH proteins that directly regulate VviLAR1 remain unknown.…”

“…The expression of VviLAR1 is restricted in flowers, young berries, and seeds, while VviLAR2 transcript is mainly detected in berry skins before veraison, seeds during veraison, and expending leaves (Bogs et al, 2005). In addition, previous studies show that the expression of VviLAR1 and VviANR is light-inducible, whereas the promoter activity of VviLAR2 is not sensitive to the change of light intensity (Koyama et al, 2012;Sun et al, , 2019Cheng et al, 2020). The above findings imply that different regulation mechanisms are underlying the expression of the three PA-specific genes in grapevine.…”

“…In grapevine, at least 119 bHLH family proteins have been identified based on the genome sequence ( Jaillon et al, 2007 ; Velasco et al, 2007 ), but only VviMYC1 and VviMYCA1 are shown to be associated with PA accumulation ( Hichri et al, 2010 ; Matus et al, 2010 ). Until now, bHLH transcription factors that regulate VviLARs remain unknown, although E/G boxes are rich in VviLAR1 promoter ( Cheng et al, 2020 , 2021 ).…”

Neuroprotective Effect and Antioxidant Potency of Fermented Cultured Wild Ginseng Root Extracts of Panax ginseng C.A. Meyer in Mice

“…Tissue culture technology, one of the technologies of plant production, enables the differentiation of cells into tissues or organs by the totipotency of plants, therefore it is at the center of researches into plant systems capable of producing specific metabolic products. Through cells and callus suspension culture, it has the advantages of genetic and biochemical stability, hormone autotrophy, and multienzyme biosynthetic capacity, etc., as a biocatalyst [ 47 , 48 ]. The synthesis of metabolites and biotransformation by an “elicitor” can bring about changes in subjects for research in substances originating from plants, which are realistically unavailable.…”