Physiological factors affecting transcription of genes involved in the flavonoid biosynthetic pathway in different rice varieties

Abstract

Flavonoids play an important role in the grain color and flavor of rice. Since their characterization in maize, the flavonoid biosynthetic genes have been extensively studied in grape, Arabidopsis, and Petunia. However, we are still a long way from understanding the molecular features and mechanisms underlying the flavonoid biosynthetic pathway. The present study was undertaken to understand the physiological factors affecting the transcription and regulation of these genes. We report that the expression of CHI, CHS, DFR, LAR, and ANS, the 5 flavonoid biosynthetic genes in different rice varieties, differ dramatically with respect to the stage of development, white light, and sugar concentrations. We further demonstrate that white light could induce the transcription of the entire flavonoid biosynthetic gene pathway; however, differences were observed in the degrees of sensitivity and the required illumination time. Our study provides valuable insights into understanding the regulation of the flavonoid biosynthetic pathway.

Transcriptome and Proteome Profiling of Different Colored Rice Reveals Physiological Dynamics Involved in the Flavonoid Pathway

“…Our study showed that transcription factors did not differ significantly in expression among the different rice cultivars, whereas the downstream genes involved in the flavonoid biosynthesis pathway showed significant differences. This corroborates with an earlier report by Chen [19]. Therefore, it is reasonable to conclude that while transcription factors regulate flavonoid biosynthesis, the differences in contents and types of flavonoids among the different pigmented rice cultivars are due to changes in sequence differences, including the promoter region, UTR, and conserved domain of key genes involved in flavonoid biosynthesis.…”

“…Additionally, for metabolic enzymes and proteins involved in photosynthesis and anthocyanin biosynthesis, sugar is a common regulator [32]. It has been shown that sucrose induces anthocyanin accumulation and increases the expression of DFR, ANS, and LAR in rice and Arabidopsis [19,33].…”

“…One of the main functions of flavonoids is to attenuate effects caused by ROS [35,36]. In pigmented rice, the antioxidant capacity of the caryopsis is mainly derived from the pericarp, while very few differences exist in the endosperm compared to white rice [19]. This antioxidant effect is mainly derived from flavonoid synthesis.…”

“…These transcription factors belong to multigenic families encompassing 162 members in Arabidopsis and 167 members in rice, and several of them participate in regulation of flavonoid biosynthesis [14,15,16]. There are also other factors that affect the regulation of flavonoid biosynthesis, including light and sugar [17,18,19]. Additionally, several genes are involved in photosynthesis, but only some of these genes participate in the regulation of flavonoid biosynthesis; for example, among dicotyledonous species, flavone formation is primarily catalyzed by CYP93B enzymes [20].…”

Black rice cultivar from Java Island of Indonesia revealed genomic, proteomic, and anthocyanin nutritional value

“…Anthocyanins are influenced by several environmental factors and regulated by genetic variability and transcription factors (Chin et al, 2016;Zheng et al, 2019). Genes related to anthocyanins' production that have been well studied include structural genes encoding the enzymes: phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), chalcone isomerase (CHI), anthocyanin synthase (ANS), flavonol-3-hydroxylase (F3H), dihydroflavonol reductase (DFR), and anthocyanin reductase (ANR) (Chen et al, 2013). Furthermore, these anthocyanin synthesis genes are regulated by several transcription factors, such as MYB, MYC, Rc, and C-S-A (Himi & Taketa, 2015).…”