Light-Induced Flavonoid Biosynthesis in Sinopodophyllum hexandrum with High-Altitude Adaptation

Abstract

Sinopodophyllum hexandrum is a perennial alpine herb producing the anti-cancer metabolite podophyllotoxin (PPT). Although the adaptation of S. hexandrum to high altitudes has been demonstrated and the effects of temperature, precipitation, and UV-B light on plant growth and metabolite accumulation have been studied, knowledge on the role of flavonoid biosynthesis in adapting to high altitudes is limited. In this study, light intensity, amount and type of flavonoids, and differentially expressed proteins (DEPs) and genes (DEGs) at 2300 and 3300 m were analyzed by HPLC, proteomic, transcriptomic, and qRT-PCR analysis. We found that higher light intensity correlated with greater flavonoid, flavonol, and anthocyanin content as well as higher anthocyanin to total flavonoid and flavonol ratios observed at the higher altitude. Based on proteomic and transcriptomic analyses, nine DEPs and 41 DEGs were identified to be involved in flavonoid biosynthesis and light response at 3300 m. The relative expression of nine genes (PAL, CHS1, IFRL, ANS, MYB4, BHLH137, CYP6, PPO1, and ABCB19) involved in flavonoid biosynthesis and seven genes (HSP18.1, HSP70, UBC4, ERF5, ERF9, APX3, and EX2) involved in light stress were observed to be up-regulated at 3300 m compared with 2300 m. These findings indicate that light intensity may play a regulatory role in enhancing flavonoid accumulation that allows S. hexandrum to adapt to elevated-altitude coupled with high light intensity.

Altitudinal variation of dragon fruit metabolite profiles as revealed by UPLC-MS/MS-based widely targeted metabolomics analysis

“…Particularly, Wang et al found that Lycium barbarum fruits from high-altitude locations in China had higher flavonoid content [ 14 ]. Furthermore, our results denote that climatic conditions at WM may stimulate signal transduction mechanisms in developing dragon fruits, leading to higher induction of flavonoid biosynthesis structural and regulatory genes’ expressions [ 51 ]. Flavonoids are the most diverse class of polyphenol secondary metabolites and the third largest class of natural products broadly distributed in the plant kingdom [ 52 ].…”

“…These findings are consistent with previous reports indicating an enhanced biosynthesis and accumulation of phenylpropanoid pathway-related compounds (flavonoid, anthocyanins, phenolic acids, etc.) in plants at high altitudes [ 16 , 17 , 49 , 51 ]. Particularly, Wang et al found that Lycium barbarum fruits from high-altitude locations in China had higher flavonoid content [ 14 ].…”

Transcriptome and metabolome analysis reveals mechanism of light intensity modulating iridoid biosynthesis in Gentiana macrophylla Pall.

“…The mechanism of photoregulation was also investigated. Higher altitude with strong light intensity increased the expression of genes involved in light stress ( HSP18.1 , HSP70 , UBC4 , ERF5 , ERF9 , APX3 and EX2 ) and genes involved in flavonoid biosynthesis ( PAL , CHS1 , IFRL , ANS , MYB4 , bHLH137 , CYP6 , PPO1 and ABCB19 ), thus promoting the accumulation of flavonoids, flavonols, and anthocyanins in Sinopodophyllum hexandrum [ 22 ]. Three key genes in the anthocyanin biosynthesis pathway ( CHI , DFR , and ANS ) and 147 transcription factors (MYB, bHLH, bZIP, ERF, and NAC) involved in malonylshisonin biosynthesis were identified [ 15 ].…”