Ethylene Induced a High Accumulation of Dietary Isoflavones and Expression of Isoflavonoid Biosynthetic Genes in Soybean (Glycine max) Leaves

Abstract

Dietary isoflavones, daidzein and genistein are of huge interest in the nutraceutical field due to their practical application to postmenopause complications. This study is the first report an efficient method to prepare isoflavone rich soybean leaves (soyleaves) which is an edible food stuff in Asian countries. The preharvest treatment of ethylene highly stimulated the level of isoflavone in soyleaves. Annotation and quantification of metabolites were determined by UPLC-Q-TOF-MS and HPLC. Phenolic metabolites of soyleaves are mostly kaempferol glycosides, but not dietary isoflavones. The accumulated isoflavones by ethylene treatment were determined to be daidzin 1, genistin 2, malonyldaidzin 3 and malonylgenistin 4, which were easily hydrolyzed to daidzein and genistein by β-glucosidase. Total content of dietary isoflavones was increased up to 13854 μg/g. The most suitable condition was estimated to be 250 μg/g ethylene or 200 μg/g ethephon (ethylene donor) treatment at the R3 growth stage. The ratio of daidzein and genistein glycosides was approximately 5 to 3. The accumulated isoflavonoid biosynthesis pathway genes were identified within the transcriptome of soyleaves tissues at 1 day after treatment of ethephon. The quantitative RT-PCR analysis of these genes indicated significantly higher expression of CHS, CHI, IFS, HID, IF7GT, and IF7MaT compared to control leaves. These findings suggest that ethylene activates a set of structural genes involved in isoflavonoid biosynthesis, thereby leading to enhanced production of isoflavones in soybean plants.

A Multi‐Omics Analysis of Glycine max Leaves Reveals Alteration in Flavonoid and Isoflavonoid Metabolism Upon Ethylene and Abscisic Acid Treatment

“…Peak detection was performed at 254 nm. The four isoflavones were identified as per the retention time, and their concentrations were calculated by comparing the peak areas of the samples with those of the standards using LCSolutions software (Shimadzu, Kyoto, Japan) …”

SolarUV‐Bradiation and ethylene play a key role in modulating effective defenses againstAnticarsia gemmatalislarvae in field‐grown soybean

“…Because flavonols were not synergistically induced by the combination of herbivory and solar UV‐B radiation or after ACC application, our results suggest that only isoflavonoids are induced by ET alone (Figures , and ; Figures S3 and S4). Recently, a study have shown that both ethephon and ET induced isoflavonoids in potted soybean grown in a greenhouse (Yuk et al, ), suggesting the primary role of ET in the induction of certain defenses.…”

“…Also, ET applied exogenously or produced during pathogen infection or stink bug attack eliminates the JA‐SA antagonistic relationship, allowing the induction of both JA‐ and SA‐regulated defenses (Giacometti et al, ; Leon‐Reyes et al, ). Although few studies have focused on the effects of ET alone on plant defenses, recently, it has been suggested that ET can increase the production of isoflavonoids in soybean leaves (Yuk et al, ). Because it is not clear how solar UV‐B radiation synergistically increases chemical defenses in damaged leaves, we proposed that UV‐B radiation induces ET emission that increases the production of phenolic compounds and TPI in soybean leaves.…”

De novo transcriptomic analysis of light-induced flavonoid pathway, transcription factors in the flower buds of Lonicera japonica

“…Moreover, Jiao et al (1987) found that light reduces ethylene formation. Yuk et al (2016) suggested that ethylene activates a set of structural genes involved in flavonoid biosynthesis. Here, we identified a total of 120 ERF TFs, representing the largest TF family in our transcriptome data.…”