Identification of a Unique Type of Isoflavone O-Methyltransferase, GmIOMT1, Based on Multi-Omics Analysis of Soybean under Biotic Stress

Abstract

Isoflavonoids are commonly found in leguminous plants. Glycitein is one of the isoflavones produced by soybean. The genes encoding the enzymes in isoflavone biosynthetic pathway have mostly been identified and characterized. However, the gene(s) for isoflavone O-methyltransferase (IOMT), which catalyses the last step of glycitein biosynthesis, has not yet been identified. In this study, we conducted multi-omics analyses of fungal-inoculated soybean and indicated that glycitein biosynthesis was induced in response to biotic stress. Moreover, we identified a unique type of IOMT which participates in glycitein biosynthesis. Soybean seedlings were inoculated with Aspergillus oryzae or Rhizopus oligosporus and sampled daily for 8 days. Multi-omics analyses were conducted using liquid chromatography-tandem mass spectrometry and RNA sequencing. Metabolome analysis revealed that glycitein derivatives increased following fungal inoculation. Transcriptome co-expression analysis identified two candidate IOMTs that were co-expressed with the gene encoding flavonoid 6-hydroxylase (F6H), the key enzyme in glycitein biosynthesis. The enzymatic assay of the two IOMTs using respective recombinant proteins showed that one IOMT, named as GmIOMT1, produced glycitein. Unlike other IOMTs, GmIOMT1 belongs to the cation-dependent OMT family and exhibited the highest activity with Zn2+ among cations tested. Moreover, we demonstrated that GmIOMT1 overexpression increased the levels of glycitein derivatives in soybean hairy roots when F6H was co-expressed. These results strongly suggest that GmIOMT1 participates in inducing glycitein biosynthesis in response to biotic stress.

Identification and characterization of glycosyltransferases catalyzing direct xanthone 4‐C‐glycosylation in Hypericum perforatum

“…for 24 h. Cells were collected by centrifugation and disrupted using glass beads and LongLife PE LB Lysozyme (Geno Technology, St. Louis, MO, USA). The supernatant was collected by centrifugation, and the recombinant protein was purified using Profinia protein purification system (Bio‐Rad Laboratories, Hercules, CA, USA) as described previously [18].…”

“…The details of the sequences are listed in Table S2. A phylogenetic tree was created as described previously [18].…”

“…β‐Tubulin that shows low expression variation among plant organs [19] was used as a reference gene for real‐time PCR. Real‐time PCR was carried out using a primer set (Table S1) as described previously [18].…”

Study of Triticum aestivum Resistome in Response to Wheat dwarf India Virus Infection

“…O-methyltransferases (OMTs) are an essential group of enzymes that catalyze the transfer of a methyl group from S-adenosyl-L-methionine to their acceptor substrates and have been reported to play roles in abiotic and biotic stress tolerance [42][43][44]. Interestingly, one putative transcript for O-methyltransferase was highly upregulated (Ta.14545.1.S1_at) and one was downregulated (Ta.25173.1.S1_at) in Sonalika (Figure 9), suggesting a role in virus resistance.…”

Metabolomics Intervention Towards Better Understanding of Plant Traits

“…spp., Citrus spp., Lotus sp., Lupinus albus, Helianthus annuus L., Mangifera indica, Medicago trancatula, Malus spp., Fragaria × ananassa, Glycine max, Oryza sativa, Pyrus communis, Solanum lycopersicum L., Vitis vinifera, Zea mays, etc., [1,4]. The metabolomics study was done to explore multiple areas such as biotic stress [1,5,6], abiotic stress [7][8][9], legumes and cereals quality improvement [10][11][12][13][14][15][16][17], biofuel production and lipid profiling [18][19][20][21], impact of climate change and high CO 2 level [22][23][24][25], hormone profiling [26], and improving fruit quality [1,[26][27][28][29]. These attempts have provided opportunities to dissect the metabolic pathways for developing stress-tolerant and nutrition-rich crop plants [1].…”