Efficacy and Postoperative Outcomes of Laparoscopic Retrosternal Route Creation for the Gastric Conduit: Propensity Score-Matched Comparison to Posterior Mediastinal Reconstruction.

BACKGROUND: Retrosternal reconstruction has lower risks for severe postoperative morbidities, such as gastro-tracheal fistula or esophageal hiatal hernia. We have previously reported the laparoscopic retrosternal route creation (LRRC) method, but its safety and efficacy remain unclear. METHODS: In total, 374 patients with esophageal carcinoma who underwent minimally invasive McKeown esophagectomy in the prone position between 2010 and 2021 were retrospectively reviewed. We performed a propensity score-matched analysis with the simple, nearest-neighbor method and no calipers to compare postoperative outcomes and reconstructed gastric conduit functionality between patients who underwent LRRC and counterparts who underwent posterior mediastinal reconstruction. RESULTS: After matching, 62 patients were included in the laparoscopic retrosternal group (LR group) or posterior mediastinal group (PM group). No significant differences were observed between the groups, apart from the number of robot-assisted surgeries, the extent of lymph node dissection, and the method of cervical anastomosis. There were no significant differences in the incidence of Clavien-Dindo grade ≥ 2 complications. Gastro-tracheal fistula (n = 1) and esophageal hiatal hernia (n = 2) occurred in the PM group but not in the LR group. There were no differences in the incidence of pulmonary embolism between the groups (5% vs. 5%). The postoperative anastomotic stenosis rate was similar (16% vs. 27%, p = 0.192). Endoscopic findings of reflux esophagitis (modified Los Angeles classification ≥ M) at 1 year after surgery were significantly better in the LR group (p = 0.037). CONCLUSIONS: LRRC for gastric conduit reconstruction is safe and valuable. It is associated with good reconstructed gastric conduit function.

Albumin and Derived Neutrophil-to-Lymphocyte Ratio is a Novel Prognostic Factor for Patients with Esophageal Squamous Cell Carcinoma.

BACKGROUND: Multidisciplinary treatment combining neoadjuvant treatment (NAT) and surgery has slightly improved the prognosis of patients with esophageal squamous cell carcinoma (ESCC). Although various biomarkers targeting nutrition and inflammation are associated with cancer prognosis, most studies have focused on conditions prior to NAT. Developing real-time and sensitive biomarkers that monitor changes in systemic conditions during NAT is important. We established a novel nutritional and inflammatory index, represented as the albumin to derived neutrophil-to-lymphocyte ratio (Alb-dNLR), and calculated the change in Alb-dNLR (ΔAlb-dNLR) during neoadjuvant chemotherapy (nCT). In this study, we aimed to evaluate whether ΔAlb-dNLR is associated with prognosis in patients with ESCC. METHODS: We investigated 172 patients who underwent nCT before esophagectomy between April 2010 and March 2018. The dNLR was calculated as the ratio of neutrophil count to (white blood cell count - neutrophil count), Alb-dNLR was calculated by dividing the serum albumin level by the dNLR, and ΔAlb-dNLR was evaluated by dividing the post-Alb-dNLR by the pre-Alb-dNLR. Patients were divided into 'high' and 'low' groups according to the ΔAlb-dNLR. RESULTS: Thirty-nine patients (22.7%) had a low ΔAlb-dNLR (≤ 0.8), and the 5-year overall survival (OS) rates in patients with low and high ΔAlb-dNLR were 38.1% and 53.6%, respectively (p = 0.0072). Multivariate analyses demonstrated that estimated blood loss (p = 0.044), pathological T stage (p = 0.0005), pathological N stage (p = 0.017), and ΔAlb-dNLR (p = 0.005) were independent prognostic factors for OS. CONCLUSIONS: ΔAlb-dNLR is a useful prognostic factor for OS in patients with ESCC receiving nCT.

Albumin-Derived NLR Score is a Novel Prognostic Marker for Esophageal Squamous Cell Carcinoma.

BACKGROUND: Multidisciplinary treatment for esophageal squamous cell carcinoma (ESCC) has improved outcomes, but the prognosis for ESCC remains poor. Nutritional and inflammatory indicators are reported to be associated with cancer prognosis. The combination of albumin and the derived neutrophil-to-lymphocyte ratio (Alb-dNLR) score was established to measure the immune system and nutritional status. The authors hypothesized that the Alb-dNLR score could be a new reliable prognostic factor for ESCC patients. METHODS: The study evaluated 269 patients who underwent esophagectomy between April 2010 and March 2018, including 185 patients who received neoadjuvant chemotherapy. The Alb-dNLR score was calculated using serum albumin and the dNLR. The dNLR was calculated as neutrophils to (leukocyte-neutrophil count). The cutoff values of the albumin and dNLR for overall survival (OS) were determined using the receiver operating characteristic curve. Patients were divided into "high" and "low" groups according to the Alb-dNLR score. RESULTS: A high Alb-dNLR score was found in 61 cases (22.7%). The 5-year OS was 34% in the high Alb-dNLR group and 66.2% in the low Alb-dNLR group (p < 0.0001). The 5-year cause-specific survival (CSS) was 51.5% in the high Alb-dNLR group and 74.7% in the low Alb-dNLR group (p < 0.0001). Multivariate analyses demonstrated that the Alb-dNLR score was an independent prognostic factor for OS (hazard ratio [HR], 2.198; 95% confidence interval [CI], 1.460-3.263; p = 0.0002) and CSS (HR, 1.733; 95% CI, 1.035-2.835; p = 0.0371). CONCLUSIONS: The Alb-dNLR score is an extremely useful, easy-to-use parameter to predict OS and CSS for ESCC patients.

Laparoscopic creation of a retrosternal route for gastric conduit reconstruction.

BACKGROUND: Retrosternal reconstruction is associated with a lower risk of mediastinitis, gastro-tracheal fistula, and hiatal hernia. Historically, traumatic manual creation of the retrosternal tunnel has been performed using one's fist. We report a novel and atraumatic laparoscopic procedure to create the retrosternal route. METHODS: We have laparoscopically created the retrosternal route in 25 thoracoscopic, mediastinoscopic, or robot-assisted minimally invasive esophagectomies since August 2019. Specifically, a peritoneal incision is started at the dorsal side of the xiphoid process. Through a 12-mm port inserted slightly to the right of and superior to the umbilical camera port, we dissect loose connective tissues from the caudal to the cranial side using behind the sternum and inside the internal thoracic vessels as landmarks. The time required to create the route was calculated. Then, the cumulative sum (CUSUM) method and the simple moving average of five cases were used to evaluate the learning curve of this novel procedure. Operative outcomes were analyzed according to the learning curve results and also compared with 25 cases of postmediastinal reconstruction counterparts. RESULTS: Twenty-five patients were divided into the early group (six patients) and late group (19 patients) based on the peak of the CUSUM chart. The time required for route creation was 28.5 min (median) in the early and 15 min in the late group, indicating a significant difference (P = 0.038). The overall incidence of pleural injury was 20% (5 of 25 patients), with no significant difference between the groups. There was no significant difference in the incidence of perioperative complications. Also, there were no significant differences in perioperative complications or gastric conduit functions 1 year after surgery between the retrosternal and the postmediastinal reconstruction. CONCLUSION: Laparoscopic creation of a retrosternal route for gastric conduit reconstruction is safe and feasible and has a short learning curve.

(+)-Sesamin-oxidising CYP92B14 shapes specialised lignan metabolism in sesame.

Sesamum spp. (sesame) are known to accumulate a variety of lignans in a lineage-specific manner. In cultivated sesame (Sesamum indicum), (+)-sesamin, (+)-sesamolin and (+)-sesaminol triglucoside are the three major lignans found richly in the seeds. A recent study demonstrated that SiCYP92B14 is a pivotal enzyme that allocates the substrate (+)-sesamin to two products, (+)-sesamolin and (+)-sesaminol, through multiple reaction schemes including oxidative rearrangement of α-oxy-substituted aryl groups (ORA). In contrast, it remains unclear whether (+)-sesamin in wild sesame undergoes oxidation reactions as in S. indicum and how, if at all, the ratio of the co-products is tailored at the molecular level. Here, we functionally characterised SrCYP92B14 as a SiCYP92B14 orthologue from a wild sesame, Sesamum radiatum, in which we revealed accumulation of the (+)-sesaminol derivatives (+)-sesangolin and its novel structural isomer (+)-7´-episesantalin. Intriguingly, SrCYP92B14 predominantly produced (+)-sesaminol either through ORA or direct oxidation on the aromatic ring, while a relatively low but detectable level of (+)-sesamolin was produced. Amino acid substitution analysis suggested that residues in the putative distal helix and the neighbouring heme propionate of CYP92B14 affect the ratios of its co-products. These data collectively show that the bimodal oxidation mechanism of (+)-sesamin might be widespread across Sesamum spp., and that CYP92B14 is likely to be a key enzyme in shaping the ratio of (+)-sesaminol- and (+)-sesamolin-derived lignans from the biochemical and evolutionary perspectives.

Glycoside-specific glycosyltransferases catalyze regio-selective sequential glucosylations for a sesame lignan, sesaminol triglucoside.

Sesame (Sesamum indicum) seeds contain a large number of lignans, phenylpropanoid-related plant specialized metabolites. (+)-Sesamin and (+)-sesamolin are major hydrophobic lignans, whereas (+)-sesaminol primarily accumulates as a water-soluble sesaminol triglucoside (STG) with a sugar chain branched via ß1→2 and ß1→6-O-glucosidic linkages [i.e. (+)-sesaminol 2-O-ß-d-glucosyl-(1→2)-O-ß-d-glucoside-(1→6)-O-ß-d-glucoside]. We previously reported that the 2-O-glucosylation of (+)-sesaminol aglycon and ß1→6-O-glucosylation of (+)-sesaminol 2-O-ß-d-glucoside (SMG) are mediated by UDP-sugar-dependent glucosyltransferases (UGT), UGT71A9 and UGT94D1, respectively. Here we identified a distinct UGT, UGT94AG1, that specifically catalyzes the ß1→2-O-glucosylation of SMG and (+)-sesaminol 2-O-ß-d-glucosyl-(1→6)-O-ß-d-glucoside [termed SDG(ß1→6)]. UGT94AG1 was phylogenetically related to glycoside-specific glycosyltransferases (GGTs) and co-ordinately expressed with UGT71A9 and UGT94D1 in the seeds. The role of UGT94AG1 in STG biosynthesis was further confirmed by identification of a STG-deficient sesame mutant that predominantly accumulates SDG(ß1→6) due to a destructive insertion in the coding sequence of UGT94AG1. We also identified UGT94AA2 as an alternative UGT potentially involved in sugar-sugar ß1→6-O-glucosylation, in addition to UGT94D1, during STG biosynthesis. Yeast two-hybrid assays showed that UGT71A9, UGT94AG1, and UGT94AA2 were found to interact with a membrane-associated P450 enzyme, CYP81Q1 (piperitol/sesamin synthase), suggesting that these UGTs are components of a membrane-bound metabolon for STG biosynthesis. A comparison of kinetic parameters of these UGTs further suggested that the main ß-O-glucosylation sequence of STG biosynthesis is ß1→2-O-glucosylation of SMG by UGT94AG1 followed by UGT94AA2-mediated ß1→6-O-glucosylation. These findings together establish the complete biosynthetic pathway of STG and shed light on the evolvability of regio-selectivity of sequential glucosylations catalyzed by GGTs.

Incidence of Recurrent Laryngeal Nerve Palsy in Robot-Assisted Versus Conventional Minimally Invasive McKeown Esophagectomy in Prone Position: A Propensity Score-Matched Study.

BACKGROUND: Esophagectomy with lymphadenectomy is the principal treatment for localized esophageal cancer. Conventional minimally invasive esophagectomy (C-MIE) in prone position has spread worldwide as it is less invasive. However, its efficacy remains controversial. Robot-assisted MIE (RAMIE) can have more advantages than C-MIE. Therefore, the current study aimed to validate whether RAMIE is associated with lower incidence of left recurrent laryngeal nerve (RLN) palsy compared with C-MIE in prone position. PATIENTS AND METHODS: In total, 404 patients with esophageal carcinoma underwent MIE (353 C-MIEs and 51 RAMIEs) in prone position at Kobe University between 2010 and 2020. Then, propensity score matching was performed, and results showed that 51 patients should be included in each group. Thereafter, the perioperative outcomes between the two groups were compared. RESULTS: The RAMIE group had a significantly longer operative time than the C-MIE group (P < 0.0001). However, the number of lymph nodes resected along the left RLN was similar in both groups. Moreover, the incidence of left RLN palsy was significantly lower in the RAMIE group than in the C-MIE [Clavien-Dindo classification grade II; 0 (0%) versus 32 (9%), P = 0.022 in entire cohort, and 0 (0%) versus 5 (10%), P = 0.022 in matched cohort. Esophagectomy Complications Consensus Group definitions type I; 8 (16%) versus 101 (29%), P = 0.041 in entire cohort and 8 (16%) versus 18 (35%) in matched cohort, P = 0.023]. CONCLUSION: RAMIE is superior to C-MIE in prone position in decreasing the incidence of left RLN palsy.

Distinguishing between isomeric neoxanthin and violaxanthin esters in yellow flower petals using liquid chromatography/photodiode array atmospheric pressure chemical ionization mass spectrometry and tandem mass spectrometry.

RATIONALE: Liquid chromatography/photodiode array atmospheric pressure chemical ionization mass spectrometry (LC/PDA-APCI-MS) is used for the analysis of various carotenoid pigments in plants. Among them, it is difficult to distinguish between the isomeric violaxanthin/neoxanthin esters. METHODS: The yellow pigments of tomato petals were extracted with acetone, and the extracts were kept at -30°C to allow the contaminating triacylglycerols to settle out physically. The supernatants were analyzed using LC/PDA-APCI-MS with a high-resolution orbitrap mass spectrometer for their exact masses. The expected carotenoid esters were calculated with the combination of carotenoids and fatty acids, and they were matched with the experimental exact masses. The fatty acid structures in the carotenoid esters were also identified using collision-induced dissociation (CID) tandem mass spectrometry (MS/MS). The isomeric violaxanthin/neoxanthin esters were distinguished using CID MS/MS from their in-source dehydrated product ions as pseudoprecursor ions. RESULTS: The in-source dehydrated ions [M - H2 O + H]+ of neoxanthin diesters predominated over their protonated molecules [M + H]+ in LC/MS. By contrast, the protonated molecules of violaxanthin diesters predominated. The 92 u loss product ions [M - H2 O - C7 H8 + H]+ were observed from the dehydrated violaxanthin diesters, but they were not generated from the dehydrated neoxanthin diesters in the CID MS/MS of their dehydrated pseudoprecursor ion [M - H2 O + H]+ . CONCLUSIONS: The allene allyl carbocation in neoxanthin diesters was generated from dehydration after preferential protonation at the hydroxy group. The epoxide group of violaxanthin diesters opens easily after protonation; however, the dehydration did not proceed at this stage. The 92 u loss of C7 H8 was explained by an intramolecular [2 + 2] cycloaddition, which proceeded preferentially in dehydrated violaxanthin diesters because the carbocations in the dehydrated species were conjugated to the polyene and those double bonds were depolarized during CID MS/MS. Therefore, the isomeric neoxanthin/violaxanthin diesters were distinguished using LC/PDA-APCI-MS and MS/MS. This method was a practical and useful method of profiling the carotenoid esters of the yellow petals.

Functional specialization of UDP-glycosyltransferase 73P12 in licorice to produce a sweet triterpenoid saponin, glycyrrhizin.

Glycyrrhizin, a sweet triterpenoid saponin found in the roots and stolons of Glycyrrhiza species (licorice), is an important active ingredient in traditional herbal medicine. We previously identified two cytochrome P450 monooxygenases, CYP88D6 and CYP72A154, that produce an aglycone of glycyrrhizin, glycyrrhetinic acid, in Glycyrrhiza uralensis. The sugar moiety of glycyrrhizin, which is composed of two glucuronic acids, makes it sweet and reduces its side-effects. Here, we report that UDP-glycosyltransferase (UGT) 73P12 catalyzes the second glucuronosylation as the final step of glycyrrhizin biosynthesis in G. uralensis; the UGT73P12 produced glycyrrhizin by transferring a glucuronosyl moiety of UDP-glucuronic acid to glycyrrhetinic acid 3-O-monoglucuronide. We also obtained a natural variant of UGT73P12 from a glycyrrhizin-deficient (83-555) strain of G. uralensis. The natural variant showed loss of specificity for UDP-glucuronic acid and resulted in the production of an alternative saponin, glucoglycyrrhizin. These results are consistent with the chemical phenotype of the 83-555 strain, and suggest the contribution of UGT73P12 to glycyrrhizin biosynthesis in planta. Furthermore, we identified Arg32 as the essential residue of UGT73P12 that provides high specificity for UDP-glucuronic acid. These results strongly suggest the existence of an electrostatic interaction between the positively charged Arg32 and the negatively charged carboxy group of UDP-glucuronic acid. The functional arginine residue and resultant specificity for UDP-glucuronic acid are unique to UGT73P12 in the UGT73P subfamily. Our findings demonstrate the functional specialization of UGT73P12 for glycyrrhizin biosynthesis during divergent evolution, and provide mechanistic insights into UDP-sugar selectivity for the rational engineering of sweet triterpenoid saponins.

[Brain Metastasis and Leptomeningeal Carcinomatosis after Surgery for Esophageal Cancer-A Case Report].

A 70-year-old man had undergone thoracoscopic esophagectomy following neoadjuvant chemotherapy for thoracic esophageal squamous cell carcinoma 3 years before presentation. He was undergoing whole-brain irradiation following surgery for a solitary brain metastatic tumor. The chief complaint was left leg pain during irradiation. FDG-PET/CT and MRI revealed metastases in bilateral cauda equina S1 nerve roots. Cerebrospinal fluid examination also revealed malignant cells. He received chemotherapy with 2 courses of 5-fluorouracil and cisplatin following 30 Gy of spinal irradiation. To control neurological symptoms, 4 courses of intrathecal chemotherapy with methotrexate, cytarabine, and betamethasone were performed. However, he gradually weakened and died 8 months after brain metastasis and 7 months after leptomeningeal carcinomatosis. The multidisciplinary treatment using irradiation and systemic and intrathecal chemotherapies could improve the survival of patients with leptomeningeal carcinomatosis of esophageal squamous cell carcinoma.

[Effect of Proteinuria in Patients Receiving Anti-VEGF Therapy for Advanced Colorectal Cancer].

Grade 2 or 3 proteinuria was observed in 54 patients out of 158 metastatic colorectal cancer patients receiving anti-VEGF therapy. Patients with diabetes and hypertension were risk for severe proteinuria. ARBs were more frequently used in patients with severe proteinuria. However, they could not reduce proteinuria. The examination of protein/creatinine ratio was useful for continuing anti-VEGF therapy.

Identification and Characterization of Novel Nemophila menziesii Flavone Glucosyltransferases that Catalyze Biosynthesis of Flavone 7,4'-O-Diglucoside, a Key Component of Blue Metalloanthocyanins.

The brilliant blue color of the Nemophila menziesii flower is derived from metalloanthocyanin, which consists of anthocyanin {petunidin 3-O-[6-O-(trans-p-coumaroyl)-ß-glucoside]-5-O-[6-O-(malonyl)-ß-glucoside]}, flavone [apigenin 7-O-ß-glucoside-4'-O-(6-O-malonyl)-O-ß-glucoside] and metal ions (Mg2+, Fe3+). Although the two glucosyl moieties at the apigenin 7-O and 4'-O positions are essential for metalloanthocyanin formation, the mechanism of glucosylation has not yet been clarified. In this study, we used crude protein extract prepared from N. menziesii petals to determine that apigenin is sequentially glucosylated by the catalysis of UDP-glucose:flavone 4'-O-glucosyltrasferase (F4'GT) and UDP-glucose:flavone 4'-O-glucoside 7-O-glucosyltransferase (F4'G7GT). We identified 150 contigs exhibiting homology with a UDP-glucose-dependent GT in the N. menziesii petal transcriptome and isolated 24 putative full-length GT cDNAs which were then subjected to functional analysis. Two GT cDNAs, NmF4'GT and NmF4'G7GT, which are highly expressed during the early stages of petal development and rarely in leaves, were shown to encode F4'GT and F4'G7GT activities, respectively. Biochemical characterization of the recombinant enzymes revealed that NmF4'GT specifically catalyzed 4'-glucosylation of flavonoids and that NmF4'G7GT specifically catalyzed 7-glucosylation of flavone 4'-O-glucosides and flavones. Apigenin 7,4'-O-diglucoside was efficiently synthesized from apigenin in the presence of recombinant NmF4'GT and NmF4'G7GT. Transgenic tobacco BY-2 cells expressing NmF4'GT and NmF4'G7GT converted apigenin into apigenin 7,4'-O-diglucoside, confirming their activities in vivo. Based on these results, we conclude that these two GTs act co-ordinately to catalyze apigenin 7,4'-O-diglucoside biosynthesis in N. menziesii.

Formation of a Methylenedioxy Bridge in (+)-Epipinoresinol by CYP81Q3 Corroborates with Diastereomeric Specialization in Sesame Lignans.

Plant specialized metabolites are often found as lineage-specific diastereomeric isomers. For example, Sesamum alatum accumulates the specialized metabolite (+)-2-episesalatin, a furofuran-type lignan with a characteristic diastereomeric configuration rarely found in other Sesamum spp. However, little is known regarding how diastereomeric specificity in lignan biosynthesis is implemented in planta. Here, we show that S. alatum CYP81Q3, a P450 orthologous to S. indicum CYP81Q1, specifically catalyzes methylenedioxy bridge (MDB) formation in (+)-epipinoresinol to produce (+)-pluviatilol. Both (+)-epipinoresinol and (+)-pluviatilol are putative intermediates of (+)-2-episesalatin based on their diastereomeric configurations. On the other hand, CYP81Q3 accepts neither (+)- nor (-)-pinoresinol as a substrate. This diastereomeric selectivity of CYP81Q3 is in clear contrast to that of CYP81Q1, which specifically converts (+)-pinoresinol to (+)-sesamin via (+)-piperitol by the sequential formation of two MDBs but does not accept (+)-epipinoresinol as a substrate. Moreover, (+)-pinoresinol does not interfere with the conversion of (+)-epipinoresinol to (+)-pluviatilol by CYP81Q3. Amino acid substitution and CO difference spectral analyses show that polymorphic residues between CYP81Q1 and CYP81Q3 proximal to their putative substrate pockets are crucial for the functional diversity and stability of these two enzymes. Our data provide clues to understanding how the lineage-specific functional differentiation of respective biosynthetic enzymes substantiates the stereoisomeric diversity of lignan structures.

Volatile Glycosylation in Tea Plants: Sequential Glycosylations for the Biosynthesis of Aroma ß-Primeverosides Are Catalyzed by Two Camellia sinensis Glycosyltransferases.

Tea plants (Camellia sinensis) store volatile organic compounds (VOCs; monoterpene, aromatic, and aliphatic alcohols) in the leaves in the form of water-soluble diglycosides, primarily as ß-primeverosides (6-O-ß-D-xylopyranosyl-ß-D-glucopyranosides). These VOCs play a critical role in plant defenses and tea aroma quality, yet little is known about their biosynthesis and physiological roles in planta. Here, we identified two UDP-glycosyltransferases (UGTs) from C. sinensis, UGT85K11 (CsGT1) and UGT94P1 (CsGT2), converting VOCs into ß-primeverosides by sequential glucosylation and xylosylation, respectively. CsGT1 exhibits a broad substrate specificity toward monoterpene, aromatic, and aliphatic alcohols to produce the respective glucosides. On the other hand, CsGT2 specifically catalyzes the xylosylation of the 6'-hydroxy group of the sugar moiety of geranyl ß-D-glucopyranoside, producing geranyl ß-primeveroside. Homology modeling, followed by site-directed mutagenesis of CsGT2, identified a unique isoleucine-141 residue playing a crucial role in sugar donor specificity toward UDP-xylose. The transcripts of both CsGTs were mainly expressed in young leaves, along with ß-primeverosidase encoding a diglycoside-specific glycosidase. In conclusion, our findings reveal the mechanism of aroma ß-primeveroside biosynthesis in C. sinensis. This information can be used to preserve tea aroma better during the manufacturing process and to investigate the mechanism of plant chemical defenses.

The Sg-1 glycosyltransferase locus regulates structural diversity of triterpenoid saponins of soybean.

Triterpene saponins are a diverse group of biologically functional products in plants. Saponins usually are glycosylated, which gives rise to a wide diversity of structures and functions. In the group A saponins of soybean (Glycine max), differences in the terminal sugar species located on the C-22 sugar chain of an aglycone core, soyasapogenol A, were observed to be under genetic control. Further genetic analyses and mapping revealed that the structural diversity of glycosylation was determined by multiple alleles of a single locus, Sg-1, and led to identification of a UDP-sugar-dependent glycosyltransferase gene (Glyma07g38460). Although their sequences are highly similar and both glycosylate the nonacetylated saponin A0-αg, the Sg-1(a) allele encodes the xylosyltransferase UGT73F4, whereas Sg-1(b) encodes the glucosyltransferase UGT73F2. Homology models and site-directed mutagenesis analyses showed that Ser-138 in Sg-1(a) and Gly-138 in Sg-1(b) proteins are crucial residues for their respective sugar donor specificities. Transgenic complementation tests followed by recombinant enzyme assays in vitro demonstrated that sg-1(0) is a loss-of-function allele of Sg-1. Considering that the terminal sugar species in the group A saponins are responsible for the strong bitterness and astringent aftertastes of soybean seeds, our findings herein provide useful tools to improve commercial properties of soybean products.