Researcher basic information

• 博士（農学）, 北海道大学

• https://researchmap.jp/kitaokanaoki?lang=en

• https://jglobal.jst.go.jp/detail?JGLOBAL_ID=201601015832263622
• https://orcid.org/0000-0003-4031-1455

• https://orcid.org/0000-0003-4031-1455

• 201601015832263622

• Plant hormone
• Secondary metabolite
• biosynthesis

• Life Science, Bioorganic chemistry

• Bachelor's degree program, School of Agriculture
• Master's degree program, Graduate School of Agriculture
• Doctoral (PhD) degree program, Graduate School of Agriculture

Research activity information

• Mar. 2024, Japan Society for Bioscience, Biotechnology, and Agrochemistry, JSBBA Award for Young Scientists

• (3R,7S)-11-hydroxy-jasmonic acid is a major oxidative shunt product of jasmonic acid catabolism in Arabidopsis thaliana.
  Kotaro Matsumoto; Maria Mitsui; Takuya Kaji; Naoki Kitaoka; Ruiqi Gao; Taketomo Otaki; Yuho Nishizato; Hideyuki Matsuura; Minoru Ueda
  Nature communications, 21 May 2026, [Peer-reviewed], [International Magazine]
  English, Scientific journal, Jasmonoyl-L-isoleucine (JA-Ile) is a pivotal oxylipin hormone that coordinates growth-defense trade-offs, and its precursor jasmonic acid (JA) is therefore subject to tight metabolic control. For more than a decade, the prevailing dogma has held that jasmonate turnover is dominated by C12-hydroxylation, with JOX dioxygenases acting on JA and CYP94 monooxygenases acting on JA-Ile. Here we revise this dogma by showing that hydroxylation at the C11 position constitutes a major deactivation shunt of JA turnover. Using chemically synthesized (3 R,7S)-11-hydroxy-JA (11-OH-JA) of naturally occurring stereochemistry as a standard, we unambiguously identify 11-OH-JA as the principal shunt product that accumulates in wounded Arabidopsis thaliana. In vitro enzymatic assays, in silico docking, and metabolite analyses in the jox quadruple mutant (joxQ) reveals that JOX1/2/3/4 exclusively converted JA to 11-OH-JA, whereas 12-OH-JA arose from distinct pathway. Moreover, 11-OH-JA failed to bind the COI1-JAZ co-receptor, establishing it as a biologically inactive endpoint of JA catabolism. These findings correct a long-standing misattribution of the JOX product to 12-OH-JA and redefine the metabolic framework of jasmonate. This study provides insights into JA catabolism, highlighting 11-OH-JA as a crucial factor in the attenuation of jasmonate signaling, and thereby redefining the framework of JA turnover in A. thaliana.
• New abietane diterpenes from Origanum vulgare exhibiting lipase inhibitory activity.
  Yu Komata; Ayano Watanabe; Eri Fukushi; Masaru Hashimoto; Jing Wu; Hirokazu Kawagishi; Naoki Kitaoka; Hideyuki Matsuura; Chika Kitaoka-Saito; Kosaku Takahashi
  Bioscience, Biotechnology, and Biochemistry, 27 Mar. 2026, [Peer-reviewed], [International Magazine]
  English, Scientific journal, Many herbs and spices have been reported to exhibit various biological activities, including antioxidant effects, antimicrobial activity, and antitumor activity; consequently, they are expected to contain novel bioactive compounds. In this study, anti-obesity agents were identified in several herbs and spices by screening for inhibitors of lipase, a key enzyme involved in lipid digestion. The extract of Origanum vulgare (oregano) demonstrated considerable lipase inhibitory activity. The active constituents from this plant were isolated by subjecting the oregano extract to several separation protocols, including SiO2 gel column chromatography and reversed-phase high-performance liquid chromatography. The purification process was guided by lipase inhibitory activity, affording origanone A (1) and origanone B (2) as novel abietane diterpenes. Notably, these compounds exhibited moderate lipase inhibitory activity. These findings indicate the potential of oregano and its active constituents as functional food ingredients for regulating lipid levels and obesity.
• Synthesis of 12-hydroxyjasmonoyl-L-isoleucine and its isomers and their biological activity against rice.
  Tomohisa Minamino; Yoshitaka Yokota; Naoki Kitaoka; Hideyuki Matsuura
  Bioscience, Biotechnology, and Biochemistry, 19 Jan. 2026, [Corresponding author], [International Magazine]
  English, Scientific journal, Jasmonate is a plant hormone that regulates development and defense responses. Jasmonoyl-L-isoleucine (JA-Ile) is a ligand for the most studied jasmonate co-receptor, COI1-JAZ, in seed plants. 12-Oxygenation to 12-hydroxyjasmonoyl-L-isoleucine (12-OH-JA-Ile) is a major metabolic pathway of JA-Ile. Moreover, 12-OH-JA-Ile is a selective ligand for some COI1-JAZ pairs in Arabidopsis thaliana. However, few studies have reported on the activity of 12-OH-JA-Ile in rice (Oryza sativa L.). In this study, we synthesized 12-OH-JA-Ile and its isomers, and evaluated their biological activities against rice. 12-OH-JA-Ile inhibited root elongation but did not induce the biosynthesis of momilactone A, a phytoalexin. These results suggested that 12-OH-JA-Ile selectively induced a jasmonate response in rice. The bioactivity of the E-isomer of 12-OH-JA-Ile revealed that the Z-olefin was necessary for root inhibitory activity.
• Irrigation with ABA Solution Induces the Accumulation of Pyrethrin II in Seedlings of Pyrethrum (Tanacetum cinerariifolium)
  Kisumi Takiguchi; Shiro Inoue; Kazuhiko Matsuda; Naoki Kitaoka; Hideyuki Matsuura
  Journal of Plant Growth Regulation, Springer Science and Business Media LLC, 05 Jan. 2026, [Peer-reviewed]
  Scientific journal
• Investigating Biologically Active Compounds from the Filamentous Fungi Bjerkandera adusta and Irpex lacteus That Inhibit the Growth of Marchantia polymorpha
  Vera Fitriya Ersalena; Akari Tada; Shiro Inoue; Naoki Kitaoka; Hideyuki Matsuura
  Natural Product Communications, 20, 10, SAGE Publications, 09 Oct. 2025, [Peer-reviewed]
  Scientific journal, Background
  
  Marchantia polymorpha is a model organism for research on evolutionary molecular-microbe interactions. Filamentous fungi pathogenic to M. polymorpha have been reported and a necrotrophic-like infection process has been proposed according to experiments conducted in the laboratory, but many aspects of M. polymorpha and microbes interaction remain unknown.
  
  Objective
  
  Field observations have been done and indicated that several kinds of fungi had ability to infect M. polymorpha and among of them, Bjerkandera adusta and Irpex lacteus infect M. polymorpha , and laboratory experiments have revealed that these fungi have a strong ability to infect M. polymorpha . Therefore, it was hypothesized that these fungi may produce specialized metabolites that lead to effectively invade into the liverwort. The aim of this research was to determine the chemical structures of the specialized metabolites and evaluate the biological activities of the compounds.
  
  Materials and Methods
  
  B. adusta and I. lacteus were obtained from GenBank Project, NARO. Male accessions of M. polymorpha, Takaragaike-1, were used for bioassay. The fungi were grown in potato dextrose broth medium. The culture filtrates were filtered and concentrated, and EtOAc (3 L) and H ₂ O (1 L) were added to the crude material. Crude extracts obtained from the EtOAc were subjected to several kinds of purification steps to afford methyl vanillin from B. adusta and tremutin E from I. lacteus .
  
  Results
  
  Methyl vanillin and tremutin E were isolated from B. adusta and I. lacteus , respectively, according to a guidance of growth inhibitory activity-guided fractionations and identified using mass spectroscopic data together with 1D and 2D NMR techniques.
  
  Conclusion
  
  Methyl vanillin and tremutin E inhibited the growth of M. polymorpha with almost 100-fold stronger activity than that of acetic acid, a pivotal active ingredient of commercial anti-liverwort agent.
• AtGH3.10 and JAR1 Produce 12-Hydroxyjasmonoyl-L-isoleucine from 12-Hydroxyjasmonic Acid in Arabidopsis thaliana.
  Katsunari Oki; Akane Enoki; Yoshitaka Yokota; Taiki Kurihara; Takafumi Shimizu; Wataru Saburi; Takayuki Tohge; Haruhide Mori; Guido Van den Ackerveken; Naoki Kitaoka; Hideyuki Matsuura
  ChemBioChem, 26, e202500151, 11 Sep. 2025, [Peer-reviewed], [Corresponding author], [International Magazine]
  English, Scientific journal, Jasmonates are plant hormones that regulate plant defense and development. 7-iso-Jasmonoyl-l-isoleucine (JA-Ile) is a representative active jasmonate which is biosynthesized from 7-iso-jasmonic acid (JA) by the jasmonoyl-amido synthases JASMONATE RESISTANT 1 (JAR1) and AtGH3.10 in Arabidopsis thaliana. 12-Hydroxy-7-iso-jasmonoyl-l-isoleucine (12-OH-JA-Ile) is another active jasmonate, and 12-hydroxylation of JA-Ile is considered the major biosynthetic pathway toward 12-OH-JA-Ile. Previous report elucidated that recombinant JAR1 showed a weak activity against 12-hydroxy-7-iso-jasmonic acid (12-OH-JA). However, the direct conversion from 12-OH-JA to 12-OH-JA-Ile in planta and the enzyme activity of AtG3.10 against 12-OH-JA have never been reported. Herein, a feeding experiment with deuterated 12-OH-JA confirms the direct conversion of 12-OH-JA to 12-OH-JA-Ile in wild-type Arabidopsis plants. The conversion from 12-OH-JA to 12-OH-JA-Ile is not observed in jar1 gh3.10 double mutant, suggesting that 12-OH-JA is converted to 12-OH-JA-Ile by JAR1 and AtGH3.10. Notably, enzyme assays show that the catalytic efficiency with 12-OH-JA for AtGH3.10 is higher than those with JA for AtGH3.10 and with 12-OH-JA for JAR1. Comparative analysis of JAR1 and AtGH3.10 structures and site-directed mutation analysis reveals that Ser120 in AtGH3.10 is the key amino acid residue responsible for its high catalytic efficiency against 12-OH-JA.
• Existence, biosynthesis, metabolism, bioactivities, and biological functions of 12-hydroxyjasmonates.
  Naoki Kitaoka
  Bioscience, Biotechnology, and Biochemistry, 30 Aug. 2025, [Peer-reviewed], [Lead author, Corresponding author], [International Magazine]
  English, Scientific journal, Jasmonates, including (+)-7-iso-jasmonic acid (JA) and related compounds, are plant hormones that regulate both developmental and defense responses. Among jasmonates, 12-hydroxyjasmonates, such as 12-hydroxyjasmonic acid (12-OH-JA) and 12-hydroxyjasmonoyl-L-isoleucine (12-OH-JA-Ile), are commonly observed in various plant species. 12-Hydroxyjasmonates regulate jasmonate responses, both dependent and independent of CORONATINE-INSENSIVE 1 (COI1) and JASMONATE ZIM-DOMAIN (JAZ) proteins, which are the most studied jasmonate co-receptors. This review summarizes the existence, biosynthesis, metabolism, bioactivities, and biological functions of 12-hydroxyjasmonates.
• Unveiling the presence of jasmonoyl-L-isoleucine in 3 species of moss belonging to Bryophytes.
  Vera Fitriya Ersalena; Naoki Kitaoka; Hideyuki Matsuura
  Bioscience, Biotechnology, and Biochemistry, 89, 8, 1177, 1181, 23 Jul. 2025, [Peer-reviewed], [International Magazine]
  English, Scientific journal, There is no existing evidence of the existence of jasmonates and (+)-7-iso-Jasmonoyl-ʟ-isoleucine (JA-l-Ile) in Bryophytes. Mosses belong to Bryophytes, and it was found that 3 kinds of mosses, Calohypnum plumiforme, Lencobryum bowringii, and Pyrrhobryum dozyanum, accumulated detectable levels of endogenous JA-l-Ile in the aerial parts, but not in Bartramia pomiformis belonging to the same plant group.
• Isolation and Identification of the Antibacterial Compounds Produced by Maillard Reaction of Xylose with Phenylalanine or Proline.
  Kazuho Aonishi; Shungo Miyao; Lisa Yokoi; Naoki Kitaoka; Kento Koyama; Hideyuki Matsuura; Shigenobu Koseki
  Journal of Agricultural and Food Chemistry, 72, 28, 16010, 16017, Jul. 2024, [Peer-reviewed], [International Magazine]
  English, Scientific journal, Maillard reaction products (MRPs) of xylose with phenylalanine and xylose with proline exhibit high antibacterial activity. However, the active antibacterial compounds in MRPs have not yet been identified or isolated. This study aimed to isolate the active compounds in the two antibacterial MRPs. The organic layer of the MRP solution was separated and purified using silica gel chromatography and high-performance liquid chromatography. The chemical structures of the isolated compounds were determined by mass spectrometry and nuclear magnetic resonance spectroscopy. The compounds inhibited the growth of Bacillus cereus and Salmonella Typhimurium at 25 °C for 7 days at a concentration of 0.25 mM. Furthermore, the isolated compounds inhibited the growth of naturally occurring microflora of lettuce and chicken thighs at 25 °C for 2 days at a concentration of 0.5-1.0 mM. The antibacterial compounds found in MRPs demonstrated a wide range of effectiveness and indicated their potential as alternative preservatives.
• Isolation and Structure Determination of cis-OPDA-α-Monoglyceride from Arabidopsis thaliana.
  Shotaro Hirota; Yusuke Ito; Shiro Inoue; Naoki Kitaoka; Tohru Taniguchi; Kenji Monde; Kosaku Takahashi; Hideyuki Matsuura
  Journal of Natural Products, 87, 1358, 1367, Apr. 2024, [Peer-reviewed], [International Magazine]
  English, Scientific journal, cis-12-oxo-Phytodieneoic acid-α-monoglyceride (1) was isolated from Arabidopsis thaliana. The chemical structure of 1 was elucidated based on exhaustive 1D and 2D NMR spectroscopic measurements and supported by FDMS and HRFDMS data. The absolute configuration of the cis-OPDA moiety in 1 was determined by comparison of 1H NMR spectra and ECD measurements. With respect to the absolute configuration of the β-position of the glycerol backbone, the 2:3 ratio of (S) to (R) was determined by making ester-bonded derivatives with (R)-(+)-α-methoxy-α-trifluoromethylphenylacetyl chloride and comparing 1H NMR spectra. Wounding stress did not increase endogenous levels of 1, and it was revealed 1 had an inhibitory effect of A. thaliana post germination growth. Notably, the endogenous amount of 1 was higher than the amounts of (+)-7-iso-jasmonic acid and (+)-cis-OPDA in intact plants. 1 also showed antimicrobial activity against Gram-positive bacteria, but jasmonic acid did not. It was also found that α-linolenic acid-α-monoglyceride was converted into 1 in the A. thaliana plant, which implied α-linolenic acid-α-monoglyceride was a biosynthetic intermediate of 1.
• Isolation, structural elucidation, and biological activity of a novel isocoumarin from the dark septate endophytic fungus Phialocephala fortinii
  Kei Bando; Ryoga Kushibe; Naoki Kitaoka; Yutaka Tamai; Kazuhiko Narisawa; Hideyuki Matsuura
  Zeitschrift für Naturforschung C, 79, 89, 92, Mar. 2024, [Peer-reviewed], [Corresponding author]
  Scientific journal
• Investigation of the Biosynthesis Pathway that Generates cis-Jasmone.
  Shiro Inoue; Hiromu Tsuzuki; Kazuhiko Matsuda; Naoki Kitaoka; Hideyuki Matsuura
  ChemBioChem, 25, e202300593, Nov. 2023, [Peer-reviewed], [International Magazine]
  English, Scientific journal, Researchers have established that (+)-7-iso-jasmonic acid ((+)-7-iso-JA) is an intermediate in the production of cis-jasmone (CJ); however, the biosynthetic pathway of CJ has not been fully described. Previous reports stated that CJ, a substructure of pyrethrin II produced by pyrethrum (Tanacetum cinerariifolium), is not biosynthesized through this biosynthetic pathway. To clarify the ambiguity, stable isotope-labelled jasmonates were synthesized, and compounds were applied to apple mint (Mentha suaveolens) via air propagation. The results showed that cis-jasmone is not generated from intermediate (+)-7-iso-JA, and (+)-7-iso-JA is not produced from 3,7-dideydro-JA (3,7-ddh-JA); however, 3,7-didehydro-JA and 4,5-didehydro-7-iso-JA were converted into CJ and JA, respectively.
• Airborne Methyl Jasmonate is Metabolized to Jasmonic Acid and 12-Hydroxyjasmonic Acid, and Induces Jasmonate Biosynthesis in Marchantia polymorpha
  Hiromu Tsuzuki; Naoki Kitaoka; Shiro Inoue; Kosaku Takahashi; Hideyuki Matsuura
  ChemistrySelect, 8, 21, Jun. 2023, [Peer-reviewed], [Corresponding author]
  English, Scientific journal
• Biological Activity of Anti-bolting Compound, alpha-(7Z,10Z,13Z)-hexadeca-7,10,13-trienoic Acid Monoglyceride to Reduce the Endogenous Amount of Gibberellins
  Tsuyoshi Ogihara; Shunpei Shikama; Akihisa Ishii; Syotaro Hirota; Junichi Kashiwagi; Kaien Fujino; Yuki Mitsui; Takafumi Shimizu; Mitsunori Seo; Naoki Kitaoka; Yasunori Koda; Hideyuki Matsuura
  Journal of Plant Growth Regulation, 43, 3075, 3087, Apr. 2023, [Peer-reviewed]
  English, Scientific journal
• Pennelliiside D, a New Acyl Glucose from Solanum pennellii and Chemical Synthesis of Pennelliisides.
  Rishni Masimbula; Hiroto Kobayashi; Tenki Nakashima; Yurika Nambu; Naoki Kitaoka; Hideyuki Matsuura
  Molecules (Basel, Switzerland), 27, 12, 3728, 09 Jun. 2022, [Peer-reviewed], [International Magazine]
  English, Scientific journal, Acyl glucoses are a group of specialized metabolites produced by Solanaceae. Solanum pennellii, a wild-type tomato plant, produces acyl glucoses in its hair-like epidermal structures known as trichomes. These compounds have been found to be herbicides, microbial growth inhibitors, or allelopathic compounds. However, there are a few reports regarding isolation and investigation of biological activities of acyl glucoses in its pure form due to the difficulty of isolation. Here, we report a new acyl glucose, pennelliiside D, isolated and identified from S. pennellii. Its structure was determined by 1D NMR and 2D NMR, together with FD-MS analysis. To clarify the absolute configuration of the acyl moiety of 2-methylbutyryl in the natural compound, two possible isomers were synthesized starting from β-D-glucose pentaacetate. By comparing the spectroscopic data of natural and synthesized compounds of isomers, the structure of pennelliiside D was confirmed to be 3,4-O-diisobutyryl-2-O-((S)-2-methylbutyryl)-D-glucose. Pennelliiside D and its constituent fatty acid moiety, (S)-2-methylbutanoic acid, did not show root growth-inhibitory activity. Additionally, in this study, chemical synthesis pathways toward pennelliisides A and B were adapted to give 1,6-O-dibenzylpennelliisides A and B.
• A carlactonoic acid methyltransferase that contributes to the inhibition of shoot branching in Arabidopsis
  Kiyoshi Mashiguchi; Yoshiya Seto; Yuta Onozuka; Sarina Suzuki; Kiyoko Takemoto; Yanting Wang; Lemeng Dong; Kei Asami; Ryota Noda; Takaya Kisugi; Naoki Kitaoka; Kohki Akiyama; Harro Bouwmeester; Shinjiro Yamaguchi
  Proceedings of the National Academy of Sciences, 119, 14, e2111565119, Proceedings of the National Academy of Sciences, 05 Apr. 2022, [Peer-reviewed], [International Magazine]
  English, Scientific journal, Significance
  
  Strigolactones (SLs) are a group of apocarotenoid hormones, which regulates shoot branching and other diverse developmental processes in plants. The major bioactive form(s) of SLs as endogenous hormones has not yet been clarified. Here, we identify an
  Arabidopsis
  methyltransferase, CLAMT, responsible for the conversion of an inactive precursor to a biologically active SL that can interact with the SL receptor in vitro. Reverse genetic analysis showed that this enzyme plays an essential role in inhibiting shoot branching. This mutant also contributed to specifying the SL-related metabolites that could move from root to shoot in grafting experiments. Our work has identified a key enzyme necessary for the production of the bioactive form(s) of SLs.
  
• AtGH3 .10 is another jasmonic acid‐amido synthetase in Arabidopsis thaliana
  Jay C. Delfin; Yuri Kanno; Mitsunori Seo; Naoki Kitaoka; Hideyuki Matsuura; Takayuki Tohge; Takafumi Shimizu
  The Plant Journal, 110, 1082, 1096, Wiley, 22 Mar. 2022, [Peer-reviewed]
  Scientific journal
• Potato tuber-inducing activities of jasmonic acid and related-compounds (II).
  Kanji Miyawaki; Shiro Inoue; Naoki Kitaoka; Hideyuki Matsuura
  Bioscience, Biotechnology, and Biochemistry, 85, 12, 2378, 2382, 24 Nov. 2021, [International Magazine]
  English, Scientific journal, New information is being accumulated for plant-derived oxylipins, such as jasmonic acid (JA) amino acid conjugates. However, these compounds have not being examined for their activity in promoting potato tuber formation. It was found that (-)-JA had the highest activity followed cis-(-)-OPDA, (+)-4, 5-didehydroJA, cis-(+)-OPDA-l-Ile, and (-)-JA-l-Ile, -Leu, -Phe, -Val, although iso-OPDA and 3,7-didehydroJA did not exhibit activity.
• Verification of the versatility of the in vitro enzymatic reaction giving (+)-cis-12-Oxo-phytodienoic acid.
  Yusuke Ito; Kento Sasaki; Tsuyoshi Ogihara; Naoki Kitaoka; Kosaku Takahahi; Hideyuki Matsuura
  Bioorganic & Medicinal Chemistry Letters, 49, 128284, 128284, 01 Oct. 2021, [Peer-reviewed], [International Magazine]
  English, Scientific journal, Jasmonic acid (JA) is a plant hormone involved in the defense response against insects and fungi. JA is synthesized from α-linolenic acid (LA) by the octadecanoid pathway in plants. 12-oxo-Phytodienoic acid (OPDA) is one of the biosynthetic intermediates in this pathway. The reported stereo selective total synthesis of cis-(+)-OPDA is not very efficient due to the many steps involved in the reaction as well as the use of water sensitive reactions. Therefore, we developed an enzymatic method for the synthesis of OPDA using acetone powder of flax seed and allene oxide cyclase (PpAOC2) from Physcomitrella patens. From this method, natural cis-(+)-OPDA can be synthesized in the high yield of approximately 40%. In this study, we investigated the substrate specificity of the enzymatic synthesis of other OPDA analogs with successions to afford OPDA amino acid conjugates, dinor-OPDA (dn-OPDA), and OPDA monoglyceride, and it was suggested that the biosynthetic pathway of arabidopsides could occur via MGDG.
• A promiscuous fatty acid ω‐hydroxylase CYP94A90 is likely to be involved in biosynthesis of a floral nitro compound in loquat ( Eriobotrya japonica )
  Takuya Yamaguchi; Yumi Matsui; Naoki Kitaoka; Yasumasa Kuwahara; Yasuhisa Asano; Hideyuki Matsuura; Yukari Sunohara; Hiroshi Matsumoto
  New Phytologist, 231, 3, 1157, 1170, Wiley, 31 Aug. 2021, [Peer-reviewed]
  Scientific journal
• Bioproduction of 4-Vinylphenol and 4-Vinylguaiacol β-Primeverosides Using Transformed Bamboo Cells Expressing Bacterial Phenolic Acid Decarboxylase
  Naoki Kitaoka; Taiji Nomura; Shinjiro Ogita; Yasuo Kato
  Applied Biochemistry and Biotechnology, 193, 7, 2061, 2075, 05 Feb. 2021, [Peer-reviewed], [Lead author, Corresponding author], [International Magazine]
  English, Scientific journal, Phenolic acid decarboxylase (PAD) catalyzes the decarboxylation of hydroxycinnamic acids to produce hydroxystyrenes, which serve as starting materials for the production of polymers. Bamboo (Phyllostachys nigra; Pn) cells, a suitable host for producing phenylpropanoid-derived compounds, were transformed to express PAD of Bacillus amyloliquefaciens (BaPAD). BaPAD-transformed cells accumulated several metabolites that were not detected in wild-type Pn cells or BaPAD-negative transformant. Two major metabolites were isolated from BaPAD-transformed cells, and elucidation of their chemical structures confirmed these as 4-vinylphenol β-primeveroside (4-VPP) and 4-vinylguaiacol β-primeveroside (4-VGP). The production titers of 4-VPP and 4-VGP reached 48 and 33 mg/L at the maximum, respectively. Feeding experiments with 4-vinylphenol (4-VP), 4-vinylguaiacol (4-VG), and their glucosides indicated that 4-VPP and 4-VGP are formed by sequential glycosylation of 4-VP and 4-VG via their corresponding glucosides. Our results demonstrate the versatility of Pn cells for producing styrene derivatives, and indicate the presence of a unique glycosylation pathway to produce 4-VPP and 4-VGP in Pn cells.
• Interdependent evolution of biosynthetic gene clusters for momilactone production in rice
  Naoki Kitaoka; Juan Zhang; Richard K Oyagbenro; Benjamin Brown; Yisheng Wu; Bing Yang; Zhaohu Li; Reuben J Peters
  The Plant Cell, 33, 2, 290, 305, Oxford University Press ({OUP}), Feb. 2021, [Peer-reviewed], [Lead author]
  Scientific journal
• Bioproduction of glucose conjugates of 4-hydroxybenzoic and vanillic acids using bamboo cells transformed to express bacterial 4-hydroxycinnamoyl-CoA hydratase/lyase.
  Naoki Kitaoka; Taiji Nomura; Shinjiro Ogita; Yasuo Kato
  Journal of Bioscience and Bioengineering, 130, 1, 89, 97, Elsevier BV, Jul. 2020, [Peer-reviewed], [Lead author, Corresponding author], [Domestic magazines]
  English, Scientific journal, Rational metabolic-flow switching, which we proposed recently, is an effective strategy to produce an exogenous high-value natural product using transformed plant cells; the proof of this concept was demonstrated using bamboo (Phyllostachys nigra; Pn) cells as a model system. Pn cells were transformed to express 4-hydroxycinnamoyl-CoA hydratase/lyase of Pseudomonas putida KT2440 (PpHCHL), which catalyzes the formation of 4-hydroxybenzaldehyde and vanillin from p-coumaroyl-CoA and feruloyl-CoA, respectively. The PpHCHL-transformed cells accumulated glucose conjugates of 4-hydroxybenzoic acid and vanillic acid, indicating that the PpHCHL products (aldehydes) were further metabolized by inherent enzymes in the Pn cells. The production titers of 4-hydroxybenzoic acid glucose ester, vanillic acid glucose ester, and 4-hydroxybenzoic acid glucoside reached 1.7, 0.17, and 0.14 g/L at the maximum, respectively. These results proved the versatility of Pn cells for producing vanillin-related compounds based on rational metabolic-flow switching.
• Cobalt-dependent inhibition of nitrite oxidation in Nitrobacter winogradskyi.
  Richard Metzner; Taiji Nomura; Naoki Kitaoka; Akinori Ando; Jun Ogawa; Yasuo Kato
  Journal of Bioscience and Bioengineering, 128, 4, 463, 467, Oct. 2019, [Peer-reviewed], [Domestic magazines]
  English, Scientific journal, Nitrobacter winogradskyi is an abundant, intensively studied autotrophic nitrite-oxidizing bacterium, which is frequently used as a model strain in the two-step nitrification of ammonia (NH3) to nitrate (NO3-) via nitrite (NO2-), either in activated sludge, agricultural field studies or more recently in artificial microbial consortia for organic hydroponics. We observed a hitherto unknown cobalt ion-dependent inhibition of cell growth and NO2- oxidation activity of N. winogradskyi in a mineral medium, which strongly depended on accompanying Ca2+ and Mg2+ concentrations. This inhibition was bacteriostatic, but susceptible to natural chelators. l-Histidine effectively restored cell growth and NO2- oxidation activity of N. winogradskyi in mineral media containing Co2+ with >90% recovery. Our results suggest that Co2+ competed with alkaline earth metals during uptake and that its toxicity was significantly reduced by complexation.
• Molecular diversity of tuliposide B-converting enzyme in tulip (Tulipa gesneriana): identification of the third isozyme with a distinct expression profile.
  Taiji Nomura; Ryo Kuchida; Naoki Kitaoka; Yasuo Kato
  Bioscience, Biotechnology, and Biochemistry, 82, 5, 1, 11, 23 Feb. 2018, [Peer-reviewed], [International Magazine]
  English, Scientific journal, 6-Tuliposide B (PosB), a major secondary metabolite that accumulates in tulip (Tulipa gesneriana), is converted to the antibacterial lactone, tulipalin B (PaB), by PosB-converting enzyme (TCEB). TgTCEB1 and TgTCEB-R, which encode TCEB, are specifically expressed in tulip pollen and roots, respectively, but are hardly expressed in other tissues (e.g. leaves) despite the presence of substantial PosB-converting activity, suggesting the existence of another TCEB isozyme. Here, we describe the identification of TgTCEB-L ("L" for leaf), a paralog of TgTCEB1 and TgTCEB-R, from leaves via native enzyme purification. The enzymatic characters of TgTCEB-L, including catalytic activity and subcellular localization, were substantially the same as those of TgTCEB1 and TgTCEB-R. However, TgTCEB-L did not exhibit tissue-specific expression. Identification of TgTCEB-L explains the PosB-converting activity detected in tissues where TgTCEB1 and TgTCEB-R transcripts could not be detected, indicating that tulip subtilizes the three TgTCEB isozymes depending on the tissue.
• Investigating inducible short-chain alcohol dehydrogenases/reductases clarifies rice oryzalexin biosynthesis
  Naoki Kitaoka; Yisheng Wu; Jiachen Zi; Reuben J. Peters
  The Plant Journal, 88, 2, 271, 279, Oct. 2016, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Hormone crosstalk in wound stress response: wound-inducible amidohydrolases can simultaneously regulate jasmonate and auxin homeostasis in Arabidopsis thaliana
  Tong Zhang; Arati N. Poudel; Jeremy B. Jewell; Naoki Kitaoka; Paul Staswick; Hideyuki Matsuura; Abraham J. Koo
  Journal of Experimental Botany, 67, 7, 2107, 2120, Mar. 2016, [Peer-reviewed]
  English, Scientific journal
• Optimization of recombinant expression enables discovery of novel cytochrome P450 activity in rice diterpenoid biosynthesis
  Naoki Kitaoka; Yisheng Wu; Meimei Xu; Reuben J. Peters
  Applied Microbiology and Biotechnology, 99, 18, 7549, 7558, Sep. 2015, [Peer-reviewed], [Lead author]
  English, Scientific journal
• The Application of Synthetic Biology to Elucidation of Plant Mono-, Sesqui-, and Diterpenoid Metabolism
  Naoki Kitaoka; Xuan Lu; Bing Yang; Reuben J. Peters
  Molecular Plant, 8, 1, 6, 16, Jan. 2015, [Peer-reviewed], [Lead author]
  English
• Endoplasmic Reticulum-associated Inactivation of the Hormone Jasmonoyl-L-Isoleucine by Multiple Members of the Cytochrome P450 94 Family in Arabidopsis
  Abraham J. Koo; Caitlin Thireault; Starla Zemelis; Arati N. Poudel; Tong Zhang; Naoki Kitaoka; Federica Brandizzi; Hideyuki Matsuura; Gregg A. Howe
  Journal of Biological Chemistry, 289, 43, 29728, 29738, Oct. 2014, [Peer-reviewed]
  English, Scientific journal
• CYP94B3 activity against jasmonic acid amino acid conjugates and the elucidation of 12-O-beta-glucopyranosyl-jasmonoyl-L-isoleucine as an additional metabolite
  Naoki Kitaoka; Hiroshi Kawaide; Naruki Amano; Takuya Matsubara; Kensuke Nabeta; Kosaku Takahashi; Hideyuki Matsuura
  Phytochemistry, 99, 6, 13, Mar. 2014, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Transportation of de novo synthesized jasmonoyl isoleucine in tomato
  Hideyuki Matsuura; Syohei Takeishi; Naoki Kiatoka; Chizuru Sato; Kae Sueda; Chikara Masuta; Kensuke Nabeta
  Phytochemistry, 83, 25, 33, Nov. 2012, [Peer-reviewed]
  English, Scientific journal
• Biological Activity and Tissue Specific Accumulation of Fluorescently Labeled Methyl Jasmonate
  Naoki Kitaoka; Yuzou Sano; Seizo Fujikawa; Kensuke Nabeta; Hideyuki Matsuura
  Natural Product Communications, 7, 2, 215, 218, Feb. 2012, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Arabidopsis CYP94B3 Encodes Jasmonyl-L-Isoleucine 12-Hydroxylase, a Key Enzyme in the Oxidative Catabolism of Jasmonate
  Naoki Kitaoka; Takuya Matsubara; Michio Sato; Kosaku Takahashi; Shinji Wakuta; Hiroshi Kawaide; Hirokazu Matsui; Kensuke Nabeta; Hideyuki Matsuura
  Plant and Cell Physiology, 52, 10, 1757, 1765, Oct. 2011, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Potato Tuber Cell Expansion-Inducing Activity of Stereochemically Restricted JA Analogs
  Naoki Kitaoka; Eri Fukushi; Yasunori Koda; Kensuke Nabeta; Hideyuki Matsuura
  Bioscience, Biotechnology, and Biochemistry, 73, 8, 1872, 1876, Aug. 2009, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Isolation and Structural Elucidation of a New Cyclohexenone Compound from Lasiodiplodia theobromae
  Naoki Kitaoka; Kensuke Nabeta; Hideyuki Matsuura
  Bioscience, Biotechnology, and Biochemistry, 73, 8, 1890, 1892, Aug. 2009, [Peer-reviewed], [Lead author]
  English, Scientific journal

• ゼニゴケにおけるジャスモン酸の生合成
  北岡 直樹; 都築 玄武; 高橋 公咲; 松浦 英幸, アグリバイオ, 7, 3, 60, 63, Mar. 2023
• Evolution of biosynthesis and signaling pathway of jasmonates
  Naoki Kitaoka; Kosaku Takahashi, 植物の生長調節, 56, 2, 77, 84, Dec. 2021
  Japanese
• オリザレキシン生合成における酸化酵素の働き:化学構造の多様性はどのようにもたらされるか？
  北岡 直樹, 化学と生物, 55, 9, 585, 586, 2017
  公益社団法人 日本農芸化学会, Japanese
• 植物ホルモン・ジャスモン酸の主要な不活性化経路 : ジャスモン酸イソロイシン12位水酸化酵素CYP94B3の発見
  北岡 直樹; 松浦 英幸, 化学と生物, 50, 3, 156, 157, 01 Mar. 2012
  公益社団法人 日本農芸化学会, Japanese

• ジャスモン酸の活性調節機構の解明を目指して
  北岡 直樹
  北海道植物学会2025年度大会, 09 Dec. 2025, Invited oral presentation
  09 Dec. 2025, [Invited]
• ジャスモン酸の活性調節機構の解明
  北岡 直樹
  第11回 植物二次代謝フロンティア研究会, 22 Oct. 2025, Invited oral presentation
  21 Oct. 2025 - 22 Oct. 2025, [Invited]
• 植物ホルモン・ジャスモン酸の活性調節機構
  北岡 直樹
  第１７回化学生態学研究会, 14 Jun. 2025, Invited oral presentation
  13 Jun. 2025 - 14 Jun. 2025, [Invited]
• 植物の防御応答に関わる天然有機化合物の生合成機構と生理作用
  北岡 直樹
  2024年度 日本農芸化学会北海道支部 第２回学術講演会, 30 Nov. 2024, Invited oral presentation
  30 Nov. 2024 - 01 Dec. 2024, [Invited]
• 植物の防御応答関連物質の生成機構の解明
  北岡 直樹
  有機合成化学協会北海道支部 若手研究者のための有機化学札幌セミナー, Nov. 2021
  [Invited]

• 天然物化学特論, 2024年, 修士課程, 農学院
• 生物学実験Ⅰ, 2024年, 学士課程, 農学部
• 化学実験Ⅰ, 2024年, 学士課程, 農学部
• 有機化学Ⅰ, 2024年, 学士課程, 農学部
• 生物有機化学, 2024年, 学士課程, 農学部
• 一般教育演習(ﾌﾚｯｼｭﾏﾝｾﾐﾅｰ), 2024年, 学士課程, 全学教育

• The Japanese Society for Chemical Regulation of Plants
• The Japanese Society of Plant Physiologists
• Japan Society for Bioscience, Biotechnology, and Agrochemistry

• 抗菌活性を有する新規メラノイジンの製造方法とその応用
  Patent right, 小関成樹; 北岡直樹; 松浦英幸, 国立大学法人北海道大学
  特願2021-170957