title: Functional characterization of ZmTPS7 reveals a maize τ-cadinol synthase involved in stress response.
abstract: Maize ( Zea mays ) terpene synthase 7 (ZmTPS7) was characterized as a τ-cadinol synthase, which exhibited constitutive and inducible gene expression patterns, suggesting involvement in stress response. Maize produces a variety of terpenoids involved in defense response. Despite some terpene synthases (TPSs) responsible for these terpenoids have been characterized, biosynthesis of many terpenes, particularly sesquiterpenes, which were produced in response to biotic or abiotic stress, remains largely unknown. Here, we characterized ZmTPS7 biochemically through recombinant expression in Escherichia coli and detected that it catalyzed formation of a blend of sesquiterpenes and sesquiterpenoid alcohols as the sesquiterpene synthase through GC-MS analysis. Subsequently, the major product was purified and identified as τ-cadinol through nuclear magnetic resonance spectroscopy (NMR) analysis, which was also detected in maize tissues infected by pathogen fungus for the first time. ZmTPS7 constitutively expressed in aerial tissues while with trace amount of transcript in roots. Fungus spore inoculation and methyl jasmonate (MeJA) treatment induced gene expression of ZmTPS7 in leaves, while exogenous ABA induced ZmTPS7 dramatically in roots, suggesting that ZmTPS7 might be involved in stress response. τ-cadinol was quantified in infected maize tissues with the concentration of ~200 ng/g fresh weight, however, which was much lower than the inhibitory one on two tested necrotrophic fungi. Such evidences indicate that anti-fungal activity of τ-cadinol is not physiologically relevant, and further investigation is needed to clarify its biological functions in maize. Taken together, ZmTPS7 was characterized as the τ-cadinol synthase and suggested to be involved in stress response, which also increased the diversity of maize terpenoid profile.
authors.affiliation: Institute of Ecological Agriculture, Sichuan Agricultural University, Chengdu, 611130, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Ren
authors.affiliation: Institute of Ecological Agriculture, Sichuan Agricultural University, Chengdu, 611130, China.
authors.forename: Hongjie
authors.initials: H
authors.lastname: Mao
authors.affiliation: Institute of Ecological Agriculture, Sichuan Agricultural University, Chengdu, 611130, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Liang
authors.affiliation: Institute of Ecological Agriculture, Sichuan Agricultural University, Chengdu, 611130, China.
authors.forename: Jiang
authors.initials: J
authors.lastname: Liu
authors.affiliation: Institute of Ecological Agriculture, Sichuan Agricultural University, Chengdu, 611130, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Shu
authors.affiliation: Institute of Ecological Agriculture, Sichuan Agricultural University, Chengdu, 611130, China. qwang@sicau.edu.cn.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000235:genetics / Q000378:metabolism*; D000935:Antifungal Agents / Q000494:pharmacology; D066241:Carbon-13 Magnetic Resonance Spectroscopy; D005658:Fungi / Q000187:drug effects; D008401:Gas Chromatography-Mass Spectrometry; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D007477:Ions; D008670:Metals / Q000494:pharmacology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D066244:Proton Magnetic Resonance Spectroscopy; D060888:Real-Time Polymerase Chain Reaction; D013729:Terpenes / Q000378:metabolism*; D003313:Zea mays / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000502:physiology*
chemical_list: D000935:Antifungal Agents; D007477:Ions; D008670:Metals; D010940:Plant Proteins; D013729:Terpenes; C445364:cadinol; D019883:Alkyl and Aryl Transferases; C108877:terpene synthase
keywords: ABA; Sesquiterpene; Terpene synthase; Terpenoid; Zea mays