Transcriptomics-Driven Discovery of New Meroterpenoid Rhynchospenes Involved in the Virulence of the Barley Pathogen Rhynchosporium commune

Reynnaldi Darma, Zhuo Shang, joe Bracegirdle, Stephen Moggach, Megan McDonald, Andrew M. Piggott, Peter Solomon, Yit-Heng Chooi

    Research output: Contribution to conferencePaperpeer-review

    Abstract

    Rhynchosporiumcommune,thecausalagentofbarley scalddisease, poses amajor threat toglobal barleyproduction. Despite its significant impact, themolecularmechanisms underlyingR.commune’sinfectionprocessremainlargelyunexplored.To addressthis,weanalyzedthedifferentialgeneexpressiondataofR. communeWAI453 cultivatedunder both in planta and in vitro conditions, aiming to identify secondarymetabolitebiosynthetic geneclustersthatarepotentiallyinvolvedinthepathogenicityofR. commune. Our analysis revealed increased expression of a polyketide-terpene gene cluster (the rhy cluster), containing a specificmyeloblastosis(MYB)-typetranscriptionfactorgenerhyM, during in planta growth. Overexpressionof rhyMin an axenic cultureactivatedtheexpressionoftherhycluster,resultingintheproductionofaseriesofnewmeroterpenoidmetabolites,whichwe namedrhynchospenesA−E.TheirstructureswereelucidatedthroughacombinationofspectroscopicmethodsandsinglecrystalXray diffraction analysis. Infiltration of rhynchospenes into barley leaves resulted in strong necrosis, with rhynchospene B demonstratingthehighestphytotoxicityandcausingnecrosisataminimumconcentrationof50ppm.SilencingrhyMinR.commune WAI453confirmed the roleof rhynchospenes as virulence factors inbarleydisease.The resultingmutant showedsignificantly reducedexpressionof therhycluster inplantacomparedtothewild-typestrainanddecreasedvirulenceinseedlingpathogenicity assaysonbarley.Thecharacterizationoftherhyclusterandrhynchospenesprovidedinsightsintotheroleofsecondarymetabolites inR.communevirulenceandbarleyscalddiseasedevelopment.ThestudyalsohighlightsthepotentialuseofMYB-typetranscription factoroverexpressioninuncoveringcrypticSMs involvedinpathogenicityandhostadaptations.
    Original languageEnglish
    DOIs
    Publication statusPublished - 2025

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