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A maize enzyme from the 2-oxoglutarate-dependent oxygenase family with unique kinetic properties, mediates resistance against pathogens and regulates senescence
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  • Paula Casati,
  • Paloma Serra,
  • Silvana Righini Aramburu,
  • Julieta Petrich,
  • Valeria Campos Bermudez,
  • Maria Falcone Ferreyra
Paula Casati
Centro de Estudios Fotosinteticos y Bioquimicos

Corresponding Author:casati@cefobi-conicet.gov.ar

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Paloma Serra
Centro de Estudios Fotosinteticos y Bioquimicos
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Silvana Righini Aramburu
Centro de Estudios Fotosinteticos y Bioquimicos
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Julieta Petrich
Centro de Estudios Fotosinteticos y Bioquimicos
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Valeria Campos Bermudez
Centro de Estudios Fotosinteticos y Bioquimicos
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Maria Falcone Ferreyra
Centro de Estudios Fotosinteticos y Bioquimicos
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Abstract

In plants, salicylic acid (SA) hydroxylation regulates SA homoeostasis, playing an essential role during plant development and response to pathogens. This reaction is catalyzed by SA hydroxylase enzymes, which hydroxylate SA producing 2,3- dihydroxybenzoic acid (2,3-DHBA) and/or 2,5-dihydroxybenzoic acid (2,5-DHBA). Several SA hydroxylases have been recently identified and characterized from different plant species; however, no such activity has been previously reported in maize. In this work, we describe the identification and characterization of a new SA hydroxylase in maize plants. This enzyme, with high sequence similarity to previously described SA hydroxylases from Arabidopsis and rice, converts SA into 2,5-DHBA; however, it shows different kinetics properties to those from previously characterized enzymes, and it also catalyzes the conversion of the flavonoid dihydroquercetin into quercetin in in vitro activity assays, suggesting that the maize enzyme may have different roles in vivo as those previously reported from other species. Despite this, ZmS5H can complement the resistance to pathogen and early senescence phenotypes of Arabidopsis s3h mutant plants. Finally, we characterized a maize mutant in the S5H gene ( s5hMu) that has altered growth, senescence and increased resistance against Colletotrichum graminicola infection, showing not only changes in SA and 2,5-DHBA but also variations in flavonol levels. Together, the results presented here provide evidence that SA hydroxylases in different plant species have evolved to show differences in catalytic properties that may be important to fine tune SA levels and other phenolic compounds such as flavonols to regulate different aspects of plant development and defense against pathogens.
13 Oct 2023Submitted to Plant, Cell & Environment
13 Oct 2023Submission Checks Completed
13 Oct 2023Assigned to Editor
15 Oct 2023Review(s) Completed, Editorial Evaluation Pending
16 Oct 2023Reviewer(s) Assigned
16 Nov 2023Editorial Decision: Revise Minor
24 Jan 2024Editorial Decision: Revise Minor
11 Apr 2024Submission Checks Completed
11 Apr 2024Assigned to Editor
11 Apr 2024Review(s) Completed, Editorial Evaluation Pending
16 Apr 2024Editorial Decision: Accept