Pathogen Species-Specific Differences in Induction of the Maize Polyubiquitin Gene Promoter in Transgenic Wheat.

Saeid Babaei; Neil Smith; Chunhong Chen; Dhara Bhatt; Brenton Brooks; Jian Chen; Joshua Philips; Rohit Mago; Ming-Bo Wang; Ming Luo; Michael Ayliffe

doi:10.1094/mpmi-12-25-0174-r

PubMed · 42218787

Pathogen Species-Specific Differences in Induction of the Maize Polyubiquitin Gene Promoter in Transgenic Wheat.

Saeid Babaei·Neil Smith·Chunhong Chen·Dhara Bhatt·Brenton Brooks·Jian Chen·Joshua Philips·Rohit Mago·Ming-Bo Wang·Ming Luo·Michael Ayliffe

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Abstract

The maize polyubiquitin promoter (ZmUbi) is a mainstay in molecular biology for transgene expression and is used for constitutive expression of defense-related gene products. Transgenic wheat lines were produced expressing a ZmUbi-RUBY reporter gene that produces the red pigment betalain. Some lines showed transgene silencing with reduced RUBY transcript accumulation and chimeric sectors of betalain. Infection of these plants with Blumeria graminis, Puccinia graminis f. sp. tritici (Pgt), or P. triticina (Pt) each resulted in localized betalain accumulation at infection sites and increased RUBY transcript accumulation. In contrast, two isolates of P. striiformis f. sp. tritici (Pst) caused no detectable RUBY transcript accumulation and no visible betalain accumulation at infection sites, although a modest betalain increase was detected in infected tissue extracts. Compared with Pst, Pgt more strongly induced host genes involved in transcriptional and post-transcriptional regulatory processes, although no obvious pathogen-induced changes in ZmUbi promoter methylation were observed. ZmUbi-GUS transgenic wheat plants were also pathogen challenged, and, unlike Pst, both Pgt and Pt induced localized GUS staining at infection sites. Database mining showed that the endogenous maize polyubiquitin gene from which ZmUbi is derived was pathogen inducible, albeit in a species-specific fashion. These pathogen differences in ZmUbi induction have implications when using this regulatory element to express defense-related transgenes in wheat. Comparing the resistance efficacy of transgenes against different pathogens using this promoter is potentially influenced by significant, localized expression differences occurring at infection sites of different pathogen species. [Formula: see text] Copyright © 2026 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

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Promoter Regions, Genetic Plants, Genetically Modified Triticum Zea mays Polyubiquitin Plant Diseases Gene Expression Regulation, Plant Ascomycota Puccinia Plant Proteins Species Specificity Blumeria biotroph induction pathogen promoter ubiquitin Journal Article

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Saeid Babaei, Neil Smith, Chunhong Chen, Dhara Bhatt, Brenton Brooks, Jian Chen, Joshua Philips, Rohit Mago, Ming-Bo Wang, Ming Luo, Michael Ayliffe. 2026-07-22. Pathogen Species-Specific Differences in Induction of the Maize Polyubiquitin Gene Promoter in Transgenic Wheat.. https://doi.org/10.1094/mpmi-12-25-0174-r

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