TALE-independent transcriptional activation of the rice executor gene Xa23 is regulated via histone acetylation during zygote development

Schenstnyi, K.; Rattanawong, K.; Satoh, A.; Strauss, A.; Faiss, N.; Holmes, D. R.; Redzich, L.; Toda, E.; Aini, H.; Kinoshita, A.; Lahaye, T.; Okamoto, T.

doi:10.64898/2026.09.02.748781

bioRxiv · 10.64898/2026.09.02.748781

TALE-independent transcriptional activation of the rice executor gene Xa23 is regulated via histone acetylation during zygote development

Schenstnyi, K.·Rattanawong, K.·Satoh, A.·Strauss, A.·Faiss, N.·Holmes, D. R.·Redzich, L.·Toda, E.·Aini, H.·Kinoshita, A.·Lahaye, T.·Okamoto, T.

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Abstract

Transcription activator-like effectors (TALEs) from Xanthomonas activate transcription of executor (E) genes in host plants, leading to cell death and thereby restricting proliferation of biotrophic pathogens. Because E gene transcripts had only been detected upon activation by cognate Xanthomonas TALEs, E genes were thought to function exclusively in plant immunity. Here, we detect TALE-independent transcription of the rice E gene Xa23 in zygotes 4-6 hours after gamete fusion. Histone deacetylase inhibition induces Xa23 transcription in unfertilized egg cells, implicating histone acetylation in Xa23 regulation. We identified potential cis-regulatory elements and transcription start sites associated with native Xa23 transcription during zygote development. Together, our findings suggest that Xa23 is a developmentally regulated gene with a native role during early zygote development. This supports a previously proposed model in which E genes have native functions in development, while fortuitous upstream polymorphisms can create TALE-binding sites that convert them into immune executors.

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Schenstnyi, K., Rattanawong, K., Satoh, A., Strauss, A., Faiss, N., Holmes, D. R., Redzich, L., Toda, E., Aini, H., Kinoshita, A., Lahaye, T., Okamoto, T.. 2026-09-03. TALE-independent transcriptional activation of the rice executor gene Xa23 is regulated via histone acetylation during zygote development. https://doi.org/10.64898/2026.09.02.748781

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