Work

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

Year: 2026

Type: preprint

Abstract: Summary 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.

Source: bioRxiv (Cold Spring Harbor Laboratory)

DOI: 10.64898/2026.09.02.748781