# Histone Deacetylase 19 Controls Powdery Mildew Susceptibility by Attenuating Biosynthesis of Cuticular Wax and Salicylic Acid

## TL;DR

A wheat enzyme called TaHDA19 makes the plant more vulnerable to powdery mildew by reducing protective waxes and a key chemical signal.

## Contribution

TaHDA19 is newly identified as a regulator of wheat susceptibility to powdery mildew through epigenetic control of wax and salicylic acid.

## Key findings

- Knockdown of TaHDA19 increases cuticular wax and salicylic acid, reducing powdery mildew susceptibility.
- TaHDA19 suppresses TaECR and TaSARD1 transcription via histone deacetylation.
- Cuticular wax and salicylic acid act as chemical cues affecting wheat's resistance to Blumeria graminis.

## Abstract

Phytopathogenic Ascomycetes Blumeria graminis f. sp. tritici (Bgt) causes wheat powdery mildew disease and impacts global wheat production. Decoding the molecular wheat-Bgt interaction could facilitate the wheat disease resistance breeding. In this study, we elucidated that wheat histone deacetylase 19 (TaHDA19) regulates susceptibility to Bgt pathogen by suppressing biosynthesis of cuticular wax and salicylic acid (SA). Knockdown of wheat TaHDA19 gene expression led to in enhanced cuticular wax and SA accumulation, potentiated Bgt conidia germination and appressoria formation, attenuated formation of Bgt haustoria and microcolonies. Histone deacetylase TaHDA19 is enriched at the TaECR and TaSARD1 promoter regions to facilitate histone deacetylation, and thus suppressing TaECR and TaSARD1 transcription. In addition, we identified cuticular wax and SA regulated by TaHDA19 as chemical cues determining wheat pre- and postsusceptibility to Bgt pathogen. These findings collectively support that the wheat histone deacetylase TaHDA19 epigenetically suppresses cuticular wax and SA biosynthesis, thereby dampening chemical cues essential for the wheat powdery mildew susceptibility.