# A pathogen-induced translational shift enhances plant disease resistance without obvious fitness costs

## TL;DR

This study shows how plants can boost disease resistance without harming their growth by using a clever translation control mechanism.

## Contribution

A novel strategy for inducible resistance gene expression using a translational shift in the 5ʹ UTR of PI4KIII β1.

## Key findings

- The 5ʹ UTR of PI4KIII β1 shifts translation initiation during immune activation.
- HIR1 expression driven by this cassette enhances disease resistance in Arabidopsis.
- No significant fitness costs were observed in transgenic plants.

## Abstract

Exploring immune mechanisms in plants opens new avenues for engineering disease resistance in crops. Approaches such as the ectopic expression of resistance genes are frequently associated with fitness costs, rendering the resulting germplasm less desirable for agricultural applications. Inducible production of resistance factors is one potential workaround for this problem. In this study, we determined that the 5ʹ untranslated region (5ʹ UTR) of Arabidopsis (Arabidopsis thaliana) PI4KIII β1 undergoes a translational shift that alters its translation initiation site upon the activation of immunity. Based on this discovery, we developed a PI4KIII β1 5ʹ UTR cassette to specifically regulate the expression of the hypersensitive induced reaction gene HIR1, which encodes a cell death-inducing protein. Under normal conditions, ribosomes initiated translation from the first start codon in the PI4KIII β1 5ʹ UTR cassette; however, upon pathogen challenge, the ribosomes bypassed this site and instead initiated translation from a downstream start codon, enabling HIR1 expression. Transgenic Arabidopsis plants harboring the PI4KIII β1 5ʹ UTR cassette driving HIR1 exhibited enhanced disease resistance without detectable changes in key agricultural traits. Therefore, precisely regulating translation initiation through leaky ribosome scanning represents a promising strategy for developing pathogen-resistant crops without obvious fitness costs.