# Genome‐Edited Maize Expressing Two Native Genes Confers Broad‐Spectrum Resistance to Northern Corn Leaf Blight

## TL;DR

Scientists used genome editing to create maize plants resistant to a major leaf disease without affecting yield.

## Contribution

A novel resistance allele, NLB18-R, was identified and combined with Ht1-R using CRISPR-Cas9 to confer broad-spectrum resistance.

## Key findings

- Genome-edited maize plants showed resistance to Setosphaeria turcica races 0, 1, and 23N.
- Stacking NLB18-R and Ht1-R did not reduce yield compared to controls under disease-free conditions.

## Abstract

Northern corn leaf blight (NCLB) can result in yield losses of up to 50% in maize. The most effective strategy for managing NCLB is the deployment of resistant hybrids. Conventional breeding methods typically require 6 or 7 backcross generations to introgress a resistance locus, often bringing along undesirable traits that reduce yield. Recent advances in genome editing offer a precise alternative, enabling the targeted incorporation of resistance genes without linkage drag. In this study, we identified an NCLB resistance gene, NLB18‐R, that is allelic to Htn1 and Ht2/Ht3. Using CRISPR‐Cas9, we replaced the susceptible allele (NLB18‐S) with NLB18‐R in an elite inbred, resulting in enhanced resistance to NCLB. In a parallel experiment, we inserted both NLB18‐R and the resistance gene Ht1‐R into preselected, closely linked sites on chromosome 1. Through genetic crossing, we combined these edits into a stack. The resulting genome‐edited plants exhibited resistance to Setosphaeria turcica races 0, 1 and 23N. Field trials under disease‐free conditions showed no significant yield differences between hybrids carrying NLB18‐R, Ht1‐R, or the stack compared to null and wild‐type controls. These findings demonstrate that CRISPR‐Cas9‐mediated genome editing is a powerful tool for rapidly developing commercial‐grade maize hybrids with broad‐spectrum resistance to NCLB, and potentially other diseases.

We identified a novel resistance allele, NLB18‐R, at the Htn1 locus. Using CRISPR‐Cas9, we replaced the susceptible allele (NLB18‐S) with NLB18‐R in an elite inbred. We stacked NLB18‐R and the resistance gene Ht1‐R. The resulting genome‐edited plants exhibited resistance to Setosphaeria turcica races 0, 1 and 23N.