Proceedings of the National Academy of Sciences of the United States of AmericaApr 30, 2026

Removing a specific cell enzyme in maize helps resist lethal necrosis disease

CRISPR Gene Editing Weekly Brief ↗PubMed ↗DOI ↗OA ↗

Updated Jun 27, 2026

Abstract

Essence

Knocking out the maize MLNS1 peroxisomal peptidase conferred field resistance to maize lethal necrosis in an elite susceptible line.

Evidence

A fine-mapping, CRISPR-Cas9 editing, localization, and field-trial study linked the qMLNS1 locus to Mlns1 and showed that targeted knockout in CML536 blocked MCMV accumulation while preserving SCMV and disease-free agronomic performance.

Caveat

The resistance was demonstrated for edited maize lines in the studied field-trial context and specifically affected MCMV accumulation, so broader durability across germplasm, environments, and viral combinations remains untested in the abstract.

Simplified

Maize lethal necrosis (MLN) is a severe disease caused by the combined infection of maize chlorotic mottle virus (MCMV) and a potyvirus, most often sugarcane mosaic virus (SCMV). This disease seriously threatens food security across sub-Saharan Africa (SSA). We investigated a major-effect quantitative trait locus for resistance on chromosome 6, named the(), derived from the Thai line KS23-6. Fine mapping and CRISPR-Cas9 editing of the candidate genes within the narrowed 105 kb interval revealed a peroxisomalas the underlying cause of susceptibility. Confocal microscopy confirmed the localization of the MLNS1 protein within peroxisomes. Targeted knockout of thegene in the susceptible elite line CML536 from SSA conferred resistance comparable to KS23-6 in field trials conducted in Naivasha, Kenya. This knockout specifically blocked MCMV accumulation without affecting SCMV. The edited lines showed no yield penalty or agronomic defects under disease-free conditions. Our findings uncover a mechanistic link between a peroxisomal enzyme and viral susceptibility. They also establish a rapid, scalable gene editing strategy for incorporating MLN resistance into elite germplasm, offering a model for combating similar viral diseases in staple crops globally. maize lethal necrosis susceptibility locus 1qMLNS1peptidase Mlns1