Powdery Mildew Resistance in Melon via CRISPR/Cas9 Genome Editing

Overview

Powdery mildew is one of the most damaging diseases affecting melon (Cucumis melo) production, yet disease-resistant cultivars remain uncommon due to the difficulty of conventional resistant plant breeding. This project addresses that challenge by applying CRISPR/Cas9 genome editing to introduce targeted mutations in specific members of the MLO gene family, which is highly conserved across Cucumis species. Loss-of-function mutations in certain MLO genes have been associated with broad-spectrum powdery mildew resistance in other crops, making this a promising route for melon improvement. The work combines bioinformatics-driven target identification, CRISPR/Cas9 editing, and single-walled carbon nanotube (SWCNT)-mediated plant transformation to produce mutant melon lines with durable disease resistance.

Technical specifications

• Target identification: Three candidate MLO genes for powdery mildew resistance in melon were identified through whole-genome bioinformatic analysis of Cucumis melo and related gene family members in close relatives.
• CRISPR/Cas9 design: Multiple sgRNAs were designed for each candidate gene, with cloning strategies established for construct assembly.
• Tissue culture foundation: In vitro culture protocols for Cucumis melo have been optimized across several commercial varieties, covering micropropagation, callus formation, and plant regeneration.
• Transformation methods: Beyond conventional biolistics and Agrobacterium approaches, the project employs single-walled carbon nanotubes (SWCNTs) for DNA delivery into plant cells.
• Validation pipeline: Includes protoplast transformation for transient expression checks, stable transformation via SWCNTs, mutation confirmation by sequencing, off-target analysis through whole-genome sequencing, and qPCR-based expression and functional pathogen resistance assays.
• Statistical rigor: Each experiment is planned with at least three replicates.

Technology readiness level

The project is at an early-to-intermediate stage of development. Tissue culture optimization and bioinformatic target identification are complete, and CRISPR construct design and cloning are underway. Plant transformation protocols are being optimized. Remaining work includes callus formation and regeneration, protoplast validation, stable transformation with SWCNTs, mutant plant regeneration, off-target mutation screening, and functional pathogen resistance testing. The full study is expected to take approximately two years. The team is seeking partnership support for transformation studies, whole-genome sequencing, and functional analysis for pathogen resistance.