Genomic Analysis Highlights Putative Defective Susceptibility Genes in Tomato Germplasm

Area of Science:

• Plant Pathology and Genetics
• Agricultural Science
• Molecular Biology

Background:

• Tomato (Solanum lycopersicum L.) is a globally important crop vulnerable to diseases causing significant yield loss.
• Developing disease resistance is crucial for improving tomato cultivation and ensuring food security.
• Plant susceptibility (S) genes facilitate pathogen interaction; mutations in these genes can confer broad-spectrum resistance.

Purpose of the Study:

• To conduct a genome-wide analysis of tomato genotypes to identify defective S-gene alleles for disease resistance breeding.
• To discover naturally occurring mutations in key susceptibility genes that can be leveraged for crop improvement.

Main Methods:

• Genome-wide analysis of 360 tomato genotypes, focusing on 125 homologs of 10 known S-genes.
• Identification and annotation of SNPs/indels using the SNPeff pipeline.
• Validation of high-impact mutations and subsequent infection assays with Oidium neolycopersici.

Main Results:

• Over 54,000 SNPs/indels were identified, with 120 high-impact variants (missense, nonsense, frameshift).
• 103 genotypes carried at least one high-impact mutation; 10 genotypes had more than 4.
• Two tomato genotypes with homozygous high-impact S-gene mutations showed significantly reduced susceptibility to Oidium neolycopersici.

Conclusions:

• Naturally occurring mutations in tomato S-genes represent a valuable resource for breeding disease-resistant varieties.
• Identified mutations provide a basis for understanding plant-pathogen interactions and developing durable resistance.
• These findings support the use of existing mutations in risk assessments for new genomic techniques in agriculture.