Discovery and Transmission of EMS-Induced Mutations in Chimeric Cucumber and Tomato

Reverse genetic screening of mutant populations for allelic variants has been successfully applied to many important crop species. First generation (M1) plants from mutagenized seed are chimeric, which makes mutation discovery difficult and unreliable; therefore, screening is usually done in the second generation (M2). This research demonstrates the development of “Purpose-built” mutant populations that are screened in the chimeric M1 generation. Cucumis sativus (cucumber) and Solanum lycopersicum (tomato) populations generated from 0.4% EMS mutagenized seeds were strategically pruned to reduce chimerism, then screened using Deep Variant Scanning (DVS), a high-fidelity Next-generation sequencing (NGS) and High-resolution melting (HRM) based mutation discovery platform. Mutation density for cucumber and tomato were 6.76 and 6.33 mutations/ Mb, respectively. Mutation transmission from M1 parents to progeny was 78% successful in cucumber and 33% successful in tomato. This method has broad applicability and can serve as an alternative to mutation breeding programs that use a permanent germplasm collection.