EMS mutagenesis platform for developing diflufenican-resistant pigeon pea

Overview

Broadleaf weeds are the primary constraint on pigeon pea production, causing up to 80% yield loss in affected fields. Diflufenican (Broadal®) is a highly effective herbicide against a wide range of broadleaf weeds, but it is lethal to pigeon pea, limiting its use in this crop. This project applies ethyl methanesulfonate (EMS) mutagenesis to elite pigeon pea seed to generate a mutant population that can be screened for diflufenican resistance. The resulting resistant cultivars would allow growers to deploy diflufenican for weed control without damaging the crop, directly addressing a major agronomic bottleneck.

The approach builds on a well-established track record of mutation breeding for herbicide resistance, including imidazolinone-tolerant maize, wheat, rice, oilseed rape, and sunflower, as well as glyphosate-resistant soybeans. Prior EMS work in pigeon pea has already produced selectable variation in yield and morphological traits, indicating that herbicide-resistance traits are likely recoverable through this method.

Technical specifications

Key features:

• EMS mutagenesis pipeline applied to seed from elite pigeon pea cultivars to generate large mutant populations
• Kill curve optimization to determine the EMS concentration that achieves approximately 50% seedling germination efficiency, balancing mutation density with seedling viability
• High-throughput herbicide screening using seedling assays on diflufenican-containing media to select surviving mutants
• Field evaluation of surviving lines for agronomic performance, including growth rate, tillering, yield, and flowering characteristics
• Bioinformatic analysis to characterize the genetic basis and mechanism of any observed resistance
• Crop focus: pigeon pea (Cajanus cajan), a key pulse crop where broadleaf weed competition is the dominant yield constraint

Technology readiness level

The project is at an early experimental stage. A kill curve experiment to define the optimal EMS treatment concentration is planned, followed by large-scale seed mutagenesis and seedling screening on diflufenican. Resistant seedlings will be advanced to field trials for agronomic assessment, and bioinformatic work will run in parallel to identify the resistance mechanism. The pipeline draws on validated precedents in other crops, but no diflufenican-resistant pigeon pea line has yet been produced. Current readiness is best described as early-stage research and proof-of-concept development, with commercial deployment several breeding cycles away.