Optimized breeding strategies for multiple trait integration: II. Process efficiency in event pyramiding and trait...

Area of Science:

• Plant breeding
• Genetics
• Agricultural biotechnology

Background:

• Multiple Trait Integration (MTI) is crucial for enhancing elite crop varieties with value-added traits via backcross breeding.
• MTI involves sequential steps: single event introgression, event pyramiding, trait fixation, and version testing.
• Optimizing event pyramiding and trait fixation is key to efficient MTI for elite maize hybrids.

Purpose of the Study:

• To optimize breeding strategies for pyramiding multiple transgenic events into maize recurrent parents (RPs).
• To identify efficient methods for trait fixation, ensuring homozygosity for all integrated events.
• To evaluate breeding strategies based on efficiency indicators like time, resources, and seed requirements.

Main Methods:

• Utilized computer simulation and probability theory to devise optimal breeding strategies.
• Developed a symmetric crossing schedule for pyramiding eight (or seven) events into female (or male) RPs.
• Compared selfing (including 'F2 enrichment') and doubled haploid approaches for trait fixation, incorporating seed chipping and tissue sampling for genotyping.

Main Results:

• A symmetric crossing schedule was devised for efficient event pyramiding.
• The combination of seed chipping and a two-generation selfing approach (SC + SELF) was identified as the most efficient strategy.
• Doubled haploidy showed limited utility for trait fixation in this specific MTI scenario.

Conclusions:

• The SC + SELF strategy offers the most efficient approach for trait fixation in MTI, balancing time to market and resource utilization.
• Optimized strategies for event pyramiding and trait fixation streamline the MTI process, paving the way for efficient version testing.
• This research provides a practical framework for accelerating the development of multi-event converted elite maize hybrids.