Complex Trait Loci in Maize Enabled by CRISPR-Cas9 Mediated Gene Insertion

Area of Science:

• Agricultural Science
• Genetics and Genomics
• Biotechnology

Background:

• Modern maize hybrids incorporate numerous biotech and native traits.
• Current methods for inserting multiple traits are inefficient, costly, and complex due to random genome insertion.
• Developing maize with stacked traits is a significant challenge in crop improvement.

Purpose of the Study:

• To introduce a novel method for efficient trait stacking in maize using CRISPR-Cas9 technology.
• To develop a complex trait locus (CTL) for targeted insertion of multiple genes.
• To overcome the limitations of random gene insertion in creating multi-trait maize hybrids.

Main Methods:

• Utilized CRISPR-Cas9 gene editing to engineer a complex trait locus (CTL) in maize.
• Generated individual maize lines with site-specific insertion landing pads (SSILPs) at preselected sites within the CTL.
• Employed recombinase-mediated cassette exchange for efficient transgene insertion into SSILPs.

Main Results:

• Successfully generated maize lines with SSILPs at targeted sites within the CTL.
• Demonstrated consistent transgene expression from selected insertion sites.
• Confirmed that SSILP insertion did not negatively impact grain yield.
• Showcased the ability to combine two traits at different CTL sites via genetic recombination.

Conclusions:

• CTL technology offers a streamlined and efficient approach for developing multi-trait maize hybrids.
• This method significantly reduces the complexity and cost associated with trait stacking.
• CTL represents a major advancement in the genetic engineering of maize for improved crop performance.