Uniform Expression and Relatively Small Position Effects Characterize Sister Transformants in Maize and Soybean

Area of Science:

• Plant biotechnology
• Genomics
• Agricultural science

Background:

• Transgenic development for industrial, agricultural, or medicinal uses requires effective transgene expression without fitness costs.
• Genomic insertion site is crucial for successful transgene integration, but its effect on expression and fitness in plants remains under-explored.

Purpose of the Study:

• To systematically investigate the impact of transgene insertion site on transgene expression and plant fitness in maize and soybean.
• To compare the relative importance of genomic location against other factors influencing transgene expression.

Main Methods:

• Utilized random and site-specific transgene integration in maize and soybean.
• Evaluated 68 genomic sites for transgene expression levels and agronomic performance across generations and multiple field locations.
• Compared transgene expression influenced by genomic location, cis-regulatory elements, transgene neighbors, genetic background, and zygosity.

Main Results:

• Genomic location had the least impact on transgene expression compared to cis-regulatory elements and transgene neighbors.
• The majority of insertion sites supported statistically indistinguishable, high-level transgene expression, consistent across generations.
• Agronomic performance showed no to minimal decrease across most evaluated insertion sites in five maize hybrid backgrounds.

Conclusions:

• Genomic location is a less critical factor for achieving high transgene expression and maintaining crop performance than previously assumed.
• The majority of genomic sites in maize and soybean are suitable for transgene integration without negative consequences.
• Findings suggest greater flexibility in transgene design and development for agricultural applications.