Leaf shape in Populus tremula is a complex, omnigenic trait.

Area of Science:

• Plant genetics
• Evolutionary biology
• Genomics

Background:

• Leaf shape is crucial for plant classification and exhibits significant variation within species.
• Understanding the genetic basis of leaf shape variation is essential for plant breeding and evolutionary studies.

Purpose of the Study:

• To characterize the genetic architecture of leaf shape variation in Eurasian aspen (Populus tremula).
• To identify candidate genes underlying leaf shape diversity and their regulatory mechanisms.

Main Methods:

• Genome-wide association study (GWAS) for leaf physiognomy traits in Populus tremula.
• RNA-Seq and gene co-expression network analyses during leaf development.
• Integration of population-wide expression data, eQTL analysis, and differential gene expression analysis.

Main Results:

• Leaf shape variation is genetically complex, likely controlled by numerous small-effect gene expression variations.
• Genes associated with leaf shape were peripheral in co-expression networks and showed signatures of relaxed selection.
• No clear adaptive significance was identified for the observed leaf shape variation.

Conclusions:

• Leaf shape in Eurasian aspen is a complex trait influenced by polygenic effects on gene expression.
• The genetic architecture of leaf shape variation is consistent with the omnigenic model, suggesting widespread gene expression regulation.
• The findings provide insights into the evolutionary processes shaping plant morphology.