Genetic basis for repeated evolution of compound leaves over deep time

Area of Science:

• Evolutionary Biology
• Genomics
• Plant Science

Background:

• Convergent evolution of complex traits often involves diverse molecular pathways.
• Repeated evolution of compound leaves across angiosperms spans over 160 million years.

Purpose of the Study:

• To identify a shared genetic mechanism for the recurrent evolution of compound leaves in angiosperms.
• To investigate the role of gene family evolution in morphological innovation.

Main Methods:

• Macroevolutionary analysis of leaf forms in over 44,000 angiosperm species.
• Comparative genomic analysis of 414 high-quality plant genomes.
• Functional assays of KNOTTED1-like HOMEOBOX (KNOX) gene subclasses.

Main Results:

• At least 54 independent origins of compound leaves were identified across 63 families.
• KNOX gene family consistently expanded in compound-leaved lineages, primarily via whole-genome duplications (WGDs).
• KNOXI/KNOXM promote compound leaf development, while KNOXII suppresses it, explaining exceptions.

Conclusions:

• Preferential retention of KNOXI/M subfamilies after WGD is a recurrent mechanism for compound leaf evolution.
• This study links ancient genome duplications to repeated morphological innovation in flowering plants.
• A rare exception in Fabaceae highlights alternative genetic pathways (LEAFY) for compound leaf development.