System drift in the evolution of plant meristem development

Area of Science:

• Evolutionary biology
• Developmental biology
• Genetics

Background:

• Developmental system drift (DSD) describes conserved phenotypes with changing genetic bases.
• Its prevalence in complex systems like developmental pattern formation is debated.
• Plant meristem development involves complex gene regulatory networks (GRNs).

Purpose of the Study:

• To investigate the occurrence and mechanisms of DSD in complex developmental GRNs.
• To model the evolution of GRNs governing plant meristem development.

Main Methods:

• A multi-scale computational model of GRN evolution was developed.
• Analysis of conserved non-coding sequences and gene expression patterns from public datasets.
• Simulations tracked changes in regulatory interactions over evolutionary time.

Main Results:

• Regulatory interactions essential for stem cell niche gene expression were initially conserved.
• These interactions were later lost and compensated by changes elsewhere in the GRN, indicating cis-regulatory rewiring.
• Frequent changes in conserved non-coding sequences were observed across plant species, uncorrelated with gene expression changes.

Conclusions:

• Developmental system drift is pervasive in the evolution of complex developmental systems.
• GRNs exhibit continual cis-regulatory rewiring, with conserved elements being gained and lost.
• Observed patterns in plant species support the model's findings on DSD in development.