Cell lineage dynamics in stratified shoot apical meristems

Area of Science:

• Plant developmental biology
• Computational biology
• Genetics

Background:

• The shoot apical meristem (SAM) is crucial for plant growth and development.
• Understanding cell dynamics and mutation effects within the SAM is key to plant genetics.
• Previous models did not fully account for the spatial organization of SAM initials.

Purpose of the Study:

• To develop a stochastic, spatially explicit model for initial cell dynamics in a stratified SAM.
• To investigate the fixation or purging probabilities of mutant lineages under selection and drift.
• To analyze the impact of SAM's functional organization on mutation dynamics.

Main Methods:

• Stochastic and spatially explicit modeling of cell dynamics.
• Simulation of mutant lineage behavior (fixation or purging).
• Analysis of mutation fixation probability and division numbers based on fitness.

Main Results:

• Stratified SAM organization acts as an efficient purging mechanism for deleterious mutations.
• Deleterious mutants are rapidly purged; fixation probability for beneficial mutants increases linearly up to 70%.
• Median divisions to fixation are largely insensitive to mutant fitness; long-lived chimeric stages occur if mutants overcome initial disadvantages.

Conclusions:

• The spatial organization of the SAM is critical for efficiently purging mutant lineages, especially deleterious ones.
• Beneficial mutations have a significant probability of fixation, influenced by the SAM's structure.
• The SAM's spatial arrangement impacts mutation dynamics, leading to rapid purging or prolonged chimeric stages.