Stochastic gene expression drives mesophyll protoplast regeneration

Area of Science:

• Plant biology
• Cellular reprogramming
• Developmental biology

Background:

• Cell pluripotency is crucial for biological development.
• Differentiated somatic plant cells can regain pluripotency, a process vital for plant regeneration and gene transformation via isolated mesophyll protoplasts.
• The precise mechanisms governing plant cell reprogramming remain largely unknown.

Purpose of the Study:

• To identify genetic factors that promote the regeneration of isolated plant protoplasts.
• To elucidate the cellular and molecular changes induced by protoplast isolation that facilitate regeneration.
• To understand the role of gene expression variability and chromatin accessibility in cellular reprogramming.

Main Methods:

• Ectopic activation of candidate transcription factors.
• Protoplast isolation and regeneration assays.
• Live imaging and single-cell transcriptomics.
• Chromatin accessibility assays (e.g., ATAC-seq).

Main Results:

• Identified two transcription factors that significantly enhance protoplast regeneration upon ectopic activation.
• Protoplast isolation induces low-frequency, yet significant, expression of these factors.
• Single-cell transcriptomics revealed increased genome-wide expression variation and chromatin accessibility post-isolation.
• These changes promote stochastic gene activation, enhancing the regeneration potential of protoplasts.

Conclusions:

• Ectopic activation of specific transcription factors can drive plant protoplast regeneration.
• Protoplast isolation acts as a stressor, inducing a state of 'transcriptome chaos' characterized by increased gene expression variability and chromatin accessibility.
• This cellular reprogramming mechanism, driven by enhanced variability, may act as an evolutionary driver selecting for regenerating cells.