Changes in DNA methylation contribute to rapid adaptation in bacterial plant pathogen evolution

Area of Science:

• Microbiology
• Epigenetics
• Plant Pathology

Background:

• Genetic mutations are the traditional explanation for adaptation.
• Epigenetic inheritance, including DNA methylation, is increasingly recognized as a factor in adaptation.
• The role of epigenetics in bacterial adaptation to new hosts requires further investigation.

Purpose of the Study:

• To investigate the role of DNA methylation in the adaptation of Ralstonia pseudosolanacearum to different plant hosts.
• To identify specific epigenetic modifications associated with adaptation during experimental evolution.

Main Methods:

• SMRT-seq technology was used to analyze methylomes of experimentally evolved Ralstonia pseudosolanacearum clones.
• Differential methylation sites (DMSs) were identified by comparing evolved clones to an ancestral clone.
• Gene expression analysis and site-directed mutagenesis were employed to validate findings.

Main Results:

• Fifty differential methylated sites (DMSs) at the GTWWAC motif were identified.
• Limited correlation was observed between differential methylation and gene expression, except for the RSp0338 gene.
• Two DMSs upstream of RSp0338 were confirmed and shown to contribute to host adaptation.

Conclusions:

• DNA methylation plays a significant role in the rapid adaptation of Ralstonia pseudosolanacearum to plant hosts.
• Early and stable epigenetic changes can facilitate both short-term and long-term adaptation.
• This study provides the first direct evidence linking bacterial epigenetic variation to adaptation in a new environment.