Microsatellite instability in Arabidopsis increases with plant development

Area of Science:

• Plant Biology
• Genetics
• Molecular Biology

Background:

• Plant development involves cell division, endoreduplication, and growth, necessitating robust genome stability mechanisms.
• DNA repair and genome surveillance are crucial for maintaining genome integrity during plant development.
• Previous research indicated a decline in homologous recombination repair rates in older plants.

Purpose of the Study:

• To investigate age-dependent changes in DNA repair capacity in Arabidopsis.
• To analyze the causes of increased microsatellite instability in aging plants.
• To determine the contribution of various DNA repair pathways to age-related genomic instability.

Main Methods:

• Utilized transgenic Arabidopsis plants with microsatellite repeats in a nonfunctional gene.
• Assessed microsatellite instability across different plant ages.
• Analyzed DNA polymerase activity, fidelity, and expression levels of key DNA repair genes (Msh2, Msh6).
• Performed in vitro repair assays, specifically nonhomologous end joining (NHEJ).

Main Results:

• Microsatellite instability significantly increased with plant age.
• Total DNA polymerase activity decreased, while fidelity increased in older plants.
• Steady-state RNA levels of replicative polymerases and DNA repair proteins (Msh2, Msh6) decreased with age.
• Nonhomologous end joining (NHEJ) efficiency was lower in older plants, with increased Ku70 expression.

Conclusions:

• Age-dependent decline in DNA repair mechanisms contributes to increased microsatellite instability.
• Reduced mismatch repair activity and less efficient nonhomologous end joining are likely key factors.
• These findings highlight the impact of aging on plant genome stability and repair processes.