Persistence of parental age effect on somatic mutation rates across generations in Arabidopsis

Abstract

In the model plant Arabidopsis thaliana, parental age is known to affect somatic mutation rates in their immediate progeny but it is not clear if this age-associated effect on mutation rates persist across successive generations. Using a set of detector lines carrying the mutated uidA gene, we examined if a particular parental age maintained across five consecutive generations affected the rates of base substitution (BSR), intrachromosomal recombination (ICR), frameshift mutation (FS), and transposition. The frequency of functional GUS (blue colored spots) reversions were examined in seedlings as a function of identical/different parental ages across generations. When parental age remained constant, no change was observed in BSR/ICR rates in the first three generations, following which it drops significantly in the 4th and in most instances, is elevated in the 5th generation. On the other hand, with advancing parental age, BSR/ICR rates respectively remained high in the first two/three generations with a striking resemblance in the pattern of mutation rates. We followed a novel approach of identifying and tagging flowers pollinated on a particular day, thereby avoiding possible emasculation induced stress responses, as it may influence mutation rates. By and large there is no correlation in the expression of candidate genes involved in DNA repair to the pattern of reversion events and possibly, the expression patterns may correspond to the genomewide somatic mutations rates. Our results suggest a time component in counting the number of generations a plant has passed through self-fertilization at a particular age in determining the somatic mutation rates.

ATAC-seq: A powerful tool for investigating chromatin accessibility and transcription factor binding

“…Eukaryotic chromosomes are made up of bead-like nucleosomes that are folded and coiled in a helical pattern [1], with the DNA and histones wrapped around the nucleosomes [2,3]. Within chromosomes, most of the highly ordered packaging of DNA is not open, and only open DNA can undergo replication, transcription and translation for gene expression [4]. During transcription, some of the higher-order structure of the DNA is unwound, leaving the region accessible to transcription factors and other regulatory elements that can bind to it and facilitate transcription [5].…”