In the model plant Arabidopsis thaliana, parental age is known to affect somatic mutation rates in their immediate progeny, and this work demonstrates that this age-dependent effect persists across successive generations also. Using a set of detector lines carrying the mutated uidA gene, a study was carried out to ascertain 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 reversions was assessed in seedlings as a function of identical/different parental ages across generations. In the context of a fixed parental age, BSR/ICR rates were unaffected in the first three generations, then dropped significantly in the 4th and increased in most instances in the 5th generation (e.g. BSR (F1 38 =0.9, F2 38 =1.14, F3 38 =1.02, F4 38 = 0.5, F5 38= 0.76)). On the other hand, with advancing parental ages , BSR/ICR rates remained high in the first two/three generations, with a striking resemblance in the pattern of mutation rates (BSR (F1 38 =0.9, F1 43 =0.53, F1 48 =0.79, F1 53 =0.83 and F2 38 =1.14, F2 43 =0.57, F2 48 =0.64, F2 53 =0.94). A novel approach was adopted to identify and tag flowers pollinated on a particular day, thereby avoiding biases due to potential emasculation-induced stress responses. The 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.


Publication:
1. S. Bhushan, A. K. Singh, Y. Thakur, R. Baskar (2023) Persistence of parental age effect on somatic mutation rates across generations in Arabidopsis. BMC Plant Biology. 23:152