Question

While investigating a gene that might be responsible for pathogen resistance in the plant Arabidopsis, you discover that many of the nucleotides in the gene sequence are methylated.

(b) Draw the structure of this methylated nucleotide. Be sure to include all atoms and the necessary bonds to each atom of the phosphate, the sugar and the base in its methylated form.

(c) What might this methylation do to the function of this gene?

Answer 1

b

c) Mutation in regulators of DNA methylation or
demethylation can alter plant susceptibility to certain pathogens.

In Arabidopsis thaliana, the DNA demethylase REPRESSOR OF SILENCING 1 (ROS1) and its homologues TRANSCRIPTIONAL ACTIVATOR DEMETER (DME)-LIKE 2 (DML2) and DML3
collectively regulate many biotic stress-responsive genes by removing DNA methylation (m). Plants which do not encode these three demethylases show increased susceptibility to the fungal pathogen Fusarium oxysporum. Thus DNA methylation causes increased susceptibility to stress like salt tolerance.