Describe RNA editing in plants.

Explanation

(i) Chemical modification such as base modification, nucleotide insertion or deletions and nucleotide replacements of mRNA results in the alteration of amino acid sequence of protein that is specified is called RNA editing. This results in the change in the protein ~oding sequence of RNA following transcription. The coding properties of the RNA transcript is changed. The genetic information encoded in the chloroplast genome is altered by post transcriptional phenomenon which is site - specific (C `rarr` U) in chloroplast of higher plants - RNA editing occurs in plant mitochondria and chloroplast.
(ii) In plant cells RNA editing by pyrimidine transitions occurs in mitochondria and plastids (chloroplast). There are two main types of RNA editing.
1. Substitution editing -Alteration of individual nucleotide bases. Mitochondria and chloroplast RNA in plants.
2. Insertion / Deletion editing - Nucleotides are added or deleted from the total number of bases.
Significancc of RNA editing
(a) In higher plant chloroplast, it helps to restore the codons for conserved aminoacids which include initiation and termination codon.
(b) It regulates organellar gene expression in plants.
(c) RNA editing results in the restoration of codons for phylogenetically conserved amino acid residues.