BIOLOGICAL CONVERSION OF POTATO SPINDLE TUBER VIROID (PSTVD) RNA INTO NONINFECTIOUS ENTITY BY A SINGLE BASE SUBSTITUTION IN NICOTIANA BENTHAMIANA VAR DOMIN

Abstract

It is matter of common understanding that when we inoculate some strain of pathogen to model plant, it moves from source to sink. The Potato spindle tuber viroid (PSTVd) was first identified viroid of family Pospiviroidae, was isolated from Potato leaves i.e. natural host and submitted to Genebank (Accession # MK303578). The PSTVd is a single stranded circular RNA having 359 nucleotides which causes mild to severe symptoms in experimental host. Nicotiana benthamiana was selected as model targeted host and inoculated with mutated PSTVd (at base position 171). A single base change created at base position 171 of loop motif ‘26’ from A to U (T) has stopped PSTVd replication and make it noninfectious The RNA was extracted from host and converted into cDNA and sequenced again. The inoculated plant with a single base change showed no infection. No infection symptoms on experimental host plant.. The results of sequencing and BLAST and Mfold (version 3.0) confirmed a single base change at position 171 of Loop 26 of PSTVd. This was a unique approach to change genetic sequence of PSTVd to minimize/stop its infection and spread.