The widespread use of gene silencing against specific endo-genes in plants and animals is in practice. Different methods are used for triggering gene suppression in plants and animals.  Peach Eg4 was targeted through small interfering RNA (siRNA) for down-regulation which belongs to the EGase family and encodes 1-4-beta-glucanase enzyme in fruit mesocarp, responsible for early softening of mesocarp. A 22-nucleotides (22-nts) siRNA was designed and synthesized in vitro within the Eg4 gene with 2-nts overhangs at 3^/ and injected into the peach leaves. Two months later total RNA was isolated from leaves and fruit pulps and analyzed through northern blotting where the 22-nts siRNA was detected. The mRNA of Eg4 was also probed in the extracts and the results were compared with control samples of leaves and fruits. The presence of Eg4 mRNA was confirmed in untreated samples while the 22-nts siRNA were not detected. The samples isolated from the treated plants lack Eg4 mRNA and contained the 22-nts siRNAs. The contemporary presence of Eg4 mRNA and 22-nts siRNAs were not observed which proves that the presence of siRNA was responsible for the triggering of homology-based degradation of the target mRNA. The experiments were repeated the next year and the same results were obtained. It was concluded from the results that siRNA injected in the leaves is amplified through RNA dependent RNA polymerase (RdRp) and spread systemically in the plant tissues, therefore siRNA injection can be used as a sustainable means for endo-gene silencing.

Keywords: dsRNA, gene silencing, Prunus persica, siRNA injection