Topical application of dsRNAs targeting Citrus tristeza virus (CTV) reduces its titer in the CTV infected sweet orange (Citrus sinensis)

Abstract

Citrus tristeza virus (CTV) is found worldwide wherever citrus is cultivated, causing Citrus tristeza disease resulting in significant yield losses and sometimes the death of the plant. Transgenic citrus plants encoding CTV gene sequences have shown to exhibit pathogen-derived resistance to CTV. Exogenous application of double-stranded RNA (dsRNA) is an established strategy for plant virus control, making this method an attractive alternative to transgenic RNA interference (RNAi). The dsRNA molecules targeting the CP, p20, and p23 genes of CTV G8 strain were synthesized in vitro and topically applied onto the leaves of sweet orange ( Citrus sinensis ) infected with CTV strain G8. The exogenous application of all the dsRNAs reduced CTV titer at 10 days post application (dpa) as revealed by quantitative RT-PCR assay done at four different time points. These results provide a proof-of-concept for a non-transgenic approach of controlling CTV, a closterovirus, in a perennial fruit crop such as citrus.

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