Enhanced dsRNA-mediated resistance in zucchini against zucchini yellow mosaic virus by topical application of dsRNA deriving from the P1 gene

Abstract Crop protection against viruses is a challenging task and different approaches were developed that are environmentally friendly and safe for human and animal health. The non-transgenic dsRNA-mediated strategy exploiting the RNA interference (RNAi) has given very good results for the plant-virus pathosystems to which it has been applied. Previously, dsRNA for the helper-component (dsHC) of zucchini yellow mosaic virus (ZYMV) conferred a low 18% protection when applied in zucchini. Four dsRNAs derived from P1, P3, 6k2-VPg, and VPg cistrons of ZYMV were produced and topically applied on zucchini for a comparative analysis. All four dsRNAs protected the zucchini against ZYMV; the dsP1, dsP3, ds6k2, and dsVPg gave 62%, 21%, 25%, 25% protection, respectively, whereas dsHC gave only 16% protection. Therefore, topical application of dsP1, providing a high protection (62%) in zucchini against ZYMV, is a significant improvement in disease control. Comparison of the dsP1 with the amiZYMV_HC-196as (previously shown to convey 54% protection to ZYMV) indicated that both approaches/treatments provide high resistance in zucchini against ZYMV. Lastly, it is confirmed that dsHC, applied as root drenching, can be absorbed by roots, transported to leaves, and remained in leaves for more than six days depending on the cucurbit host.