Spray-Induced Gene Silencing of SsOah1 and SsCyp51 confers protection to Nicotianabenthamiana and Brassicajuncea against Sclerotiniasclerotiorum

Abstract

Brassicajuncea is a major oilseed, vegetable and condiment crop in the Indian subcontinent. Its yields are compromised by the aggressive broad host range Ascomycete Sclerotiniasclerotiorum, which causes Sclerotinia Stem Rot (SSR). The limited effectiveness of fungicides, the rapid development of resistance to fungicides, and the long-term viability of sclerotia in the soil are crucial bottlenecks in controlling the disease. The discovery of the uptake of environmental RNA by fungal pathogens has opened up avenues for exploiting Spray-Induced Gene Silencing (SIGS) as a tool for mitigating plant diseases. We studied the impact of SIGS-based knockdown of S.sclerotiorumSsOah1 (SS1G_08218) and SsCyp51 (SS1G_04805), involved in virulence and fungal development, respectively, on two hosts- N.benthamiana and B.juncea. A knockdown of the two genes delayed disease initiation, reduced lesion development, and slowed disease progression within B.juncea. However, this silencing was concentration and host-dependent. Further, it also altered fungal hyphal morphology and growth, indicating its utility as a functional genomics tool. Our results identify SsCyp51 as a novel and viable target for SSR control along with SsOah1 and corroborate SIGS as a robust method for crop protection against broad-host-range fungal pathogens.