Controlling verticillium wilt in Acer mollo maxim with a star polycation dsRNA delivery system targeting Verticillium dahliae VDAG_03333

Abstract

Verticillium wilt, caused by the fungal pathogen Verticillium dahliae, poses a significant global economic threat due to its complex pathogenic mechanisms and its unclear interaction with host plants. These complexities are exacerbated by the pathogen's stable dormant structures, microsclerotia, and its long co-evolution with host plants. In this study, we explored the biological function of the chitin deacetylase gene VDAG_03333 from V. dahliae and developed a double stranded RNA (dsRNA) based on its coding sequence (CDS). This dsRNA was introduced into the roots of Acer mollo Maxim using a novel star polycation (SPc), which effectively mitigated Verticillium wilt. VDAG_03333 is not necessary for V. dahliae growth on potato dextrose agar, while deletion of it significantly reduced the sporulation and spore penetration abilities of V. dahliae, thereby diminishing its pathogenicity in two-week-old potted seedlings of Acer mollo Maxim. The optimal mass mixing ratio of dsRNA to SPc was established at 1:1. The SPc reduced the particle size of dsRNA from 702.87 ± 16.34 nm to 36.30 ± 2.93 nm and increased the zeta potential from +8.24 mV to +12.50 mV, enhancing the stability of dsRNA. Compared to its naked counterpart, the dsRNA/SPc complex further suppressed VDAG_03333 expression, reduced spore production and penetration, and improved access to the root tips of A. mollo. Consequently, the dsRNA/SPc complex provided superior protection against V. dahliae infection and demonstrated enhanced environmental sustainability over traditional pesticides. This study presents an environmentally friendly approach for managing severe plant pests and diseases.