Silencing of the MP Gene via dsRNA Affects Root Development and Growth in the Invasive Weed Mikania micrantha

("mile-a-minute" weed) is a global invasive alien weed that can cause severe damage to agroforestry ecosystems and significant agricultural losses worldwide. Although chemical, manual, or mechanical control methods are widely used to control , RNA interference (RNAi)-based biocontrol methods have rarely been reported for this species. The ( ) gene, encoding an auxin response factor, plays an essential role in embryonic root initiation in . In this study, we identified the gene from via orthologous gene analysis. A total of 37 orthologous genes was identified in 4 plants, including 9 candidate genes in , 13 in , 6 in , and 9 in . Phylogenetic analysis revealed that an candidate gene in named ) was clustered into one clade with the gene in ( ). In addition, both and contain a B3-DNA binding domain that is shared by transcription factors that regulate plant embryogenesis. To study gene function, dsRNA against ( ) was applied to the roots of . Compared with those of the controls, the expression of was reduced by 43.3%, 22.1%, and 26.2% on the first, third, and fifth days after treatment, respectively. The -treated plants presented several morphological defects, mostly in the roots. Compared with water-treated plants, the -treated plants presented reduced developmental parameters, including root length, number of adventitious roots, root fresh and dry weights, plant height, and aboveground biomass. Additionally, safety assessment suggested that this treatment did not silence genes from non-target plants, including rice and tomato; nor did it inhibit root growth in those species. Collectively, these results suggest that plays an important role in root development in and provides a potential target for the development of species-specific RNAi-based herbicides.