Overexpression of Alfalfa SIMK Promotes Root Hair Growth, Nodule Clustering, and Shoot Biomass Production

The study demonstrated that manipulating the expression of stress-induced MAPK (SIMK) in alfalfa plants significantly impacted root hair growth, nodule formation, and shoot biomass production. Downregulation of SIMKK and SIMK through RNA interference resulted in reduced root hair growth, fewer infection threads, and nodules, as well as decreased shoot biomass. Conversely, overexpression of GFP-tagged SIMK promoted root hair growth, increased infection thread and nodule clustering, and enhanced shoot biomass. These findings highlighted the potential biotechnological applications of SIMK in improving alfalfa growth and nitrogen fixation.