Research Projects

Rice constitutes the most significant staple food crop for over half of the global human population. However, its cultivation is critically jeopardized by blast disease, which is instigated by the phytopathogenic fungus Magnaporthe oryzae and is widely regarded as the most destructive fungal disease impacting rice cultivation on a global scale. It can invade any part of the rice plant, leading to yield losses ranging from 5% to 50%, with the possibility of total crop failure under optimal conditions. Consequently, the development of effective strategies to mitigate damage and prevent crop loss is imperative. Matrix metalloproteinases (MMPs) are metal-dependent endopeptidases that function as extracellular matrix-degrading enzymes in animal systems. Interestingly, MMP activity has also been observed in various plants, yet their specific roles are still not well understood. A previous report identified and characterized OsMMP1 in rice, which plays a crucial role in maintaining cell wall integrity. When OsMMP1 is overexpressed in tobacco plants, it can reduce the permeability of plasmodesmata by increasing callose deposition. This change restricts the size exclusion limit of plasmodesmata and their trafficking system. Meanwhile, the fungal pathogen M. oryzae uses invasive hyphae to penetrate host cells and takes advantage of plasmodesmata for its movement within cells. Thus, it can be proposed that MMP1 might act as a crucial factor in restricting blast invasion as well as the cell-to-cell movement of M. oryzae. This hypothesis is backed by prior experiments, which demonstrated that treatment with exogenous MMPs (collagenase and gelatinase B) led to a reduction in M. oryzae spore penetration and infection on glass surfaces. Despite the existing in vitro research, comprehensive studies investigating the in vivo roles of MMPs in regulating extracellular matrix dynamics during M. oryzae infection are conspicuously absent. How MMPs exert their effects and which proteins they interact with to limit the pathogen's entry or migration remain completely unknown. Additionally, the specific substrates that MMP1 binds to to perform its biological functions need to be identified. Hence, an in-depth exploration of the in vivo roles of MMP1 in rice is crucial, as it may reveal new strategies to combat this fungal threat and ensure the security of rice production and food resources.