Arabidopsis SSL1 encoding AtMWFE subunit of mitochondrial complex I regulates leaf development and reactive oxygen species

Mitochondrial complex I is an NADH-ubiquinone oxidoreductase responsible for 40% of the production of mitochondrial ATP. It contains 14 core subunits and 25–35 non-core ones in different organisms. However, the role of these subunits in plant development remains largely unknown. Here, we report a novel Arabidopsis T-DNA insertion mutant. The T-DNA insertion mutant produced smaller and more serrated leaves than wild-type control. So, it is named that the Arabidopsis small and serrated leaves 1 (ssl1). We identified a T-DNA insertion in the AtMWFE locus- that disrupted the function of AtMWFE in ssl1. AtMWFE encodes a conserved non-core subunit of mitochondrial complex I. The expression of AtMWFE complemented the leaf developmental defects of ssl1- thus SSL1 is the AtMWFE subunit of mitochondrial complex I. We also showed that the compromise of SSL1/AtMWFE function led to the accumulation of ROS. Our findings reveal that SSL1/AtMWFE is required for the function of mitochondrial complex I and the proper ROS level in leaves, and demonstrate that SSL1/AtMWFE plays a critical role in leaf development.