A Large-Scale Hydroponic Evaluation of Rice Mutants for Pythium Resistance

Rice is a major staple crop worldwide. However, the occurrence of rice diseases during cultivation poses a significant challenge to achieving optimal yields. Among the major pathogens, Pythium species, which cause seedling blight, are of particular concern. Pythium infects rice roots through zoospores, mycelia, or oospores, leading to root rot, stunting, yellowing, and ultimately seedling damping-off. While many disease resistance-related genes have been reported in rice, only very limited research has been associated with resistance to Pythium infection. In this study, we aimed to establish a rapid screening system to identify rice lines that are resistant or susceptible to the Pythium pathogen in rice nurseries. We conducted evaluations on important factors, including virulence, inoculation method, seed-soaking period, and the measurement of disease severity. As a result, we successfully developed a screening system that allows for high-throughput and rapid screening of the Taiwan Rice Insertional Mutant (TRIM) library for mutant lines exhibiting resistance to P. arrhenomanes. Furthermore, we identified a slightly resistant TRIM line and explored potential genes encoding endoglucanase-1 precursor and malonyl-CoA decarboxylase that may be involved in conferring resistance to P. arrhenomanes.