Aspartic Acid Catalyzed by Asparaginase Provides Rice with Broad-Spectrum Resistance

Amino acid metabolism plays a key role in regulating interactions between plants and pathogens. Asparaginase hydrolyzes asparagine, a major nitrogen transport and storage amino acid, into aspartate. However, the immune function of plants asparaginase remains largely unknown. Rice possesses two asparaginase genes, OsASNase1 and OsASNase2, the function of which is unknown. In this study, we revealed that both OsASNase1 and OsASNase2 are cytoplasmic asparaginases that hydrolyze asparagine into aspartic acid and ammonia. Overexpression of OsASNase1 and OsASNase2 enhanced rice resistance to bacterial and fungal pathogens, while knocking them out compromised rice resistance. OsASNase1 - and OsASNase2 -mediated broad-spectrum disease resistance promote pathogen-associated molecular pattern-triggered immunity. Conserved autoproteolytic threonine residue is essential for their enzyme activity and immune function, and identified aspartic acid as a key molecule in plant immunity. This study reveals a novel mechanism linking asparagine metabolism to rice immunity and provides a target for breeding disease-resistant crops.