Loss of OsSPL8 Function Confers Improved Resistance to Glufosinate and Abiotic Stresses in Rice

ABSTRACT Weeds are among the most significant factors contributing to decreases in crop yield and quality. Glufosinate, a nonselective, broad‐spectrum herbicide, has been extensively utilized for weed control in recent decades. However, crops are usually sensitive to glufosinate. Therefore, the development of glufosinate‐resistant crops is crucial for effective weed management in agriculture. In this study, we characterized a SQUAMOSA promoter‐binding‐like (SPL) factor, OsSPL8, which acts as a negative regulator of glufosinate resistance by inhibiting the transcription of OsGS1;1 and OsGS2 and consequently reducing GS activity. Furthermore, the loss of OsSPL8 function enhanced tolerance to drought and salt stresses. Transcriptomic comparisons between the gar18‐3 mutant and wild type revealed that OsSPL8 largely downregulates stress‐responsive genes and upregulates growth‐related genes. We demonstrated that OsSPL8 directly regulates OsOMTN6 and OsNAC17, which influence drought tolerance. In addition, OsSPL8 directly represses the expression of salt stress tolerance‐related genes such as OsHKT1.1 and OsTPP1. Collectively, our results demonstrate that OsSPL8 is a negative regulator of both glufosinate resistance and abiotic stress tolerance. Summary statement This study revealed that OsSPL8 acts as a negative regulator of glufosinate resistance in rice by directly inhibiting the transcription of GLUTAMINE SYNTHETASE 1;1 (OsGS1;1) and GLUTAMINE SYNTHETASE 2 (OsGS2). Meanwhile, loss of OsSPL8 function enhances tolerance to drought and salinity stress.