Nodule Senescence Regulation by GmPRLP in Response to Rhizobial Type III Effectors NopL and NopP in Soybean

Abstract Symbiotic nitrogen fixation efficiency in soybean can be compromised by nodule senescence; however, the mechanisms by which rhizobial type III effectors NopL and NopP─which disrupt plant immune signaling pathways and promote symbiotic compatibility─regulate nodule senescence in soybean remain unclear. Therefore, we investigated this aspect and identified GmPRLP as a key host gene responsive to NopL and NopP, via quantitative trait locus mapping and whole-genome resequencing. Functional analysis using hairy root transformation showed that GmPRLP overexpression accelerated nodule senescence, as evidenced by increased bacteroid degradation and membrane lipid peroxidation, whereas GmPRLP silencing delayed senescence. Transcriptomic profiling and weighted gene coexpression network analysis indicated that GmPRLP promotes nodule senescence by activating ethylene signaling genes, including GmACS7, GmACO, and GmERFs. To conclude, GmPRLP mediates soybean responses to rhizobial effectors and regulates nodule senescence through the ethylene signaling pathway, providing a potential target for improving nitrogen fixation efficiency in soybean breeding.