Positively regulating role of the key evening complex gene AhLUX1 in peanut nodulation

Biological nitrogen fixation via nodulation in legumes is highly energy intensive. In legumes, light signals not only regulate photosynthesis, morphogenesis, and growth, but also play key roles in controlling nodulation and nitrogen fixation during interactions with rhizobia. LUX (lux arrhythmo) is a core component of the evening complex (EC), which ensures accurate temporal output of multiple signals under light-dark cycles. Unlike soybean and many other legumes, peanut primarily uses a crack-entry mode of rhizobial invasion, and the role of AhLUX1 in peanut nodulation has remained unclear. Here, this study shows that AhLUX1 is strongly induced by rhizobial infection and is predominantly expressed in root tips, lateral root primordia, developing nodules, and mature nodules. Subcellular localization analysis indicates that AhLUX1 is localized in the nucleus. Functional analyses show that overexpression of AhLUX1 (OE-AhLUX1) significantly increases nodule number, whereas silencing (RNAi-AhLUX1) or knockout (CR-AhLUX1) markedly reduces nodulation, demonstrating that AhLUX1 is a positive regulator of nodulation in peanut. To clarify the underlying mechanism, the expression of nodulation marker genes in AhLUX1-overexpressing and AhLUX1-silenced roots. The results suggest that AhLUX1 modulates peanut nodulation by regulating the expression of key nodulation genes. Together, these findings link a light-signaling component to belowground nodulation and nitrogen fixation and provide a genetic resource for breeding high-efficiency peanut varieties through manipulation of the light-signaling pathway.