The presence of Lens culinaris at different nodulation stages alters the expression of the genes TdNAR2.2, TdNRT1.1, TdAMT1.1, and TdAMT1.2 in an intercropping system with Triticum durum

Background and Aims Nitrogen (N) is an essential macronutrient for plant growth and key physiological processes. Consequently, the application of nitrogen fertilizers in agriculture is a widespread practice aimed at meeting crop nutritional demands. Excessive use of these fertilizers lead to environmental degradation. An alternative approach involves biological nitrogen fixation (BNF), which is carried out by legumes through symbiosis with rhizobia. Legume/cereal intercropping systems provide an opportunity to exploit this beneficial trait of legumes. Methods In the present study, we evaluated the effect of Lens culinaris at different stages of nodulation: non-nodulated (2 days), early nodulation (15 days), and late nodulation (30 days) on the growth and gene expression of Triticum durum in an intercropping system. Specifically, the expression of nitrate (NO₃⁻) transporter genes and ammonium (NH₄⁺) transporter genes. The intercropping system simulated alternating rows of both species, with or without KNO₃ application to mimic nitrogen fertilization. Results The presence of lentil at the late nodulation stage improved wheat growth when intercropping was combined with KNO₃, while lentil growth was not markedly affected. Furthermore, wheat presence and nitrogen deficiency synergestically stimulated nodule formation in lentil at both early and late stages of interaction. Finally, the presence of non-nodulated lentil induced the expression of TdNAR2.2 , TdNRT1.1 , TdAMT1.1 , and TdAMT1.2 in intercropped wheat under fertilized conditions. Conclusion Our results suggest that T. durum growth benefits from intercropping with L. culinaris , due to enhanced nodulation in the legume and the upregulation of NO₃⁻ and NH₄⁺ uptake genes.