Impact of intercropping on grain ionome and Pseudomonas spp. and Enterobacterales abundances
Cereal-legume intercropping (IC) has been proposed to meet the challenges of increasing yields and improving crop nutrient quality; crucial for both food security and human health. Legumes are of particular interest, as they can fix atmospheric nitrogen and therefore reduce the need for N-fertilizers. This study aimed to characterize the impact of pea-wheat intercropping on grain ionome composition, and asses a possible relation with the abundance of Pseudomonas spp. and Enterobacterales in plant roots, two groups involved in Fe, Mg and P mobilization. In a field experiment, four pea (Pisum sativum) varieties were cultivated in sole- or intercropping with wheat (Triticum aestivum) in two different soil types. Grain ionome was characterised by mass spectrometry. Pseudomonas spp. and Enterobacterales abundances were determined by qPCR.  A positive correlation was found between increased abundance of Pseudomonas spp. and higher Mo content in IC peas. Enterobacterales increased in intercropped wheat and that was positively correlated with Mn, Fe, and Cu grain content. Mg, Ca, Ni and Mn were also increased in intercropped peas, while Cu, Fe, S, Zn, N, C and Mn were increased in intercropped wheat.  These findings show that intercropping may favour the concentration of specific ions in pea and wheat grains. This enhancement was related to an increase abundance of Pseudomonas spp. in IC. Further research is necessary to understand the underlying mechanisms behind element accumulation in IC grains and to explore the potential benefits of intercropping on plant nutrition and growth.