Most plants rely on the arbuscular mycorrhizal symbiosis to meet their P requirements. Interestingly, while several plant lineages have abandoned this symbiosis during their evolution, this loss is often associated to a symbiont switch, with the development of more recent associations, such as with ectomycorrhizae or orchid mycorrhizae. Surprisingly, no particular microbial adaptation has been described for non-mycorrhizal (NM) Brassicaceae, and suspected NM Cyperaceae, and Caryophyllaceae plants, raising the question of how they support their P nutrition. We hypothesize that diverse fungi may play analogous roles to arbuscular mycorrhizal fungi, contributing significantly to P nutrition of NM plants, particularly in P-deficient soils. By examining plant genomes for genes essential for the establishment of the AM symbiosis we show the absence of five of these crucial genes in Caryophyllaceae and Cyperaceae plants, mirroring observations for the known NM Brassicaceae family. Then, to characterize the root-associated microbiota of NM plants, we conducted a large-scale ITS2 metabarcoding analysis on wild-growing NM species across 7 sites of contrasting levels of plant-available P. NM plants select a slightly different root microbiota compared with their mycorrhizal neighbours, albeit with little similarities between the NM families. This supports the hypothesis that Brassicaceae, Cyperaceae, and Caryophyllaceae might have developed divergent fungus-mediated adaptations. By employing machine learning, we identified fungal taxa associated with higher P accumulation in NM plants, primarily from the Helotiales (24 OTUs) and Pleosporales (19 OTUs) orders, including known plant-beneficial lineages. To test their impact on NM plants, we isolated representative strains of these taxa and examined their effects on growth and P content of NM plant species. These results led us to focus on isolates from two Helotiales lineages (including Titaea maxilliformis), with current experiments aiming to assess if these fungi can (1) enhance the growth and P acquisition of several native NM plant species in P-limiting conditions, and (2) transfer P to these plant species. These findings should establish the interactions with such “mycorrhiza-like” fungi as new adaptations, balancing the loss of the arbuscular mycorrhizal symbiosis in NM plants.