Drought stress drives strong effects on the soil P content (−9.18%). It was reported that drought treatments that included drying–rewetting cycles had no effect on P uptake by plants, while long-term drought stress reduced the P content (He and Dijkstra, 2014). The drought-induced P changes can be explained by the soil pH. Reducing soil pH leads to the solubilization of P into calcium phosphate under drought conditions (Zhang et al., 2020). In light of growing concerns about water and nutrient deficiency in terrestrial ecosystems, especially those used for agriculture, the number of studies has increased on the impacts of drought stress on the structure and function of the root concerning the improved plant tolerance (He and Dijkstra, 2014; Naylor and Coleman-Derr, 2018). The root microbiome under drought stress drives variations in root phenotypic traits and exudates (He and Dijkstra, 2014).

Plants have evolved morphological and physiological strategies for P acquisition such as N fixation in legumes under low-P conditions (Lazali and Drevon, 2021). When water is available to the plant; desert wild plant species Glycyrrhiza uralensis can reduce N-to-P ratio in soil by increasing N and P absorption. N inputs to the soil enhance N- to-P ratio, reduce N resorption, and increase P resorption by G. uralensis. On the other hand, P inputs to the soil reduce N-to-P ratio but increase root biomass (Huang et al., 2018; Srivastava et al., 2022). Dai et al. (2020) revealed that long-term P inputs to the soil enhance microbe-mediated P mobilization, but long-term N inputs reduce the efficiency of P-solubilization by reducing soil pH.

Nutrient availability in the rhizosphere affects plant growth depending on the soil properties and plant features (Capek et al., 2018). Some reports confirm the role of root exudates in plant–microbe interactions under P deficiency (Carvalhais et al., 2013; Liu et al., 2022). The highest rhizosphere nutrient accumulation observed in poor soil conditions confirms the negative correlation between soil chemical parameters and available P. The main nutrients needed for plants are more available in the rhizosphere compared to bulk soil (Liu et al., 2022).

Plants rely on their interactions with microorganisms to scavenge the accessible P in the soil. The different microorganisms apply numerous strategies to obtain P from dryland soils for plant stabilization (Crain et al., 2018). Most terrestrial plants (except for Brassicaceae) are colonized with Arbuscular mycorrhiza fungi (AMF) and depend on the association between them, resulting in P uptake from soil (Soudzilovskaia et al., 2015). The efficacy of AMF in root colonization depends on the interactions between the root and rhizosphere microbiome (Reichert et al., 2022). The percentage of AMF colonization is nutrient-dependent, which is improved in low-P conditions but reduced in high P conditions possibly due to energy costs (Chen et al., 2020). The roots that efficiently acquire P were poorly protected against soil-borne fungal pathogens such as Phytophthora. By contrast, species with thicker, denser, and less branched fine roots that strongly depend on AMF for P acquisition are supposedly less susceptible to pathogens (Laliberte et al., 2015). Edlinger et al. (2022) reported that AMFs in grassland soils were much more effective in P uptake than in cropland soils, which were reduced by fungicide inputs. Thus, reducing the use of fungicides could lead to AMF enrichment and a better P uptake in agroecosystems (Edlinger et al., 2022).

Almario et al. (2017) evaluated the plant–fungi interactions in a non-mycorrhizal association under P-poor conditions that confirmed the role of root fungal populations in P acquisition. Comparative analysis of root and rhizospheric fungal communities of Arabis alpina under normal and P-poor conditions was conducted using amplicon sequencing. A taxon belonging to Helotiales was established with higher relative abundance in the roots of A. alpina, which was correlated with a higher P uptake and plant growth promotion. This fungus displayed mycorrhiza-like performances (AMF-like fungi), comprising the colonization of the root, endophytic lifestyle, and P transfer to the plant (Almario et al., 2017).

In addition, P-solubilizing fungi can increase plant growth by promoting nutrient cycling, the synthesis of plant hormones, enzymes, and volatile organic compounds (Vassileva et al., 2022).

P-solubilizing bacteria (PSB) can improve P acquisition efficiency of roots through P mineralization in available forms. PSBs from the rhizospheres of different plant species showed different solubilization efficiency, which highlighted that host plants can play roles in engineering their associated microbiome to improve P acquisition (Amy et al., 2022; Angulo et al., 2022). There is a growing interest in applying PSBs (Abbasi et al., 2019; Abbasi et al., 2020a; Abbasi et al., 2021a; Abbasi et al., 2021b) because of their advantages such as eco-friendliness, low production cost, and high efficiency (Timofeeva et al., 2022), especially for acidic soils where Fe ions can fix P (Cui et al., 2022). Cui et al. (2022) demonstrated that Fe–P mobilization by an endophytic Streptomyces sp. CoT10 strain in Camellia oleifera was positively correlated with siderophore production. Applying Streptomyces CoT10 strain in C. oleifera was shown to facilitate P and Fe absorption, improve P content in the soil, and promote plant growth. Moreover, inoculation of Streptomyces CoT10 strain enriched some dominant groups of Actinobacteria, Proteobacteria, and Firmicutes in the rhizosphere and balanced the microbial P- and Fe-related functions. Thus, siderophore-producing strains can increase beneficial microbial interactions for P mobilization in Fe-rich soils, which can have benefits for sustainable agriculture. Abbasi et al. (2020b) reported that co-inoculation of P-solubilizing and siderophore-producing Streptomyces strains not only promotes a higher plant growth but also induces resistance against a fungus-like pathogen P. capsici by regulating ethylene-dependent genes. In addition, Liu et al. (2023) reported that herbivores grazing in grasslands can enhance soil-accessible P content and alkaline phosphatase activity in the rhizosphere by enriching the abundance of some PSBs. Several drought-tolerant PSBs were recommended to combat P deficiency ( Table 1 ). The application of these strains via innovative formulations could represent a promising approach to stress management in sustainable agriculture (Elhaissoufi et al., 2022).

Srivastava et al. (2022) investigated the genetic and functional diversity of polyphosphate-accumulating bacteria (PAB) in the rhizosphere soil of A. thaliana and depicted the contributions of Pseudomonas sp. in the P cycling. Interaction of PAB with A. thaliana can increase in response to salinity stress to promote plant growth through P solubilization, auxin, and siderophore production. In this case, the occurrence of Pseudomonas strains was recognized as a P accumulator in the soil. The authors showed that functional genes, i.e., polyphosphate kinase and exopolyphosphatase, have important roles in polyphosphate metabolism and bacterial growth (Srivastava et al., 2022). The positive interactions between Pseudomonas strains, P cycling, and plant growth show a potential of P. sp. to be used as plant growth-promoting bioproducts under P deficiency.

Macroorganisms such as earthworms or some free-living nematodes could modulate changes in the microbial interactions (Wang et al., 2022a), which may affect nutrient cycling and P uptake. Wan and Wong (2004) reported that earthworms Eisenia fetida and Pheretima guillelmi can accelerate the availability of P. Additionally, Zheng et al. (2022) showed that some predatory nematodes such as bacterial-feeding Eucephalobus induce changes in the abundance of specific bacterial communities, such as alkaline phosphomonoesterase (ALP)-producing bacteria, and improve P uptake (Zheng et al., 2022; Wang et al., 2022b). These studies provide novel insights into microbial-mediated mechanisms stimulated by other soil organisms that can influence P cycling in soil and improve P uptake by the plant.

The plant–microbe associations are reasonably important in eco-friendly bioremediation by breakdown, adsorption, and volatilization of toxic compounds. These processes can transform toxic material into nontoxic or inactive compounds (dos Santos et al., 2021). The high levels of arsenic (As) in the soil and plant can cause health risks to humans due to its carcinogenicity. At the root surfaces, P significantly reduces As uptake and affects As biotransformation by competing for As transporters (Wu et al., 2022a). Indeed, concentrations can be reduced in plants via the manipulation of soil P content (Anawar et al., 2018; Wu et al., 2022b).

There are multiple examples of the importance of P in plant tolerance to abiotic and biotic stresses (Tariq et al., 2019; Mahreen et al., 2023). Mahreen et al. (2023) evaluated the effects of a consortium of drought-tolerant PSB strains from the rice rhizosphere (Bacillus subtilis, B. cereus, and Brucella haematophilum) on three rice genotypes. These strains significantly improved seedling growth and drought tolerance as compared to non-inoculated plants under drought-stress conditions. These responses were positively correlated with the accumulation of proline, relative water content, membrane stability, and production of antioxidants. RNA-seq analysis indicated that most of the transcriptional shifts were related to genes explained to the functional categories involved in P transport, organic acid secretion, hormone metabolism, and TF regulation. P can also play a role in plant defense against pathogens. For instance, Val-Torregrosa et al. (2022) showed that the increase of P content in A. thaliana can lead to an elevated resistance against fungal pathogens such as Plectosphaerella cucumerina and Colletotrichum higginsianum. The authors reported that overexpression of plant miRNAs such as MIR399, loss of function of PHOSPHATE2 (PHO2), and plant treatments with phosphates were responsible for an elevated P content and a subsequent plant resistance to these pathogens. However, this seems to be dependent on the plant and pathogen designation, as well as on the P content. For instance, another study showed that an excess of P in rice plants could lead to an increased plant susceptibility to the blast fungus Magnaporthe oryzae (Campos-Soriano et al., 2020).