Bioinoculants as a means of increasing crop tolerance to drought and phosphorus deficiency in legume-cereal intercropping systems

Abstract

Ensuring plant resilience to drought and phosphorus (P) stresses is crucial to support global food security. The phytobiome, shaped by selective pressures, harbors stress-adapted microorganisms that confer host benefits like enhanced growth and stress tolerance. Intercropping systems also offer benefits through facilitative interactions, improving plant growth in water- and P-deficient soils. Application of microbial consortia can boost the benefits of intercropping, although questions remain about the establishment, persistence, and legacy effects within resident soil microbiomes. Understanding microbe- and plant-microbe dynamics in drought-prone soils is key. This review highlights the beneficial effects of rhizobacterial consortia-based inoculants in legume-cereal intercropping systems, discusses challenges, proposes a roadmap for development of P-solubilizing drought-adapted consortia, and identifies research gaps in crop-microbe interactions.

Roles of rhizobacteria in cereals

“…Some of the major abiotic stresses on cereals are salinity, drought, low and high temperatures, and nutrient deficiencies [22,26]. High saline content in the soil leads to osmotic stress, nutrient deficiency, ion toxicity, hormonal imbalance, and oxidative stress in plants.…”

“…Beneficial traits such as nitrogen fixation, phosphorous solubilization, IAA biosynthesis, naringenin biosynthesis, biocontrol, and rhizoremediation, have become successful in the transfer and optimization within some rhizobacteria [32]. However, PGPR colonization and performance under real field conditions have not always been consistent [26]. As discussed in previous sections, the rhizobacterial population is highly dependent on environmental factors, host factors as well as cultural practices.…”

“…Further, not all rhizosphere bacteria can successfully be cultured in synthetic media. For effective results, the PGPR should be able to survive in foreign soils while competing with the established microbial community [26]. Moreover, host specificity plays a role in successful rhizobacterial colonization.…”

“…As a result, the microbial density in the rhizosphere increases up to 10 to 100 times than the bulk soil. The rhizosphere is therefore called the second genome [1,26] or an extended genome [20] of plants. The majority of the rhizosphere community is bacteria, with approx.…”

Identifying functional multi-host shuttle plasmids to advance synthetic biology applications inMesorhizobiumandBradyrhizobium

“…Identification of basic genetic tools will enable plasmid-based engineering strategies that facilitate more advanced synthetic biology techniques (Nora et al, 2019). Aside from the development of novel organelles, these organisms could also be manipulated for other applications, including the development of elite bioinoculants or expanding symbiosis to non-legumes (Checcucci et al, 2017;Pankievicz et al, 2019;Krönauer and Radutoiu, 2021;Benmrid et al, 2023). free-living growth.…”