Microbial enhancement of crop resource use efficiency

Naturally occurring soil microbes may be used as inoculants to maintain crop yields despite decreased resource (water and nutrient) inputs. Plant symbiotic relationships with mycorrhizal fungi alter root aquaporin gene expression and greatly increase the surface area over which plant root systems take up water and nutrients. Soil bacteria on the root surface alter root phytohormone status thereby increasing growth, and can make nutrients more available to the plant. Combining different classes of soil organism within one inoculant can potentially take advantage of multiple plant growth-promoting mechanisms, but biological interactions between inoculant constituents and the plant are difficult to predict. Whether the yield benefits of such inocula allow modified nutrient and water management continues to challenge crop biotechnologists.

Graphical abstract. Physiological mechanisms by which mycorrhizal and rhizobacterial inoculants affect crop resource efficiency. Red arrows indicate mass fluxes of compounds to and from the roots, while blue arrows indicate interdependencies of processes.Figure optionsDownload full-size imageDownload high-quality image (221 K)Download as PowerPoint slideHighlights► Mycorrhizal symbioses alter crop water relations by modulating aquaporin expression. ► Rhizobacteria alter root growth and long-distance signals by modulating phytohormones. ► Rhizobacterial and mycorrhizal inoculants allow decreased fertiliser applications.