Crying out for help with root exudates: adaptive mechanisms by which stressed plants assemble health-promoting soil microbiomes

• Published in: Current opinion in microbiology Vol. 49; pp. 73 - 82
• Main Authors: Rolfe, Stephen A, Griffiths, Joseph, Ton, Jurriaan
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.06.2019
• Subjects: biotic stress; chemistry; exudation; health promotion; immune response; microbial activity; microbiome; Microbiota; Plant Diseases - immunology; Plant Diseases - microbiology; Plant Exudates - chemistry; Plant Physiological Phenomena; plant protection; plant response; Plant Roots - chemistry; Plant Roots - immunology; Plant Roots - microbiology; Plants - chemistry; Plants - immunology; Plants - microbiology; Rhizosphere; root exudates; Secondary Metabolism; soil; Soil Microbiology; Stress, Physiological; wheat
• ISSN: 1369-5274; 1879-0364; 1879-0364
• DOI: 10.1016/j.mib.2019.10.003

•The cry-for-help model states that stressed plants assemble protective rhizobiomes.•Plants attacked by pathogens or herbivores change their root exudation chemistry.•Specific rhizosphere signals alter the composition and activity of the rhizobiome.•The modified rhizobiome protects plants via direct and indirect mechanisms.•Legacy effects on the soil microbiome can benefit the next generation of plants. Plants employ immunological and ecological strategies to resist biotic stress. Recent evidence suggests that plants adapt to biotic stress by changing their root exudation chemistry to assemble health-promoting microbiomes. This so-called ‘cry-for-help’ hypothesis provides a mechanistic explanation for previously characterized soil feedback responses to plant disease, such as the development of disease-suppressing soils upon successive cultivations of take all-infected wheat. Here, we divide the hypothesis into individual stages and evaluate the evidence for each component. We review how plant immune responses modify root exudation chemistry, as well as what impact this has on microbial activities, and the subsequent plant responses to these activities. Finally, we review the ecological relevance of the interaction, along with its translational potential for future crop protection strategies.