Abstract
Belowground interactions of plants with other organisms in the rhizosphere rely on extensive small-molecule communication. Chemical signals released from host plant roots ensure the development of beneficial arbuscular mycorrhizal (AM) fungi which in turn modulate host plant growth and stress tolerance. However, parasitic plants have adopted the capacity to sense the same signaling molecules and to trigger their own seed germination in the immediate vicinity of host roots. The contribution of AM fungi and parasitic plants to the regulation of phytohormone levels in host plant roots and root exudates remains largely obscure. Here, we studied the hormonome in the model system comprising tobacco as a host plant, Phelipanche spp. as a holoparasitic plant, and the AM fungus Rhizophagus irregularis. Co-cultivation of tobacco with broomrape and AM fungi alone or in combination led to characteristic changes in the levels of endogenous and exuded abscisic acid, indole-3-acetic acid, cytokinins, salicylic acid, and orobanchol-type strigolactones. The hormonal content in exudates of broomrape-infested mycorrhizal roots resembled that in exudates of infested non-mycorrhizal roots and differed from that observed in exudates of non-infested mycorrhizal roots. Moreover, we observed a significant reduction in AM colonization of infested tobacco plants, pointing to a dominant role of the holoparasite within the tripartite system.
Highlights
Rhizosphere is a dynamic platform for complex interactions of plants with the other biotic and abiotic components of the soil ecosystem
Since most of the land plants are involved in symbiotic interactions with arbuscular mycorrhizal (AM) fungi [8], the chemical communication within pathosystems of plant hosts and holoparasites in nature is performed in the context of AM development
Host plants regulate the extent of mycorrhization to maintain the balance between beneficial AM symbiosis and AM parasitism [55]
Summary
Rhizosphere is a dynamic platform for complex interactions of plants with the other biotic and abiotic components of the soil ecosystem. The chemical composition of root exudates largely shapes the plant-associated microbial communities [1]. The selective enrichment of bacterial species in the rhizosphere is based on their specific substrate preferences secured by the plant species [2]. The exuded chemical components have been shown to be functionally implicated in diverse biological processes such as symbiosis, pathogenesis, allelopathy, and mineral nutrition [3,4]. All other biotic factors jointly contribute to the chemical composition in the rhizosphere, and their metabolic activities are subjected to feedback regulation. The rhizosphere microbiome modulates root metabolism and exudation by driving long-distance signaling and systemic transcriptional reprogramming in plants [5]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
