The field of plant hormonomics focuses on the qualitative and quantitative analysis of the hormone complement in plant samples, akin to other omics sciences. Plant hormones, alongside primary and secondary metabolites, govern vital processes throughout a plant's lifecycle. While active hormones have received significant attention, studying all related compounds provides valuable insights into internal processes. Conventional single-class plant hormone analysis employs thorough sample purification, short analysis and triple quadrupole tandem mass spectrometry. Conversely, comprehensive hormonomics analysis necessitates minimal purification, robust and efficient separation and better-performing mass spectrometry instruments. This review summarizes the current status of plant hormone analysis methods, focusing on sample preparation, advances in chromatographic separation and mass spectrometric detection, including a discussion on internal standard selection and the potential of derivatization. Moreover, current approaches for assessing the spatiotemporal distribution are evaluated. The review touches on the legitimacy of the term plant hormonomics by exploring the current status of methods and outlining possible future trends.
- Keywords
- Hormonomics, Internal standard, Liquid chromatography, Mass spectrometry, Matrix effect, Metabolomics, Omics, Plant hormone, Solid phase extraction,
- Publication type
- Journal Article MeSH
- Review MeSH
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.
- Keywords
- mycorrhizal fungi, parasitic plants, plant hormones, rhizosphere, root exudates, small-molecule communication, strigolactones,
- MeSH
- Chromatography, Liquid MeSH
- Cytokinins metabolism MeSH
- Heterocyclic Compounds, 3-Ring metabolism MeSH
- Mass Spectrometry MeSH
- Fungi physiology MeSH
- Host-Pathogen Interactions MeSH
- Plant Roots metabolism microbiology MeSH
- Abscisic Acid metabolism MeSH
- Salicylic Acid metabolism MeSH
- Indoleacetic Acids metabolism MeSH
- Lactones metabolism MeSH
- Mycorrhizae physiology MeSH
- Orobanche growth & development microbiology MeSH
- Nicotiana growth & development microbiology MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Cytokinins MeSH
- GR24 strigolactone MeSH Browser
- Heterocyclic Compounds, 3-Ring MeSH
- indoleacetic acid MeSH Browser
- Abscisic Acid MeSH
- Salicylic Acid MeSH
- Indoleacetic Acids MeSH
- Lactones MeSH
Strigolactones are plant hormones regulating cytoskeleton-mediated developmental events in roots, such as lateral root formation and elongation of root hairs and hypocotyls. The latter process was addressed herein by the exogenous application of a synthetic strigolactone, GR24, and an inhibitor of strigolactone biosynthesis, TIS108, on hypocotyls of wild-type Arabidopsis and a strigolactone signaling mutant max2-1 (more axillary growth 2-1). Owing to the interdependence between light and strigolactone signaling, the present work was extended to seedlings grown under a standard light/dark regime, or under continuous darkness. Given the essential role of the cortical microtubules in cell elongation, their organization and dynamics were characterized under the conditions of altered strigolactone signaling using fluorescence microscopy methods with different spatiotemporal capacities, such as confocal laser scanning microscopy (CLSM) and structured illumination microscopy (SIM). It was found that GR24-dependent inhibition of hypocotyl elongation correlated with changes in cortical microtubule organization and dynamics, observed in living wild-type and max2-1 seedlings stably expressing genetically encoded fluorescent molecular markers for microtubules. Quantitative assessment of microscopic datasets revealed that chemical and/or genetic manipulation of strigolactone signaling affected microtubule remodeling, especially under light conditions. The application of GR24 in dark conditions partially alleviated cytoskeletal rearrangement, suggesting a new mechanistic connection between cytoskeletal behavior and the light-dependence of strigolactone signaling.
- Keywords
- Arabidopsis hypocotyl, GR24, TIS108, kymographs, light, max2-1 mutant, microtubule dynamics, microtubule organization,
- Publication type
- Journal Article MeSH
