A Mass Spectrometry-Based Study Shows that Volatiles Emitted by Arthrobacter agilis UMCV2 Increase the Content of Brassinosteroids in Medicago truncatula in Response to Iron Deficiency Stress

• Published in: Molecules (Basel, Switzerland) Switzerland), 2019-08, Vol.24 (16), p.3011
• Main Authors: Flores-Cortez, Idolina, Winkler, Robert, Ramírez-Ordorica, Arturo, Elizarraraz-Anaya, Ma Isabel Cristina, Carrillo-Rayas, María Teresa, Valencia-Cantero, Eduardo, Macías-Rodríguez, Lourdes
• Format: Article
• Language: English
• Subjects: Abiotic factors; Agricultural Inoculants; Alfalfa; Allelochemicals; Arthrobacter; Arthrobacter - metabolism; Brassinolide; Brassinosteroids; Brassinosteroids - analysis; Brassinosteroids - metabolism; Chromatography; Cluster Analysis; Crop yield; DLI-ESI-MS; Fe deficiency; Flavonoids; Gas chromatography; Growth conditions; Homeostasis; Iron; Iron - metabolism; legumes; Mass spectrometry; Mass spectroscopy; Medicago truncatula; Medicago truncatula - drug effects; Medicago truncatula - growth & development; Medicago truncatula - metabolism; Metabolism; Metabolites; microbial volatiles; Microorganisms; Models, Biological; Nutrient deficiency; Pigments; Plant stress; Principal components analysis; Redox reactions; Scientific imaging; Seedlings - drug effects; Seedlings - growth & development; Seedlings - metabolism; Spectrometry, Mass, Electrospray Ionization - methods; Spectroscopy; Stress, Physiological; Volatile compounds; Volatile Organic Compounds - pharmacology; Volatiles
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules24163011

Iron is an essential plant micronutrient. It is a component of numerous proteins and participates in cell redox reactions; iron deficiency results in a reduction in nutritional quality and crop yields. Volatiles from the rhizobacterium UMCV2 induce iron acquisition mechanisms in plants. However, it is not known whether microbial volatiles modulate other metabolic plant stress responses to reduce the negative effect of iron deficiency. Mass spectrometry has great potential to analyze metabolite alterations in plants exposed to biotic and abiotic factors. Direct liquid introduction-electrospray-mass spectrometry was used to study the metabolite profile in due to iron deficiency, and in response to microbial volatiles. The putatively identified compounds belonged to different classes, including pigments, terpenes, flavonoids, and brassinosteroids, which have been associated with defense responses against abiotic stress. Notably, the levels of these compounds increased in the presence of the rhizobacterium. In particular, the analysis of brassinolide by gas chromatography in tandem with mass spectrometry showed that the phytohormone increased ten times in plants grown under iron-deficient growth conditions and exposed to microbial volatiles. In this mass spectrometry-based study, we provide new evidence on the role of UMCV2 in the modulation of certain compounds involved in stress tolerance in .