Elucidating Drought-Tolerance Mechanisms in Plant Roots through 1H NMR Metabolomics in Parallel with MALDI-MS, and NanoSIMS Imaging Techniques

• Published in: Environmental science & technology Vol. 56; no. 3; pp. 2021 - 2032
• Main Authors: Honeker, Linnea K, Hildebrand, Gina A, Fudyma, Jane D, Daber, L Erik, Hoyt, David, Flowers, Sarah E, Gil-Loaiza, Juliana, Kübert, Angelika, Bamberger, Ines, Anderton, Christopher R, Cliff, John, Leichty, Sarah, AminiTabrizi, Roya, Kreuzwieser, Jürgen, Shi, Lingling, Bai, Xuejuan, Velickovic, Dusan, Dippold, Michaela A, Ladd, S Nemiah, Werner, Christiane, Meredith, Laura K, Tfaily, Malak M
• Format: Journal Article
• Language: English
• Published: Easton American Chemical Society 01.02.2022
• Subjects: Antioxidants; Carbohydrates; Drought resistance; Environmental stress; Fatty acids; Imaging techniques; Legumes; Metabolic pathways; Metabolic response; Metabolism; Metabolomics; Microorganisms; NMR; Nuclear magnetic resonance; Organic matter; Plant roots; Pyruvic acid; Rainforests; Rhizosphere; Roots; Spatial distribution; Species
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/acs.est.1c06772

As direct mediators between plants and soil, roots play an important role in metabolic responses to environmental stresses such as drought, yet these responses are vastly uncharacterized on a plant-specific level, especially for co-occurring species. Here, we aim to examine the effects of drought on root metabolic profiles and carbon allocation pathways of three tropical rainforest species by combining cutting-edge metabolomic and imaging technologies in an in situ position-specific 13C-pyruvate root-labeling experiment. Further, washed (rhizosphere-depleted) and unwashed roots were examined to test the impact of microbial presence on root metabolic pathways. Drought had a species-specific impact on the metabolic profiles and spatial distribution in Piper sp. and Hibiscus rosa sinensis roots, signifying different defense mechanisms; Piper sp. enhanced root structural defense via recalcitrant compounds including lignin, while H. rosa sinensis enhanced biochemical defense via secretion of antioxidants and fatty acids. In contrast, Clitoria fairchildiana, a legume tree, was not influenced as much by drought but rather by rhizosphere presence where carbohydrate storage was enhanced, indicating a close association with symbiotic microbes. This study demonstrates how multiple techniques can be combined to identify how plants cope with drought through different drought-tolerance strategies and the consequences of such changes on below-ground organic matter composition.