Metabolomics reveal drought-stress responses in guayule, a semi-arid rubber crop

Authors: Phan, Huy; Abdel-Haleem, Hussein

Submitted to: Metabolomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2026
Publication Date: 6/16/2026
Citation: Phan, H.M., Abdel-Haleem, H.A. 2026. Metabolomics reveal drought-stress responses in guayule, a semi-arid rubber crop. Metabolomics. 22. Article 97. https://doi.org/10.1007/s11306-026-02487-5.
DOI: https://doi.org/10.1007/s11306-026-02487-5

Interpretive Summary: This study had two primary goals: 1) to characterize drought-induced metabolomic profiles of guayule focusing on MVA and MEP pathway metabolites linked to resin and rubber biosynthesis; and 2) to determine whether distinct metabolomic signatures correlate with different genetic backgrounds. Drought-induced metabolomic changes reveal contrasting cultivar strategies and identify pathway markers linked to increased rubber biosynthesis in guayule. Overall, this work advances the understanding of guayule's metabolic reprogramming under drought stress. It highlights how MVA and MEP pathways coordinate increased rubber biosynthesis. These insights provide valuable targets for molecular breeding and biotechnological innovation. Ultimately, they support developing guayule cultivars capable of maintaining productivity in water-limited climates.

Technical Abstract: Objectives and Methods: Using untargeted metabolomic approach, this study analyzed drought-induced metabolomic changes in two guayule cultivars, AZ-4 and CAL-2, focusing on key metabolites linked to resin and rubber biosynthesis. Results: We identified 53 drought-responsive metabolites, with 27 differing significantly between cultivars. AZ 4 showed increased stress signaling molecules and precursor metabolites, indicating rapid metabolic activation under drought, while CAL 2 accumulated triterpenoid saponins and lysophospholipids, suggesting membrane stabilization and long term osmo protective defense. Under drought, both cultivars shared depletion of 4'-phosphopantothenoylcysteine, indicating a potential bottleneck in Coenzyme A biosynthesis. Reduced ubiquinone-1 further suggested a diversion of isoprenoid precursors away from respiration and toward secondary metabolism. This shift is linked to activation of the MVA and MEP pathways, which enhanced flux into rubber and resin biosynthesis rather than ubiquinone production. Although cis-1,4-polyisoprene was not directly measured, the observed increases in key terpenoid precursors and pathway-associated metabolites are consistent with enhanced flux toward rubber biosynthesis under drought conditions. Conclusion: Divergent metabolic patterns reflect genetic and biochemical diversity: AZ 4 favors rapid stress signaling and precursor synthesis, whereas CAL 2 emphasizes antioxidant and osmoprotective mechanisms. These biomarkers make them valuable for breeding drought-tolerant, and high-yield guayule germplasm to advance sustainable rubber production in dry regions.