Metabolite analysis indicates role of flavones and free fatty acids in water deficit stress response of Cenchrus spinifex

Authors: CAO, JING - Beijing University Of Agriculture; LI, ZHENSONG - Qingdao Agricultural University; Monaco, Thomas; RONG, YUPING - Beijing University Of Agriculture

Submitted to: FLORA
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/10/2025
Publication Date: 4/21/2025
Citation: Cao, J., Li, Z., Monaco, T.A., Rong, Y. 2025. Metabolite analysis indicates role of flavones and free fatty acids in water deficit stress response of Cenchrus spinifex. FLORA. https://doi.org/10.1016/j.flora.2025.152729.
DOI: https://doi.org/10.1016/j.flora.2025.152729

Interpretive Summary: The impacts of drought on agriculture and grassland ecosystems are increasing, resulting in unexpected changes in plant communities due to the spread of invasive weed species. In this study, we evaluated how drought impacts seedling growth of the invasive annual grass coastal sandbur that is spreading rapidly around the globe. In particular, we evaluated how seedlings arising from heteromorphic (different sized) seeds react to three drought levels. The impacts of drought varied by seed type and our results offer new insights into how sandbur may be spreading into new drier environments. In addition, we showed that seed types varied in metabolite production under drought.

Technical Abstract: Because drought impacts agriculture worldwide and is a major driver of ecosystem dynamics, understanding drought response mechanisms in plants to intensified climate change is an essential aspect of forecasting ecosystem vulnerabilities. Here, we employed non-targeted, comprehensive metabolomic analysis to characterize metabolic signatures associated drought response in seedlings of Cenchrus spinifex Cav. (field sandbur), a highly invasive annual grass with heteromorphic, large and small seed types (M and P, respectively). We hypothesized that differences in metabolite production under drought between seed types could be a mechanism allowing it to successfully reproduce and adapt to high spatiotemporal heterogeneity within new environments. Seedlings generated from M and P seeds were exposed to three watering regimes equating to 65%-70% (W1), 45%-50% (W2), and 25%-30% (W3) soil water-holding capacity. After four weeks, ultrahigh performance liquid chromatography (UPLC) and tandem mass spectrometry (MS/MS) were used to identify and analyze metabolites in the fresh leaves. There were 27, 87 and 98 significantly different metabolites were identified in MW1 vs MW2, MW1 vs MW3 and MW2 VS MW3, respectively, and 34, 97 and 130 in PW1 vs PW2, PW1 vs PW3 and PW2 vs PW3. For different seed types, there were 54, 57 and 32 significantly different metabolites were identified in MW1 vs PW1, MW2 vs PW2 and MW3 VS PW3. These metabolites were annotated, classified, and analyzed by related pathways using the Kyoto Encyclopedia of Genes and Genomes (KEGG) and ultimately associated with lipid, amino acid, and flavonoid metabolism. Drought response was associated with downregulation of flavonoids and up-regulation of lipids within amino acids and linoleic acid metabolic pathways and differences between seed types was associated with downregulation of flavonoids and up-regulation of flavonoids within flavonoid metabolic pathways. Our study provides metabolomic insights into drought response in C. spinifex and suggests variation flavonoid metabolism among seed types could be an important mechanism enabling it to expand into drier environments in the future.