Molecular orchestration of central metabolism as an adaptation strategy in plants under biotic and abiotic stresses

Abstract

Global food security and agricultural sustainability depend on a deep understanding of how plants manage energy and molecular resources under adverse environmental conditions. This thesis investigates the mechanisms of plant resilience through a systems biology approach, integrating high-throughput transcriptomics and metabolomics to decipher responses to biotic and abiotic stresses in three distinct models: the potential halophyte Gliricidia sepium, the halophyte Portulaca oleracea, and the perennial crop Elaeis guineensis. The first chapter investigates the temporal dynamics of extreme salinity tolerance in G. sepium, highlighting a biphasic metabolic alternation. It is observed that the plant transitions from an initial state of carbon conservation, mediated by β-oxidation of lipids, to a high-throughput adaptation phase characterized by the reactivation of glycolysis and the TCA cycle, orchestrated by specific isoforms of the enzyme fructose-1,6-bisphosphate aldolase (FBPA). Complementing this temporal perspective, the second chapter explores organ-specific regulation in P. oleracea, highlighting a molecular division of labor where roots prioritize bioenergetic input for ionic homeostasis, while leaves reprogram lipid metabolism to mitigate oxidative damage, under the governance of distinct gene regulatory networks (GRNs) led by the bHLH, B3, and bZIP families. Expanding the analysis to biotic stress, the third chapter presents a multi-omics deconstruction of Red Ring Disease in oil palm. Through the integration of RNA-Seq and metabolomics data, specific biomarkers for the detection of the nematode Bursaphelenchus cocophilus are identified, and crucial metabolic pathways of the host plant are mapped, providing strategic genetic targets for the development of resistant varieties via gene editing. Collectively, these studies demonstrate that plant resilience is not a static attribute, but an emergent property of metabolic plasticity and the precise coordination between tissues and carbon flows. By investigating biotic and abiotic stresses, this thesis establishes a robust scientific basis for precision breeding, offering integrated biotechnological solutions for agriculture in marginal environments and under increasing pathogenic pressure.