Plant root exudates drive changes in rhizobacterial gene expression: effects on hydrocarbon degradation and plant growth-promoting rhizobacteria traits in rhizoremediation

作者：Melissa Uribe, G. Peñuela, Nancy J. Pino · 发表于：Journal of Soils and Sediments · 年份：2026 · DOI：10.1007/s11368-026-04269-x · 被引用次数：2

Rhizoremediation leverages plant–microbe interactions to restore hydrocarbon-contaminated soils. However, the molecular mechanisms that mediate these interactions remain poorly understood. This study aimed to investigate how tropical grasses and their root exudates modulate rhizobacterial gene expression related to hydrocarbon degradation and plant growth promotion, providing functional insights to optimize rhizoremediation strategies. A greenhouse pot experiment was conducted using petroleum-contaminated soil planted with Brachiaria decumbens and Megathyrsus maximus. Total petroleum hydrocarbon (TPH) removal and soil physicochemical parameters were evaluated after 3 months. Rhizospheric soil was analyzed for expression of six functional genes (alkB, alkB2, P450, rhlA, nifH, and gcd) by qRT-PCR. A complementary microcosm assay was performed to assess gene expression responses to individual and mixed root exudate analogs (sucrose, citric acid, oxalic acid, glutamic acid, flavanone, isoflavone) at days 7 and 15. Statistical comparisons were conducted using ANOVA or non-parametric equivalents, and integrative multivariate analyses were applied to explore associations between gene expression and soil quality indicators. Megathyrsus maximus showed the highest TPH removal (41.47%) and improved soil properties, including pH, porosity, cation exchange capacity, and nutrient availability. Gene expression analyses revealed upregulation of alkB2 and P450 in vegetated soils, while alkB r...