Double genetically modified symbiotic system for improved Cu phytostabilization in legume roots

• Published in: Environmental science and pollution research international Vol. 24; no. 17; pp. 14910 - 14923
• Main Authors: Pérez-Palacios, Patricia, Romero-Aguilar, Asunción, Delgadillo, Julián, Doukkali, Bouchra, Caviedes, Miguel A., Rodríguez-Llorente, Ignacio D., Pajuelo, Eloísa
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.06.2017; Springer Nature B.V
• Subjects: Alfalfa; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Biotechnology; Copper; Copper - pharmacokinetics; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental science; Genetic modification; Inoculation; Legumes; Lipid peroxidation; Malondialdehyde; Medicago truncatula; Metallothionein; Metals; Nodulation; Oxidative stress; Peroxidation; Plant growth; Plant Roots; Plants (botany); Plants, Genetically Modified; Pseudomonas fluorescens; Reactive oxygen species; Research Article; Rhizobium; Roots; Shoots; Symbionts; Symbiosis; Thiobarbituric acid; Translocation; Waste Water Technology; Water Management; Water Pollution Control; Copper; Heavy metals; Phytoremediation; Medicago truncatula; copAB; mt4a; Ensifer (Sinorhizobium) medicae
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-017-9092-4

Excess copper (Cu) in soils has deleterious effects on plant growth and can pose a risk to human health. In the last decade, legume-rhizobium symbioses became attractive biotechnological tools for metal phytostabilization. For this technique being useful, metal-tolerant symbionts are required, which can be generated through genetic manipulation. In this work, a double symbiotic system was engineered for Cu phytostabilization: On the one hand, composite Medicago truncatula plants expressing the metallothionein gene mt4a from Arabidopsis thaliana in roots were obtained to improve plant Cu tolerance. On the other hand, a genetically modified Ensifer medicae strain, expressing copper resistance genes copAB from Pseudomonas fluorescens driven by a nodulation promoter, nifHp , was used for plant inoculation. Our results indicated that expression of mt4a in composite plants ameliorated plant growth and nodulation and enhanced Cu tolerance. Lower levels of ROS-scavenging enzymes and of thiobarbituric acid reactive substances (TBARS), such as malondialdehyde (a marker of lipid peroxidation), suggested reduced oxidative stress. Furthermore, inoculation with the genetically modified Ensifer further improved root Cu accumulation without altering metal loading to shoots, leading to diminished values of metal translocation from roots to shoots. The double modified partnership is proposed as a suitable tool for Cu rhizo-phytostabilization.