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Publication Type J
Authors Paredes-Paliz, K., R. Rodriguez-Vazquez, B. Duarte, M. A. Caviedes, E. Mateos-Naranjo, S. Redondo-Gomez, M. I. Cacador, I. D. Rodriguez-Llorente and E. Pajuelo
Title Investigating the mechanisms underlying phytoprotection by plant growth-promoting rhizobacteria in Spartina densiflora under metal stress
Source Plant Biology
Author Keywords Heavy metal stress PGPR-halophyte interaction phenylalanine ammonia lyase ROS scavenging enzymes thiobarbituric acid reactive substances phenylalanine ammonia-lyase oryza-sativa l. photosynthetic responses invasive cordgrass salt marshes plaque-formation gene-expression mine drainage heavy-metals tolerance
Abstract Pollution of coasts by toxic metals and metalloids is a worldwide problem for which phytoremediation using halophytes and associated microbiomes is becoming relevant. Metal(loid) excess is a constraint for plant establishment and development, and plant growth promoting rhizobacteria (PGPR) mitigate plant stress under these conditions. However, mechanisms underlying this effect remain elusive. The effect of toxic metal(loid)s on activity and gene expression of ROS-scavenging enzymes in roots of the halophyte Spartina densiflora grown on real polluted sediments in a greenhouse experiment was investigated. Sediments of the metal-polluted joint estuary of Tinto and Odiel rivers and control, unpollutred samples from the Piedras estuary were collected and submitted to ICP-OES. Seeds of S.densiflora were collected from the polluted Odiel marshes and grown in polluted and unpolluted sediments. Rhizophere biofilm-forming bacteria were selected based on metal tolerance and inoculated to S.densiflora and grown for 4months. Fresh or frozen harvested plants were used for enzyme assays and gene expression studies, respectively. Metal excess induced SOD (five-fold increase), whereas CAT and ascorbate peroxidase displayed minor induction (twofold). A twofold increase of TBARs indicated membrane damage. Our results showed that metal-resistant PGPR (P.agglomerans RSO6 and RSO7 and B.aryabhattai RSO25) contributed to alleviate metal stress, as deduced from lower levels of all antioxidant enzymes to levels below those of non-exposed plants. The oxidative stress index (OSI) decreased between 50 and 75% upon inoculation. The results also evidenced the important role of PAL, involved in secondary metabolism and/or lignin synthesis, as a pathway for metal stress management in this halophyte upon inoculation with appropriate PGPR, since the different inoculation treatments enhanced PAL expression between 3.75- and five-fold. Our data confirm, at the molecular level, the role of PGPR in alleviating metal stress in S.densiflora and evidence the difficulty of working with halophytes for which little genetic information is available.
Author Address [Paredes-Paliz, K.; Rodriguez-Vazquez, R.; Caviedes, M. A.; Rodriguez-Llorente, I. D.; Pajuelo, E.] Univ Seville, Fac Farm, Dept Microbiol & Parasitol, C Prof Garcia Gonzalez 2, E-41012 Seville, Spain. [Duarte, B.; Cacador, M. I.] Univ Lisbon, MARE Marine & Environm Sci Ctr, Fac Sci, Lisbon, Portugal. [Mateos-Naranjo, E.; Redondo-Gomez, S.] Univ Seville, Fac Biol, Dept Biol Vegetal & Ecol, Seville, Spain. Pajuelo, E (reprint author), Univ Seville, Fac Farm, Dept Microbiol & Parasitol, C Prof Garcia Gonzalez 2, E-41012 Seville, Spain. epajuelo@us.es
ISSN 1435-8603
ISBN 1435-8603
29-Character Source Abbreviation Plant Biol.
Publication Date May
Year Published 2018
Volume 20
Issue 3
Beginning Page 497-506
Digital Object Identifier (DOI) 10.1111/plb.12693
Unique Article Identifier WOS:000430010500012
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