Journal
ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY
Volume 162, Issue -, Pages 312-323Publisher
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.ecoenv.2018.07.001
Keywords
Antioxidant enzymes; Ascorbate-glutathione cycle; Copper stress; Legume-rhizobium; Phytoremediation
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Funding
- National Key Research and Development Program of China [2016YFD0800706]
- National Natural Science Foundation of China (NSFC) [31501822, 41571314]
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Despite numerous reports that legume-rhizobium symbiosis alleviates Cu stress in plants, the possible roles of legume-rhizobium symbiosis and the regulatory mechanisms in counteracting Cu toxicity remain unclear. Here, Sinorhizobium meliloti CCNWSX0020 was used for analyzing the effects of rhizobium inoculation on plant growth in Medicago saliva seedlings under Cu stress. Our results showed that rhizobium inoculation alleviated Cu-induced growth inhibition, and increased nitrogen concentration in M. sativa seedlings. Moreover, the total amount of Cu uptake in inoculated plants was significantly increased compared with non-inoculated plants, and the increase in the roots was much higher than that in the shoots, thus decreasing the transfer coefficient and promoting Cu phytostabilization. Cu stress induced lipid peroxidation and reactive oxygen species production, but rhizobium inoculation reduced these components' accumulation through altering antioxidant enzyme activities and regulating ascorbate-glutathione cycles. Furthermore, legume-rhizobium symbiosis regulated the gene expression involved in antioxidant responses, phytochelatin (PC) biosynthesis, and metallothionein bio-synthesis in M. sativa seedlings under Cu stress. Our results demonstrate that rhizobium inoculation enhanced Cu tolerance by affecting Cu uptake, regulating antioxidant enzyme activities and the ascorbate-glutathione cycle, and influencing PC biosynthesis-related gene expression in M. sativa. The results provide an efficient strategy for phytoremediation of Cu-contaminated soils.
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