Development of transgenic hybrid sweetgum (Liquidambar styraciflua × L. formosana) expressing γ-glutamylcysteine synthetase or mercuric reductase for phytoremediation of mercury pollution
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Using Agrobacterium-mediated gene transfer, we generated transgenic hybrid sweetgum (Liquidambar styraciflua × L. formosana) overexpressing two types of genes to enhance plant remediation of mercury-contaminated soil and water: bacterial γ-glutamylcysteine synthetase gene (ECS), the first and most important enzyme in phytochelatin synthesis, or various genes encoding a mercuric ion reductase (merA9, merA18, merA77). Hybrid sweetgum proembryogenic masses (PEMs) constitutively overexpressing ECS were able to grow in the presence of 50 μM HgCl2, which inhibited wild-type PEMs, but plantlets regenerated from the PEMs had abnormal form and did not survive for more than a few weeks following germination. In contrast, mature somatic embryos generated from PEMs constitutively overexpressing merA9 and merA18 converted to normal plantlets on germination medium containing 25 μM HgCl2, while control embryos were killed on 25 μM Hg(II)-medium. Transgenic merA plantlets displayed enhanced resistance to Hg(II) and released Hg(0) two to three times more efficiently than the wild-type plantlets.
KeywordsPhytoremediation Mercury Liquidambar styraciflua × L. formosana Transgenic
This research was supported in part by the Consortium for Plant Biotechnology Research, Inc. by DOE Prime Agreement No. DE-FC05-92OR22072. This support does not constitute an endorsement by DOE or by the Consortium for Plant Biotechnology Research, Inc. of the views expressed in this publication. We thank Dr. Daniel Carraway (International Paper Co.) for sharing his protocol for sweetgum transformation, Dr. Yujing Li, Dr. Joe Nairn and Dr. Andrew Heaton for advice, and Mandy Beggs, Lihua Wang, Amparo Lima and Xiuqin Xia for technical assistance.
- Chen ZZ, Stomp AM (1991) Transformation of Liquidambar styraciflua L. (sweetgum) using Agrobacterium tumefaciens. (Abstract) In: Proceedings of the 21st southern tree improvement conference, Knoxville, TN, 17–20 June 1991, p 315Google Scholar
- Cobbett C, Meagher R (2003) Phytoremediation and the Arabidopsis proteome. In: Meyerowitz E, Somerville C (eds) Arabidopsis. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, pp 1–22Google Scholar
- Dhankher OP, Li Y, Rosen BP, Shi J, Salt D, Senecoff JF, Sashti NA, Meagher RB (2002) Engineering tolerance and hyperaccumulation of arsenic in plants by combining arsenate reductase and γ-glutamylcysteine synthetase expression. Nat Biotechnol 20:1140–1145. doi:10.1038/nbt747 PubMedCrossRefGoogle Scholar
- Harlow WM, Harrar ES, Hardin JW, White FM (1996) Textbook of dendrology, 8th edn. McGraw-Hill, New YorkGoogle Scholar
- Li Y, Dhankher OP, Carreira L, Smith AP, Meagher RB (2006b) The shoot-specific expression of γ−glutamylcysteine synthetase directs the long-distance transport of thiol-peptides to roots conferring tolerance to mercury and arsenic. Plant Physiol 141:288–298. doi:10.1104/pp.105.074815 PubMedCrossRefGoogle Scholar
- Meagher RB (2007) Multigene strategies for engineering the phytoremediation of mercury and arsenic. In: Xu Z, Li J, Xue Y, Yang W (eds) Biotechnology and sustainable agriculture 2006 and beyond: proceedings of the 11th IAPTC&B congress. Springer, Beijing, China, pp 49–60Google Scholar
- Peuke AD, Rennenberg H (2005) Phytoremediation with transgenic trees. Z Naturforsch 60:199–207Google Scholar
- Sambrook J, Fritsch EF, Maniatis T (1989) Molecular cloning-a laboratory manual. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NYGoogle Scholar
- Stomp AM, Han KH, Wilbert S, Gordon MP (1993) Genetic improvement of tree species for remediation of hazardous wastes. In Vitro Cell Dev Biol 29P:227–232Google Scholar