Epigenetic control of heavy metal stress response in mycorrhizal versus non-mycorrhizal poplar plants
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It was previously shown that arbuscular mycorrhizal fungi (AMF) exert a significant improvement of growth in a tolerant white poplar (Populus alba L.) clone (AL35) grown on Cu- and Zn-polluted soil via foliar alterations in the levels of defence/stress-related transcripts and molecules. However, nothing is known about the epigenetic changes which occur during tolerance acquisition in response to heavy metals (HMs) in the same mycorrhizal vs. non-mycorrhizal poplar plants. In order to analyse the epigenome in leaves of AL35 plants inoculated or not with AMF and grown in a greenhouse on multimetal polluted or unpolluted soil, the Methylation Sensitive Amplification Polymorphism (MSAP) approach was adopted to detect cytosine DNA methylation. Modest changes in cytosine methylation patterns were detected at first sampling (4 months from planting), whereas extensive alterations (hypomethylation) occurred at second sampling (after 6 months) in mycorrhizal plants grown in the presence of HMs. The sequencing of MSAP fragments led to the identification of genes belonging to several Gene Ontology categories. Seven MSAP fragments, selected on the basis of DNA methylation status in treated vs control AL35 leaves at the end of the experiment, were analysed for their transcript levels by means of qRT-PCR. Gene expression varied in treated samples relative to controls in response to HMs and/or AMF inoculation; in particular, transcripts of genes involved in RNA processing, cell wall and amino acid metabolism were upregulated in the presence of AMF with or without HMs.
KeywordsArbuscular mycorrhizal fungi DNA methylation Epigenome Heavy metals MSAP technique Poplar
This research was supported by funds from the Italian Ministry for Education, University and Scientific Research (PRIN 2003077418) and from the Italian Ministry of Environment, Land and Sea Protection (‘Research and development in biotechnology applied to the protection of the environment’ in collaboration with The People’s Republic of China) to S.C., and it is also part of the doctorate carried out by A.C. at the Federico II University of Naples (IT).
- Arsova B, Hoja U, Wimmelbacher M, Greiner E, Uestuen S, Melzer M, Petersen K, Lein W, Boernke F (2010) Plastidial thioredoxin z interacts with two fructokinase-like proteins in a thiol-dependent manner: evidence for an essential role in chloroplast development in Arabidopsis and Nicotiana benthamiana. Plant Cell 22:1498–1515CrossRefGoogle Scholar
- Christophersen H.M., Smith F.A. & Smith S.E. (2012) Unraveling the influence of Arbuscular Mycorrhizal colonization on arsenic olerance in medicago: Glomus mosseae is more effective than G. intraradices, associated with lower expression of root epidermal Pi transporter genes. Frontiers in physiology 3, 91Google Scholar
- Cicatelli A, Lingua G, Todeschini V, Biondi S, Torrigiani P, Castiglione S (2010) Arbuscular mycorrhizal fungi restore normal growth in a white poplar clone grown on heavy metal-contaminated soil, and this is associated with upregulation of foliar metallothionein and polyamine biosynthetic gene expression. Ann Bot 106:791–802CrossRefGoogle Scholar
- Gao L, Geng Y, Li B, Chen J, Yang J (2010) Genome-wide DNA methylation alterations of Alternanthera philoxeroides in natural and manipulated habitats: implications for epigenetic regulation of rapid responses to environmental fluctuation and phenotypic variation. Plant Cell Environ 33:1820–1827CrossRefGoogle Scholar
- Jaccard P (1908) Nouvelles recherches sur la distribution florale. Bulletin des Société Vaudoise des Sciences Naturelles 44:223–270Google Scholar
- Lira-Medeiros CF, Parisod C, Fernandes RA, Mata CS, Cardoso MA, Gomes Ferreira PC (2010) Epigenetic variation in mangrove plants occurring in contrasting natural environment. Plos One 5Google Scholar
- Mittenhuber G (2001) Phylogenetic analyses and comparative genomics of vitamin B-6 (pyridoxine) and pyridoxal phosphate biosynthesis pathways. J Mol Microbiol Biotechnol 3:1–20Google Scholar
- Peng H, Zhang J (2009) Plant genomic DNA methylation in response to stresses: potential applications and challenges in plant breeding. Proc Natl Acad Sci U S A 19:1037–1045Google Scholar
- Schüßler A. & Walker C. (2012) The Glomeromycota: a species list with new families and genera. The Royal Botanic Garden Edinburgh, The Royal Botanic Garden Kew, Botanische Staatssammlung Munich, Oregon State University, Edinburgh, UK; London, UK; Munich, D; Corvallis, Oregon-US.Google Scholar
- Steward N, Kusano T, Sano H (2000) Expression of ZmMET1, a gene encoding a DNA methyltransferase from maize, is associated not only with DNA replication in actively proliferating cells, but also with altered DNA methylation status in cold-stressed quiescent cells. Nucleic Acids Res 28:3250–3259CrossRefGoogle Scholar
- Zhao GS, Winkler ME (1995) Kinetic limitation and cellular amount of pyridoxine (pyridoxamine) 5′-phosphate oxidase of Escherichia coli K-12. J Bacteriol 177:883–891Google Scholar