title: Analysis of DNA methylation of maize in response to osmotic and salt stress based on methylation-sensitive amplified polymorphism.
abstract: Water stress is known to alter cytosine methylation, which generally represses transcription. However, little is known about the role of methylation alteration in maize under osmotic stress. Here, methylation-sensitive amplified polymorphism (MSAP) was used to screen PEG- or NaCl-induced methylation alteration in maize seedlings. The sequences of 25 differentially amplified fragments relevant to stress were successfully obtained. Two stress-specific fragments from leaves, LP166 and LPS911, shown to be homologous to retrotransposon Gag-Pol protein genes, suggested that osmotic stress-induced methylation of retrotransposons. Three MSAP fragments, representing drought-induced or salt-induced methylation in leaves, were homologous to a maize aluminum-induced transporter. Besides these, heat shock protein HSP82, Poly [ADP-ribose] polymerase 2, Lipoxygenase, casein kinase (CK2), and dehydration-responsive element-binding (DREB) factor were also homologs of MSAP sequences from salt-treated roots. One MSAP fragment amplified from salt-treated roots, designated RS39, was homologous to the first intron of maize protein phosphatase 2C (zmPP2C), whereas - LS103, absent from salt-treated leaves, was homologous to maize glutathione S-transferases (zmGST). Expression analysis showed that salt-induced intron methylation of root zmPP2C significantly downregulated its expression, while salt-induced demethylation of leaf zmGST weakly upregulated its expression. The results suggested that salinity-induced methylation downregulated zmPP2C expression, a negative regulator of the stress response, while salinity-induced demethylation upregulated zmGST expression, a positive effecter of the stress response. Altered methylation, in response to stress, might also be involved in stress acclimation.
authors.affiliation: College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China. tempo@njau.edu.cn
authors.forename: Ming-pu
authors.initials: MP
authors.lastname: Tan
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D000595:Amino Acid Sequence; D054458:Amplified Fragment Length Polymorphism Analysis; D019175:DNA Methylation / Q000502:physiology*; D003890:Desiccation; D055864:Droughts; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D007438:Introns; D009997:Osmotic Pressure; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves; D011092:Polyethylene Glycols; D011110:Polymorphism, Genetic; D000071636:Protein Phosphatase 2C; D018626:Retroelements; D055049:Salt Tolerance / Q000235:genetics; D012965:Sodium Chloride; D013312:Stress, Physiological; D003313:Zea mays / Q000235:genetics* / Q000378:metabolism
chemical_list: D018626:Retroelements; D011092:Polyethylene Glycols; D012965:Sodium Chloride; D005982:Glutathione Transferase; D010749:Phosphoprotein Phosphatases; D000071636:Protein Phosphatase 2C