National Agricultural Science and Technology Jiangsu Innovative Center

Nanjing, China

National Agricultural Science and Technology Jiangsu Innovative Center

Nanjing, China

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Chang Y.H.,Jiangsu Academy of Agricultural Sciences | Chang Y.H.,National Agricultural Science and Technology Jiangsu Innovative Center | Li H.,Jiangsu Academy of Agricultural Sciences | Li H.,National Agricultural Science and Technology Jiangsu Innovative Center | And 3 more authors.
Plant Molecular Biology Reporter | Year: 2012

Phytochelatins play a major role in metal detoxification in plants. However, the molecular mechanisms of heavy metal detoxification remain unknown, and birch-leaf pear genes related to metal detoxification have not yet been identified. Here, we report the isolation of cDNA and genomic DNA sequences encoding a phytochelatin synthase (PCS) from birch-leaf pear (Pyrus betulaefolia Bunge). The PbPCS1 cDNA sequence contained 1,965 nucleotides of a 1,494 bp open reading frame (ORF), which encodes a 497-amino-acid protein with a molecular weight of 55. 00 kDa. Its corresponding genomic DNA sequence consists of 3,820 nucleotides and eight exons separated by seven introns. The deduced amino acid sequence of PbPCS1 contains five Cys residues (56, 90, 91, 109 and 113 amino acids) that are highly conserved in the plant PCS1 family, and 12 cysteine residues putatively involved in heavy metal binding sites, which included three adjacent Cys-Cys components (331-332, 351-352 and 369-370 amino acids) in the C-terminal variable domain. Homology analysis of the deduced PbPCS1 amino acid sequence revealed that it shares a high sequence similarity amongst N-terminal amino acids and low similarity with C-terminal amino acids with plant PCS1 proteins deposited with NCBI. PbPCS1 was most related to PCS1 from legume plants Lotus japonicus (GenBank accession no. AAT80342) and soybean (Glycine max L.; AAL78384) as they were clustered into the same clade in a neighbor-joining phylogenetic tree. Quantitative real-time PCR (qPCR) expression analysis revealed that PbPCS1 had a very low basal expression level in untreated whole seedlings, and levels were higher in roots than in leaves and stems. After 24 h of exposure to 20 μM CdSO 4, CuSO 4 or ZnSO 4, PbPCS1 expression increased significantly in different organs. In addition, L-buthionine-sulfo-ximine (BSO) can inhibit PbPCS1 expression in roots, stems and leaves, while L-glutathionereduced (GSH) stimulates PbPCS1 expression in different organs of birch-leaf pear. © 2012 Springer-Verlag.


Li H.,Jiangsu Academy of Agricultural Sciences | Li H.,National Agricultural Science and Technology Jiangsu Innovative Center | Cong Y.,CAS Nanjing Institute of Soil Science | Chang Y.-H.,Jiangsu Academy of Agricultural Sciences | And 3 more authors.
Zhiwu Shengli Xuebao/Plant Physiology Journal | Year: 2012

N-methylation of phosphoethanolamine, the committing step in choline biosynthesis in plants, is catalyzed by phosphoethanolamine N-methyltransferase (PEAMT, EC 2.1.1.103). Herein we report the cloning and characterization of a novel birch-leaf pear (Pyrus betulaefolia) phosphoethanolamine N-methyltransferase gene (PbPEAMT) using a combination of homologous cloning, PCR and bioinformatics strategy. At the same time, semi-quantitative PCR with cross-intron primers was adopted to study the expression features of this gene under abiotic stresses. The results showed that the DNA sequence of PbPEAMT gene is 3320 bp, which consists of 11 exons and 10 introns. The cDNA sequence of PbPEAMT gene is 1 479 bp in length and encodes a 492-amino-acid peptide, which includes two conserved motifs of type II methyltransferase. Homology analysis showed that the deduced PbPEAMT protein was highest homologous to castor PEAMT protein (86%). Furthermore, PbPEAMT was more related to castor PEAMT through phylogenetic analysis. RT-PCR analysis showed that expression of PbPEAMT was induced by 100 mmol·L-1 NaCl, 10% (W/V) PEG6000, 180 mmol · L-1 mannitol or 20 μmol · L-1 ABA treatments. These data indicate that PbPEAMT expression responds to salinity, drought and osmotic stresses, which may be involved in ABA-mediated stress signal transduction pathway.

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