Genes induced in response to mercury-ion-exposure in heavy metal hyperaccumulator Sesbania drummondii.
Sesbania drummondii plants have been recognized as a potential mercury (Hg) hyperaccumulator. To identify genes modulated by Hg, two suppressive subtraction hybridization (SSH) cDNA libraries (forward and reverse) were constructed. A total of 348 differentially expressed clones were isolated and 95 of them were identified as Hg responsive. Reverse Northern results showed that 31 clones from forward library were down-regulated and 64 clones from reverse library were up-regulated in Hg-treated plants. Sixty-seven of them showed high homology to genes with known or putative function, and 28 were uncharacterized genes. Two full-length cDNAs coding for a putative metallothionein type 2 protein (SdMT2) and an auxin responsive protein (SdARP) were isolated and characterized. The expression levels of SdMT2 and SdARP increased 3- and 5-fold, respectively. Results suggest that up-regulated expression of SdARP may contribute to the survival of Sesbania plants under mercury stress, whereas SdMT2 is likely to be involved in alleviation of Hg toxicity. The possible correlation between gene expression and heavy metal tolerance of Sesbania plants is discussed.
Venkatachalam
P
P
Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907, USA.
Srivastava
A K
AK
Raghothama
K G
KG
Sahi
S V
SV
D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D017931:DNA Primers; D018076:DNA, Complementary; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D017343:Genes, Plant; D008628:Mercury / Q000633:toxicity*; D008668:Metallothionein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019216:Metals, Heavy / Q000378:metabolism*; D008969:Molecular Sequence Data; D010788:Photosynthesis / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D049931:Sesbania / Q000235:genetics* / Q000378:metabolism
D017931:DNA Primers; D018076:DNA, Complementary; D019216:Metals, Heavy; D008668:Metallothionein; D008628:Mercury