biologia plantarum

Biologia plantarum 52:668-673, 2008 | DOI: 10.1007/s10535-008-0129-x

Characterization of a rice metallothionein type 3 gene with different expression profiles under various nitrogen forms

G. H. Zhu¹, J. J. Zhang¹, J. S. Chen¹, X. X. Peng^1,*

¹ College of Life Science, South China Agricultural University, Guangzhou, P.R. China

A cDNA sequence OsMT3 was initially isolated from the subtractive cDNA library of ammonium-fed rice (Oryza sativa L.) leaves, which was further confirmed by Northern blot to be highly ammonium-up-regulated as compared to nitrate. Its full-length cDNA was cloned by RT-PCR, and in silico analysis reveals that the cDNA includes an open reading frame of 186 bp and encodes a rice metallothionein type 3 peptide. Northern blotting analysis showed that OsMT3 gene predominantly expressed in rice leaves, weakly in stems, and barely in buds and roots. The gene transcripts in leaves were significantly induced by polyethylene glycol (PEG), low temperature, NaCl and Cu²⁺, but not by Pb²⁺. Activities of three anti-oxidative enzymes (superoxide dismutase, catalase and peroxidases) and two non-enzymic antioxidants (reduced ascorbate and reduced glutathione) little differed in ammonium-and nitrate-fed rice leaves, indicating that the induced OsMT3 expression was not mediated by ammonium-elicited oxidative signals.

Keywords: ammonium; nitrate; Oryza sativa; OsMT3 gene; oxidative stress

Subjects: amino acids; antioxidants, antioxidant enzymes; ascorbate peroxidase; catalase; cDNA sequence; glutathione reductase; in vitro culture, regeneration; in vitro culture, rooting; Oryza sativa; peroxidase; polymerase chain reaction (PCR); rice; salinity, salt stress; temperature, low

Received: January 22, 2007; Accepted: August 8, 2007; Published: December 1, 2008  Show citation