Expression analysis of type 2 metallothionein gene in mangrove species (Bruguiera gymnorrhiza) under heavy metal stress.

In this paper, we aimed to assess the roles of metallothioneins (MTs) in heavy metal tolerance by analyzing the expression level of BgMT2 in leaves of Bruguiera gymnorrhiza in response to heavy metals. Eight-month-old B. gymnorrhiza seedlings were exposed to different concentrations of zinc (Zn), copper (Cu) or lead (Pb) for 1, 3 and 7 d. A Real-time quantitative PCR protocol was developed to directly evaluate the expression of BgMT2, using 18S rRNA as a reference gene. Real-time quantitative PCR analysis demonstrated BgMT2 mRNA expression was regulated by Zn, Cu and Pb, but the regulation pattern was different for the three metals tested. Significant increase in the transcript level of BgMT2 was also found in response to Zn, Cu and Pb in some experimental conditions. Our results confirm that BgMT2 gene is involved in the regulation of Zn, Cu and Pb in B. gymnorrhiza leaves.