Superoxide dismutase: an all-purpose gene for agri-biotechnology

Abstract

The objective of this study was to evaluate the performance of transgenic canola (Brassica napus) plants over-expressing a wheat mitochondrial Mn superoxide dismutase (Mn SOD3.1) subjected to environmental stresses in the field and in controlled environments. Mn SOD3.1 was regulated by either CaMV 35S or Arabidopsis COR78 promoters. RT-PCR and a SOD enzyme activity assays demonstrated Mn SOD3.1 was expressed at both the mRNA and protein levels. Enzyme activity assays exhibited total SOD activity was up to 41.8% and up to 26.7% higher in the 35S:SOD3.1 and in the COR78:SOD3.1 transgenic plants than in the control, respectively. Germination studies, conducted at suboptimal (8°C) and optimal (23°C) temperatures, identified transgenic lines that germinated earlier than the control. In the field under drought conditions, several transgenic lines emerged earlier than the control. In both greenhouse and field environments, several transgenic lines were significantly taller than the control and over 50% of the transgenic canola lines flowered 7–14 days earlier than the control. Over expression of Mn SOD3.1 enhanced heat, drought and cold tolerance both in the field and under artificial stress conditions. This is one of the first tests conducted on transgenic canola plants subjected to field conditions.