Tropentag, September 20 - 22, 2017 in Bonn "Future Agriculture: Social-ecological transitions and bio-cultural shifts"

Evaluation of Cd²⁺ Stress Tolerance in Transgenic Rice by Overexpressing PgGPx Gene that Maintains Cellular Ion and Reactive Oxygen Species Homeostasis

¹University of Dhaka, Dept. of Botany, Bangladesh
²International Centre for Genetic Engineering and Biotechnology, Plant Molecular Biology, Bangladesh

Abstract

Increasing contamination and higher enrichment ratio of non-essential heavy metals induce various toxic responses in plants when accumulated above the threshold level. These effects and growth responses are genotype and heavy metal level dependent. Cadmium, a non-essential toxic heavy metal, interferes with the plant growth and development. It reaches the leave through xylem and may become part of the food chain, thus causing detrimental effect to human health. Therefore, there is an urgent need to develop strategies for engineering plants for Cd²⁺ tolerance and less accumulation. Plant species generate a range of defense mechanisms to resist Cd²⁺ induced toxicity and to recover the subsequent damages eliciting their genotype based biochemical responses. To counter damages plants have an efficient system of stress enzymes and antioxidant non-enzyme molecules that is termed as antioxidant system. The members of peroxidase family of antioxidant system, transport metal ions including Cd²⁺, and thus play important role an ion homeostasis. The present study elucidates the role of a Pennisetum glutathione peroxidase (PgGPx) in Cd²⁺ stress tolerance. Transgenic rice expressing PgGPx showed tolerance towards Cd²⁺ stress as demonstrated by several physiological indices including root length, biomass, chlorophyll, malondialdehyde and hydrogen peroxide content. Roots of the transgenic lines accumulated more Cd²⁺ as compared to shoot. PgGPx expression in rice also protected the transgenic plants from oxidative stress by enhancing the activity of antioxidant enzymatic (SOD, CAT, APX, GR) machinery. Thus, overexpression of PgGPx confers Cd²⁺ stress tolerance in transgenic lines by maintaining cellular ion homeostasis and modulating reactive oxygen species (ROS)-scavenging pathway. Thus, the present study will help to develop strategies for engineering Cd²⁺ stress tolerance in economically important crop plants.

Keywords: Cd²⁺ stress, PgGPx, rice, ROS

Contact Address: Tahmina Islam, University of Dhaka, Dept. of Botany, 1000 Dhaka, Bangladesh, e-mail: subarna.islamgmail.com