Development and characterization of transgenic potato plants with enhanced tolerance to multiple environmental stresses

Abstract

Environmental problems caused by pollution, global warming and desertification of lands are becoming major limiting factors for food security in future. Environmental stresses are major cause of low crop productivity worldwide and they can reduce the average crop yield by more than 50%. So, it becomes imperative to use the advances made in the field of plant biotechnology to develop such crops that can tolerate the elevated environmental stresses. Potato is one of the major food crops in many parts of the world and it is being consumed on daily basis. Although potato production is increasing in developing countries but still the production is low due to environmental stresses and there is a big need to develop such cultivars with improved tolerance against environmental stresses by molecular breeding technology. In this study, we developed transgenic potato plants (cv. Superior) with enhanced tolerance to environmental stresses by overexpression of $codA$ alone (referred to as SC plants) and in combination with Cu/Zn SOD and APX (referred to as SSAC plants) in chloroplasts under the control of stress-inducible $SWPA2$ promoter. The stress induced induction of $codA$ gene in SC and SSAC plants resulted in glycinebetaine (GB) synthesis. GB synthesis resulted in enhanced tolerance of SC plants to oxidative, salt and drought stresses. We also observed synergistic effects of GB, APX and SOD in SSAC plants. SSAC plants exhibited enhanced tolerance to oxidative stress and maintained higher antioxidative enzyme activities than NT and SAA plants. In addition to this, we have developed selection marker free plants with enhanced tolerance to environmental stresses. These marker free plants were developed by overexpresing pea SOD and APX in the chloroplasts (SSAF plants) under the control of stress-inducible $SWPA2$ promoter. SSAF plants showed enhanced tolerance to MV-mediated oxidative stress and high temperature stress as compared to non-transgenic plants...