ABSTRACT
Keywords: Polyamines, Putrescine, Salinity stress, Spermidine, Spermine, Transgenic plants
The major challenging task of world agriculture is to produce 70% more food for an additional 2.3 billion people by 2050 (FAO 2009). The average
yield of major crops have decreased by 70% in the past decade due to adverse effect of abiotic stresses (Gosal et al. 2009). Maintaining crop yields under adverse environmental stresses is
13.1 Introduction / 241 13.2 Salinity Stress Response / 242 13.3 Polyamines in Relation to Plant Stress / 243 13.4 Polyamine Biosynthesis and Catabolism in Plants / 244 13.5 Accumulative and Protective Role of Polyamines under Saline Stress / 244 13.6 Transgenic Studies / 246 13.7 Conclusions / 247 References / 247
probably the major challenge of modern agriculture (Gill and Tuteja 2010). In the recent years, one of the main causes of lower crop productivity is mostly accredited by various abiotic stresses, and it is an important area of concern to switch the increasing food requirements (Shanker and Venkateswarlu 2011). The major abiotic stress factors limiting crop productivity and threatening food security are soil salinity, exposure to high and low temperatures, and drought (Mantri et al. 2012). Among the abiotic stresses, soil salinity is one of the most ruthless environmental factors and a complex phenotypic and physiological phenomenon in plants and imposing ion imbalance or disequilibrium, and hyperionic and hyperosmotic stress. It is disrupting the overall metabolic activities that limit crop productivity worldwide (Munns and Tester 2008; Flowers et al. 2010). Saline soils occupy more than 10% of the land surface and 50% of all irrigated land (Ruan et al. 2010). Soil salinity represents a major limiting factor in decreasing more than 20% worldwide crop production under irrigated land, while more than 40% worldwide irrigated land has already been damaged by salt (Porcel et al. 2012).
