Protective role of exogenous polyamines on salinity‐stressed rice (Oryza sativa) plants

Abstract

Salt-tolerant Pokkali rice plants accumulate higher polyamines (PAs) such as spermidine (Spd) and spermine (Spm) in response to salinity stress, while the sensitive cultivarM-1-48 is unable to maintain high titres of these PAs under similar conditions. The effects of the triamine Spd and the tetramine Spm on physiological and biochemical changes in 12-day-old rice seedlings were investigated during salinity stress to determine whether they could protect the sensitive plants from stress effects. At physiological concentrations Spd and Spm significantly prevented the leakage of electrolytes and amino acids from roots and shoots induced by salinity stress. To different degrees they also prevented chlorophyll loss, inhibition of photochemical reactions of photosynthesis as well as downregulation of chloroplast-encoded genes like psbA, psbB, psbE and rbcL, indicating a positive correlation between salt tolerance and accumulation of higher PAs in rice. The inhibitory effect of salinity stress and its reversal by exogenous PAs were more pronounced in the salt-sensitiveM-1-48 plants than in the tolerant Pokkali plants.

Polyamines: potent modulators of plant responses to stress

“…Important role of Spm in conferring tolerance to salt stress was also reported in rice (Maiale et al 2004). Spd and Spm also significantly reduced the leakage of electrolytes and amino acids in roots and shoots of rice, subjected to saline stress and a positive correlation was established between salt tolerance and accumulation of higher levels of PAs (Chattopadhayay et al 2002). These findings were further strengthened from molecular studies that double knockout mutants of A. thaliana (acl5/spms) incapable of producing Spm, showed higher sensitivity to salt stress than wild type plants.…”

“…The antioxidative effect of PAs is due to a combination of their anion-and cation-binding properties involving a radical scavenging function (Bors et al 1989) and capability to inhibit both lipid peroxidation and metal-catalyzed oxidative reactions (Tadolini 1988). PAs have been tested as antioxidant in response to various abiotic stresses though their precise role as antioxidants but is still a matter of debate (Chattopadhayay et al 2002). Thus, a cellular defense mechanism of PA against oxidative stress attributed to the inhibition of lipid peroxidation, scavenging of oxygen radicals, and activation of gene expression for antioxidant enzymes.…”

Physiological adaptive mechanisms of plants grown in saline soil and implications for sustainable saline agriculture in coastal zone

“…Although many studies have announced that salt tolerance was enhanced in transgenic plants (Begcy et al 2011;Hao et al 2011;Jacobs et al 2011;Rahnama et al 2011;Wei et al 2011), the results are obtained under abnormal growth condition and not tested in the field. Stress resistance training and exogenous application of growth and osmotic regulators have been demonstrated to ameliorate plant salt stress (Amzallag et al 1990;Umezawa et al 2000;Chattopadhayay et al 2002;Demiral and Turkan 2006;Chen et al 2007;Kaya et al 2007;Wahid et al 2007;Athar et al 2008;Zheng et al 2008;Reezi et al 2009;Chang et al 2010;Cimrin et al 2010;Khan et al 2010;Akram and Ashraf 2011;Fan et al 2011;Idrees et al 2011;Lin et al 2011;Nazar et al 2011;Sakr et al 2012). These methods are derived from plant eco-physiology theories and are generalized in Table 1.…”

Effect of polyamines on somatic embryogenesis via mature embryo in wheat

“…This variation affects the use of tissue culture negatively in genetic transformation studies. Exogenous application of putrescine has been successfully used to enhance salinity (Chattopadhayay et al, 2002), cold (Nayyar and Chander, 2004), drought (Zeid and Shedeed, 2006), water logging (Arbona et al, 2008), and flooding tolerance of plants (Yiu et al, 2009). Polyamines are small, positively charged aliphatic amines at cellular pH values.…”