Protective effects of proline against cadmium toxicity in micropropagated hyperaccumulator, Solanum nigrum L.

Abstract

Solanum nigrum is a newly discovered Cd-hyperaccumulator. In the present study, the protective effects of proline against cadmium toxicity of callus and regenerated shoots of S. nigrum are investigated based on a high frequency in vitro shoot regeneration system. Proline pretreatment reduces the reactive oxygen species levels and protects the plasma membrane integrity of callus under cadmium stress, and therefore improves the cadmium tolerance in S. nigrum. Inductively coupled plasma mass spectroscopy analysis shows that exogenous proline increases the cadmium accumulation in callus and regenerated shoots of S. nigrum. Further analysis indicates that the improvement of cadmium tolerance caused by proline pretreatment is correlated with an increase of superoxide dismutase and catalase activity and intracellular total glutathione content. The interaction between proline and enzymic or non-enzymic antioxidants is discussed.

Up-regulation of antioxidant and glyoxalase systems by exogenous glycinebetaine and proline in mung bean confer tolerance to cadmium stress

“…However, both of them maintained slightly higher CAT activity in comparison with seedlings treated with Cd alone. Our results are also supported by the results of Xu et al (2009) and Islam et al (2010). Similar effects of proline and betaine on CAT activity were also observed in response to various stresses (Demiral and Türkan 2004;Khedr et al 2003).…”

“…2a). Increase in GSH content in response to Cd stress were also reported in rice seedlings (Hu et al 2009;Xu et al 2009) and GSH metabolic genes coordinately respond to heavy metal stress (Xiang and Oliver 1998). The increase in GSSG content under Cd stress in the seedlings may partly be attributed to a decreased rate of GSH recycling or an increased rate of its degradation under the conditions of stress Hossain and Fujita 2010).…”

“…2a, c). An increase in GSH content due to proline pretreatment and lower lipid peroxidation has recently been reported (Xu et al 2009). Transgenic plants for higher proline and betaine biosynthesis also showed higher GSH, GSH/GSSG ratio and lower GSSG content as compared to wild-type under Cd medium and other stress conditions (Siripornadulsil et al 2002;Yang et al 2007).…”

“…Furthermore, betaine and proline provide protection against oxidative stress by maintaining redox homeostasis Hossain and Fujita 2010). Recently, it has been reported that betaine and proline alleviates Cd toxicity by detoxifying ROS and increasing antioxidant activity and GSH content in Solanum and tobacco BY-2 cells (Xu et al 2009;Islam et al 2010). To our knowledge, currently there is no information available on the possible beneficial effects of exogenous application of betaine and proline on MG detoxification system in plants grown under Cd stress.…”

Role of proline under changing environments

“…121 Proline induces the formation of phytochelatins which chelate with heavy metals like Cd thereby decreasing their toxicity. 122 Xu et al 123 reported that proline pre-treatment reduced the ROS level and also protected the plasma membrane of callus subjected to cadmium stress, thereby improving the cadmium tolerance resulting in regeneration of shoots in Solanum nigrum. Exogenous application of proline resulted in increase of its endogenous levels that antagonized the toxic effects of selenium by improving the growth of seedlings.…”