Acquired tolerance of tomato (Lycopersicon esculentum cv. Micro‐Tom) plants to cadmium‐induced stress

Abstract

The effects of varying concentrations of cadmium (Cd) on the development of Lycopersicon esculentum cv. Micro-Tom (MT) plants were investigated after 40 days (vegetative growth) and 95 days (fruit production), corresponding to 20 days and 75 days of exposure to CdCl 2 , respectively. Inhibition of growth was clearly observed in the leaves after 20 days and was greater after 75 days of growth in 1 mM CdCl 2 , whereas the fruits exhibited reduced growth following the exposure to a concentration as low as 0.1 mM CdCl 2 . Cd was shown to accumulate in the roots after 75 days of growth but was mainly translocated to the upper parts of the plants accumulating to high concentrations in the fruits. Lipid peroxidation was more pronounced in the roots even at 0.05 mM CdCl 2 after 75 days, whereas in leaves, there was a major increase after 20 days of exposure to 1 mM CdCl 2 , but the fruit only exhibited a slight significant increase in lipid peroxidation in plants subjected to 1 mM CdCl 2 when compared with the control. Oxidative stress was also investigated by the analysis of four key antioxidant enzymes, which exhibited changes in response to the increasing concentrations of Cd tested. Catalase (EC 1.11.1.6) activity was shown to increase after 75 days of Cd treatment, but the major increases were observed at 0.1 and 0.2 mM CdCl 2 , whereas guaiacol peroxidase (EC 1.11.1.7) did not vary significantly from the control in leaves and roots apart from specific changes at 0.5 and 1 mM CdCl 2 . The other two enzymes tested, glutathione reductase (EC 1.6.4.2) and superoxide dismutase (SOD, EC 1.15.1.1), did not exhibit any significant changes in activity, apart from a slight decrease in SOD activity at concentrations above 0.2 mM CdCl 2 . However, the most striking results were obtained when an extra treatment was used in which a set of plants was subjected to a stepwise increase in CdCl 2 from 0.05 to 1 mM, leading to tolerance of the Cd applied even at the final highest concentration of 1 mM. This apparent adaptation to the toxic effect of Cd was confirmed by biomass values being similar to the control, indicating a tolerance to Cd acquired by the MT plants.

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

“…3d). Decrease in GR activity due to Cd stress has been previously reported (Smeets et al 2008;Gratao et al 2008;Nouairi et al 2009). Exogenous application of proline or betaine kept this activity significantly higher under Cd stress which is accompanied by lower GSSG content, indicates proline and betaine play significant roles in efficient recycling of GSSG.…”

“…3e & f). Increased GPX and GST activity due to Cd stress were also reported in tomato (Gratao et al 2008), in rice seedlings (Hu et al 2009), in Arabidopsis (Semane et al 2007;Smeets et al 2008), in barley root tips (Haluskova et al 2009) and in Brassica napus (Nouairi et al 2009). In the present investigation, the increases of GST and GPX were not high enough to protect cells from Cd-induced oxidative damage.…”

“…Cd is a non-redox-active metal but it does elevate lipid peroxidation, contributing to a process of oxidative damage (Gratao et al 2008). Cd stress has been shown to cause an abrupt increase in the amount of MDA in leaves of different crops (Hsu and Kao 2007a, b;Wang et al 2008;Hu et al 2009;Nouairi et al 2009;Chao et al 2010) and in most of the cases the increase in H 2 O 2 content was correlated with a higher MDA level (Hsu and Kao 2007b;Hu et al 2009;Islam et al 2010;Wang et al 2008).…”

Simple procedure for nutrient analysis of coffee plant with energy dispersive X-ray fluorescence spectrometry (EDXRF)

“…XRF has been successfully applied in studies on the elemental composition of plants (Chuparina and Gunicheva, 2003;Marguí et al, 2009), soil contamination (Orescanin et al, 2003;Aslan et al, 2004;Marguí et al, 2005;Necemer et al, 2008) and agriculture (Noda et al, 2006;Oliveira et al, 2006;Gratão et al, 2008;Maity et al, 2010), which most of them applied pressed powder pellet to perform EDXRF analysis.…”

Effects of heavy metals toxicity on the biochemical response in tomato plants grown in contaminated silt-soil

“…Consideration of the level of uptake, translocation, and accumulation of toxic metals in different plant parts is of significance, as it has been suggested that plants might react as the first line of defense against toxicity by reducing metal concentration in active organs or cells through selective exclusion during uptake, excretion, or retention in the roots (Wu et al 2005). Metal toxicity causes interference with physiological functioning of plants, such as deleterious effects on the biosynthesis of chlorophylls (Qin, 1994;Hattab et al 2009), inhibition of growth in plants grown in metals-contaminated soil (Hattab et al 2009) (Gratao et al 2008;Nayek et al 2010). Metal stress response causes altered levels of plant protective enzymes, including peroxidase, catalase and ascorbate peroxidase (Cheng, 2003;Israr et al 2011), and accumulation of free proline (Cheng, 2003).…”