Protective role of exogenous phytohormones on redox status in pea seedlings under copper stress

The present work aims to provide insight on the role of phytohormone application in developing efficient practical defense strategies to improve plants tolerance under heavy metal contamination. For this purpose, pea (Pisum sativum L.) seeds were germinated in an aqueous solution of 200 mu M CuCl2 up to the 3rd day and then continued to germinate in the presence of distilled water (stress cessation) or were subjected to following combinations: Cu + 1 mu M IAA and Cu + 1 mu M GA(3) for 3 additional days. The results showed that copper excess induced oxidative stress in germinating seeds, which resulted in changes of the redox state of glutathione and cysteine, and proteomics revealed Cu-induced modifications of thiols (SH) and carbonyls (CO) (indicators of protein oxidation). However, application of IAA or GA(3) in the germination medium after 3 days of Cu exposure alleviated toxicity on seedlings, despite the persistence of Cu up to 6th day. This improving effect seems to be mediated by a cell Cu accumulation decrease and a protein reduced status recovery, since phytohormones modulate thioredoxin/ferredoxin systems in favor of protecting proteins against oxidation. In addition, an IAA and GA(3) protective effect was evidenced by a cellular homeostasis amelioration resulting from the balance conservation between the regeneration and consumption processes of glutathione and cysteine reduced forms. The exogenous effectors also induced modifications of profiles of SH and CO, suggesting changes in the regulation and expression of proteins that could be involved in defense mechanism against Cu stress

Efficiency of the green synthesized nanoparticles as new tools in cancer therapy: insights on plant-based bioengineered nanoparticles, biophysical properties, and anticancer roles

The aim of this work is to review the current knowledge on the efficiency of plant-based synthesized nanoparticles in medical field, particularly in the prevention, diagnosis, and therapy of cancer. For this, we examine the advantages of nanotechnological tools. Besides, a particular attention was given to understand the mechanism by which plant-based bioengineered nanoparticles can interact with components of cancerous cells. Green biosynthesized nanoparticles seem to be novel tool for prognostic biomarkers for cancer diagnosis and drug delivery in tumor cells. They can act either by leading to the damage of tumor cells, or by the protection of healthy cells, via mechanisms involving the specific properties of nanoparticles themselves and the antioxidative and antitumor properties found in plants. However, special attention should be given to the choice of plant species, extracts, and the toxic dose of some phytocompounds during the biosynthesis process. An increase in metal or trace element release from metal and metal oxide biosynthesized nanoparticles can lead to greater oxidative stress, which is associated with higher risk of cancer. Hence, plant-based nanosystems should be more developed to increase their specific targeting of the cancerous cells, in order to preserve the healthy ones

Alleviation of copper toxicity in germinating pea seeds by IAA, GA3, Ca and citric acid

The ameliorating effects of four exogenous effectors were investigated in germinating pea seeds exposed to copper excess. The results showed that the application of IAA, GA3, Ca or citric acid alleviated Cu-induced inhibition of growth and simultaneously reduced the oxidative stress injury, particularly contents of hydrogen peroxide, malondialdehyde and carbonyl groups. The improving effects can probably be mediated by the decreases in lipoperoxidation and protein oxidation as evidenced by changes in antioxidant enzyme activities. In addition, the efficiency of this recovery was compared within two types of treatments. Obtained results demonstrated that the stress abruption by the addition of effectors after three days of Cu application (treatment of type II) seems to be more effective than the simultaneous application of ‘Cu + effectors’ at the beginning of germination (treatment of type I). Data could provide some clues to physiological and biochemical mechanisms of the response of germinating seeds to the addition of chemicals under heavy metal stress

Redox biology response in germinating Phaseolus vulgaris seeds exposed to copper: Evidence for differential redox buffering in seedlings and cotyledon.

In agriculture, heavy metal contamination of soil interferes with processes associated with plant growth, development and productivity. Here, we describe oxidative and redox changes, and deleterious injury within cotyledons and seedlings caused by exposure of germinating (Phaseolus vulgaris L. var. soisson nain hâtif) seeds to copper (Cu). Cu induced a marked delay in seedling growth, and was associated with biochemical disturbances in terms of intracellular oxidative status, redox regulation and energy metabolism. In response to these alterations, modulation of activities of antioxidant proteins (thioredoxin and glutathione reductase, peroxiredoxin) occurred, thus preventing oxidative damage. In addition, oxidative modification of proteins was detected in both cotyledons and seedlings by one- and two-dimensional electrophoresis. These modified proteins may play roles in redox buffering. The changes in activities of redox proteins underline their fundamental roles in controlling redox homeostasis. However, observed differential redox responses in cotyledon and seedling tissues showed a major capacity of the seedlings' redox systems to protect the reduced status of protein thiols, thus suggesting quantitatively greater antioxidant protection of proteins in seedlings compared to cotyledon. To our knowledge, this is the first comprehensive redox biology investigation of the effect of Cu on seed germination

Effects of copper on reserve mobilization in embryo of Phaseolus vulgaris L.

The present research reports a biochemical and micro-submicroscopic analysis of copper effect on reserves mobilization during germination of Phaseolus vulgaris L. var. soisson nain hatif seeds. Dry embryonic cells are rich in protein bodies and little starch grains. In Cu-treated embryos copper inhibited 50% of albumin and globulin mobilization after 72 h imbibition. The severe alterations in treated embryo cells, observed by electron microscope, were probably the cause of the inability to utilize the amino acids freed by protein mobilization and so possibly the cause of the inhibition of P. vulgaris embryonic axes elongation

Activities of NAD(P)H oxidases and redox ratios of coenzymes in the seedlings (3 days-old) and the cotyledons (9 days-old) of germinated bean seeds in the presence of H₂O (CTR) or 200 μM Cu.

<p>Activities of NAD(P)H oxidases and redox ratios of coenzymes in the seedlings (3 days-old) and the cotyledons (9 days-old) of germinated bean seeds in the presence of H₂O (CTR) or 200 μM Cu.</p

Time courses of (A, B) germination rate and (C, D, E, F) seedling length in bean seeds in the absence (CTR) and in the presence of CuCl₂ (concentrations 20, 50, 100, 200, 500 μM).

<p>Letters indicate significant differences compared with the respective control sample (a: p < 0.05, b: p < 0.01 and c: p < 0.001).</p

Representative images of 1DE gels of proteins (100 μg) in cotyledons of bean seeds germinated for 3 days in the presence of (A) distilled water (CTR) or (B) 200 μM Cu.

<p>Gels were stained with Coomassie G-250 (scanned with GS-800 calibrated densitometer) and with FTSC labeling (scanned with Typhoon 9400 scanner). Total optical densities for each lane obtained from FTSC staining were normalized with those from Coomassie G-250 staining of the same gel. (C, D) Levels of proteins containing carbonyl groups. Values shown are (C) means of 4 biological replicates (±SD) numbered from 1 to 4, and (D) means of 4 technical replicates (±SD). Each measurement was performed in an extract obtained from several cotyledons. Analyses were performed using ANOVA, student’s T test; ***p<0.001.</p

Representative images of 1DE gels of proteins (150 μg) in cotyledons of bean seeds germinated for 9 days in the presence of (A) distilled water (CTR) or (B) 200 μM Cu. Gels were stained with Coomassie G-250 (scanned with GS-800 calibrated densitometer) and with IAF labeling (scanned with Typhoon 9400 scanner).

<p>Total optical densities for each lane obtained from IAF staining were normalized with those from Coomassie G-250 staining of the same gel. (C, D) Levels of proteins containing thiol groups. Values shown are (C) means of 4 biological replicates (±SD) numbered from 1 to 4, and (D) means of 4 technical replicates (±SD). Each measurement was performed in an extract obtained from several cotyledons. Analyses were performed using ANOVA, student’s T test; **p<0.01, ***p<0.001.</p

Proteins containing carbonyl groups (FTSC labeling) in the seedlings (3 days-old) (a) and the cotyledons (9 days-old) (b) of germinated bean seeds in the presence of H₂O (CTR) or 200 μM Cu.

<p>Proteins containing carbonyl groups (FTSC labeling) in the seedlings (3 days-old) (a) and the cotyledons (9 days-old) (b) of germinated bean seeds in the presence of H₂O (CTR) or 200 μM Cu.</p