Daniele Del Buono

A comparative study on the interference of two herbicides in wheat and italian ryegrass and on their antioxidant activities and detoxification rates.

A study was carried out to compare the effects of treating wheat (Triticum aestivum) and Italian ryegrass (Lolium multiflorum) with atrazine and fluorodifen. The herbicides interfered with photosynthesis and dark respiration, depending on the species. Atrazine decreased photosynthesis in both species and dark respiration in wheat, while fluorodifen caused decrements of photosynthetic activity of wheat. Antioxidant enzymes, such as ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), and glutathione reductase (GR), were generally more active in untreated and treated wheat with respect to Italian ryegrass, which explains why oxidative damage, expressed as malondialdehyde (MDA) content, was only found in ryegrass. Investigations on the activity of herbicide-detoxifying enzyme, glutathione S-transferase (GST), and on the accumulation and persistence of the herbicides in the plants showed higher detoxification rates in wheat than in the grass.

Copper accumulation in vineyard soils: Rhizosphere processes and agronomic practices to limit its toxicity.

Viticulture represents an important agricultural practice in many countries worldwide. Yet, the continuous use of fungicides has caused copper (Cu) accumulation in soils, which represent a major environmental and toxicological concern. Despite being an important micronutrient, Cu can be a potential toxicant at high concentrations since it may cause morphological, anatomical and physiological changes in plants, decreasing both food productivity and quality. Rhizosphere processes can, however, actively control the uptake and translocation of Cu in plants. In particular, root exudates affecting the chemical, physical and biological characteristics of the rhizosphere, might reduce the availability of Cu in the soil and hence its absorption. In addition, this review will aim at discussing the advantages and disadvantages of agronomic practices, such as liming, the use of pesticides, the application of organic matter, biochar and coal fly ashes, the inoculation with bacteria and/or mycorrhizal fungi and the intercropping, in alleviating Cu toxicity symptoms.

Glutathione S-transferases of italian ryegrass (Lolium multiflorum): activity toward some chemicals, safener modulation and persistence of atrazine and fluorodifen in the shoots.

Many varieties of Italian ryegrass (Lolium multiflorum) show resistance to herbicides; while this ability was frequently attributed to alterations in the target sites of the herbicides action of the plant or to an efficient oxidative metabolism, little attention has been paid to glutathione S-transferases (GSTs), which are a family of detoxifying enzymes involved in the inactivation of many toxic compounds. To investigate the role of GSTs, seedlings of Italian ryegrass were treated with four herbicides (atrazine, fenoxaprop-ethyl, fluorodifen, metolachlor) and a safener (fenchlorazol-ethyl). All the treatments were well tolerated by the plant, with very low decreases in terms of fresh weight and length of shoots. Regarding GST activity, the chemicals generally determined significant increases in the above enzyme activity toward the model-substrate CDNB. Therefore, the herbicides most GST inducing and the safener were tested themselves as enzyme substrates: constitutive GST activities toward atrazine, fluorodifen and fenchlorazol-ethyl were found, and, in addition, these activities were significantly induced by the safener. Following these results, a HPLC procedure was standardized in order to investigate the persistence of atrazine and fluorodifen in the seedlings of Italian ryegrass and the effect on this of the safener. It was found that the residual amounts of the two herbicides in the shoots were significantly reduced following the safener treatments.

Iron deficiency in barley plants: phytosiderophore release, iron translocation, and DNA methylation

All living organisms require iron (Fe) to carry out many crucial metabolic pathways. Despite its high concentrations in the geosphere, Fe bio-availability to plant roots can be very scarce. To cope with Fe shortage, plants can activate different strategies. For these reasons, we investigated Fe deficient Hordeum vulgare L. plants by monitoring growth, phytosiderophores (PS) release, iron content, and translocation, and DNA methylation, with respect to Fe sufficient ones. Reductions of plant growth, roots to shoots Fe translocation, and increases in PS release were found. Experiments on DNA methylation highlighted significant differences between fully and hemy-methylated sequences in Fe deficient plants, with respect to Fe sufficient plants. Eleven DNA bands differently methylated were found in starved plants. Of these, five sequences showed significant alignment to barley genes encoding for a glucosyltransferase, a putative acyl carrier protein, a peroxidase, a β-glucosidase and a transcription factor containing a Homeodomin. A resupply experiment was carried out on starved barley re-fed at 13 days after sowing (DAS), and it showed that plants did not recover after Fe addition. In fact, Fe absorption and root to shoot translocation capacities were impaired. In addition, resupplied barley showed DNA methylation/demethylation patterns very similar to that of barley grown in Fe deprivation. This last finding is very encouraging because it indicates as these variations/modifications could be transmitted to progenies.

Italian ryegrass for the phytoremediation of solutions polluted with terbuthylazine

The phytoextraction capacity of Italian ryegrass (Lolium multiflorum L.) to remove terbuthylazine (TBA) from aqueous solution has been assessed using a plant-based biotest (RHIZOtest). Three TBA concentrations (0.5, 1.0 and 2.0 mg L(-1)) were chosen to evaluate the tolerance capacity of the ryegrass. Even though the treatments negatively affected plants, they were able to remove up to 30-40% of TBA. In addition, some enzymatic activities involved in the response to TBA-induced stress were determined. Glutathione S-transferase (GST) has been activated with a TBA-dose dependent trend; ascorbate peroxidase (APX) activities have been induced within the first hours after the treatments, followed by decreases or disappearance in plants exposed to two higher dosages. In conclusion, this case-study highlights that the combination of ryegrass and RHIZOtest resulted to be effective in the remediation of aqueous solutions polluted by TBA.

Nitrate removal from polluted water by using a vegetated floating system

Nitrate (NO3(-)) water pollution is one of the most prevailing and relevant ecological issues. For instance, the wide presence of this pollutant in the environment is dramatically altering the quality of superficial and underground waters. Therefore, we set up a floating bed vegetated with a terrestrial herbaceous species (Italian ryegrass) with the aim to remediate hydroponic solutions polluted with NO3(-). The floating bed allowed the plants to grow and achieve an adequate development. Ryegrass was not affected by the treatments. On the contrary, plant biomass production and total nitrogen content (N-K) increased proportionally to the amount of NO3(-) applied. Regarding to the water cleaning experiments, the vegetated floating beds permitted to remove almost completely all the NO3(-) added from the hydroponic solutions with an initial concentration of 50, 100 and 150 mg L(-1). Furthermore, the calculation of the bioconcentration factor (BCF) indicated this species as successfully applicable for the remediation of solutions polluted by NO3(-). In conclusion, the results highlight that the combination of ryegrass and the floating bed system resulted to be effective in the remediation of aqueous solutions polluted by NO3(-).

Triosephosphate Isomerases in Italian Ryegrass (Lolium multiflorum): Characterization and Susceptibility to Herbicides

The effect of treatments with four herbicides and a safener on the activity of triosephosphate isomerase (TPI) extracted from shoots of Italian ryegrass was investigated. It was found that atrazine and fluorodifen, herbicides which interfere with photosynthesis, caused a decrease in measured enzyme activity. In addition, the in vitro effect of oxidized glutathione (GSSG), a compound produced in situations of oxidative stress, on TPI activity was investigated. It was shown that GSSG was a strong inhibitor of enzyme activity, at low concentrations in a dose-time-dependent manner. The enzyme extracts were submitted to chromatographic purifications and to two-dimensional electrophoresis. Some spots had molecular masses ranging between 20 and 30 kDa and were characterized and identified by LC-ESI-MS/MS as TPIs. The mass spectrometry also made it possible to identify the presence of cysteine residues that could be subjected to S-glutathionylation, which regulate the enzyme activity.

Utilization of Olive Husks as Plant Growing Substrates: Phytotoxicity and Plant Biochemical Responses

The substitution for peat in growing substrates used in plant nurseries with organic materials is gaining much attention due to environmental and economic advantages. In the present research, thirteen substrates were obtained by using different doses of two types of composted or noncomposted olive-mill husks and their toxicity was assessed by a seed germination bioassay using Lepidium sativum L and compared with a conventional substrate used as a control. Based on these results, six substrates were selected and their effect on Festuca and Italian ryegrass was evaluated and data compared with the same control. In particular, length of shoots and roots, fresh weight, and the activity of glutathione S-transferase (GST), glutathione peroxidase (GPx) and triosephosphate isomerase (TPI), were determined. Generally, the substrates did not cause lethal symptoms of stress, and it was ascertained that GST were responsive to phenols content, GPx to copper and nickel, and TPI to salinity. The results show the importance of composting in reducing phytotoxicity as evidenced by significant differences in GI and enzyme activities. Moreover the adoption of agricultural soil as a constituent of growing substrates is beneficial in contrasting the phytotoxic effects due to the presence of compounds contained in the soluble organic matter fraction, such as phenols.

Use of two grasses for the phytoremediation of aqueous solutions polluted with terbuthylazine

ABSTRACT The capacity of two grasses, tall fescue (Festuca arundinacea) and orchardgrass (Dactylis glomerata), to remove terbuthylazine (TBA) from polluted solutions has been assessed in hydroponic cultures. Different TBA concentrations (0.06, 0.31, 0.62, and 1.24 mg/L) were chosen to test the capacity of the two grasses to resist the chemical. Aerial biomass, effective concentrations (to cause reductions of 10, 50, and 90% of plant aerial biomass) and chlorophylls contents of orchardgrass were found to be more affected. Tall fescue was found to be more capable of removing the TBA from the growth media. Furthermore, enzymes involved both in the herbicide detoxification and in the response to herbicide-induced oxidative stress were investigated. Glutathione S-transferase (GST, EC. 2.5.1.18) and ascorbate peroxidase (APX, EC. 1.11.1.11) of tall fescue were found to be unaffected by the chemical. GST and APX levels of orchardgrass were decreased by the treatment. These negative modulations exerted by the TBA on the enzyme of orchardgrass explained its lower capacity to cope with the negative effects of the TBA.

Glutathione peroxidases in Lolium multiflorum and Festuca arundinacea: Activity, susceptibility to herbicides and characteristics.

To evidence a possible mechanism of defense toward oxidative stress induced by herbicides in plants, an investigation was carried on the activity of glutathione peroxidase (GPX) in Italian ryegrass (Lolium multiflorum) and in Festuca (Festuca arundinacea) in response to atrazine (6-chloro-N-ethyl-N′-isopropyl-1,3,5-triazine-2,4-diamine) and fluorodifen (4-nitrophenyl α,α,α-trifluoro-2-nitro-p-tolyl ether). In general, the herbicide treatments significantly induced GPX activity in the shoots of Italian ryegrass, whereas inhibited it in Festuca. These opposite behaviors are examined, taking into account the accumulation and persistence of the two herbicides in the plants, and they are discussed in terms of GPX counteraction to oxidative stress in the first case, and of a lower detoxification rate unable to prevent a deleterious effect on the GPX activity in the second case. Further information on the properties of Italian ryegrass and Festuca GPX were achieved by purification and isolation of the enzymes, performed by protein liquid chromatography and by electrophoretic analyses. GPX of both the plants were found to be heterodimer with multiple function in showing also glutathione S-transferase (GST) activity.