Metal Tolerance, Accumulation and Translocation in Poplar and Willow Clones Treated with Cadmium in Hydroponics

To evaluate the phytoremediation capability of some poplar and willow clones a hydroponic screening for cadmium tolerance, accumulation and translocation was performed. Rooted cuttings were exposed for 3 weeks to 50 μM cadmium sulphate in a growth chamber and morpho-physiological parameters and cadmium content distribution in various parts of the plant were evaluated. Total leaf area and root characteristics in clones and species were affected by cadmium treatment in different ways. Poplar clones showed a remarkable variability whereas willow clones were observed to be more homogeneous in cadmium accumulation and distribution. This behaviour was further confirmed by the calculation of the bio-concentration factor (BCF) and the translocation factor (Tf). Mean values of all the clones of the two Salicaceae species showed that willows had a far greater ability to tolerate cadmium than poplars, as indicated by the tolerance index (Ti), calculated on the dry weight of roots and shoots of plants. As far as the mean values of Tf was concerned, the capacity of willows to translocate was double that of poplars. On the contrary, the mean values of total BCF in poplar clones was far higher with respect to those in willows. The implications of these results in the selection of Salicaceae clones for phytoremediation purposes were discussed.     

Metschnikowia pulcherrima strain MACH1 outcompetes Botrytis cinerea, Alternaria alternata and Penicillium expansum in apples through iron depletion

A new strain of Metschnikowia pulcherrima (MACH1) was studied for its efficacy as a biocontrol agent against Botrytis cinerea, Penicillium expansum and Alternaria alternata on apples stored for 8 months at 1 °C. The results of two semi-commercial trials demonstrated the efficacy of the biocontrol strain MACH1. In order to understand the mechanism of action involved, the yeast strain was investigated for its competitive ability for iron against postharvest pathogens of apple. M. pulcherrima strain MACH1 was cultivated on PDA with different concentrations of iron (supplemented as FeCl₃) against A. alternata and B. cinerea. The yeast strain MACH1 produced a wider pigmented inhibition zone against both pathogens in low iron amendments while less inhibition was measured with increased iron concentrations. At the coloured inhibition zone, B. cinerea and A. alternata conidia did not germinate and mycelial degeneration was observed. In addition, a high reduction in infection by both pathogens was recorded in apples treated with M. pulcherrima strain MACH1 supplemented with low iron amendments compared to higher iron concentrations. The same experiments were carried out in vivo and in vitro against P. expansum. M. pulcherrima strain MACH1 amended with low iron concentration (5 μg mL⁻¹ FeCl₃), showing modest lesion diameter reduction and no effect on P. expansum under increased iron and without iron amendments. This study illustrated that iron depletion by the yeast strain MACH1 under low iron conditions could reduce the growth of some postharvest pathogens in vitro and in vivo. Although, iron depletion seems to be a primary mode of action against the postharvest pathogens studied, other mechanisms of action cannot be excluded in the biocontrol employed by M. pulcherrima strain MACH1.     

A recombinant flagellin fragment,which includes the epitopes flg22 and flgII-28, provides a useful tool to study flagellin-triggered immunity

Plants and animals independently evolved the ability to recognize flagellin (also called FliC), the building block of the bacterial flagellum, as part of their innate immune response. While animals recognize a relatively large region of FliC, most plants recognize one or two short epitopes of FliC: flg22 and flgII-28. However, since most research in plants has focused on flg22 and flgII-28 and not the actual FliC protein, the importance of any FliC region beyond the two epitopes in plant immunity is poorly understood. Here we report cloning, overexpression, and purification of a Pseudomonas syringae FliC fragment from amino acid 1 to 143, which includes both FliC epitopes and the adjacent alpha helices. Exposing Arabidopsis thaliana leaves to FliC_1–143 did not reveal any additional FliC recognition capabilities beyond flg22. However, while the kiwifruit species Actinidia arguta did not respond to either flg22 or flgII-28, treatment of A. arguta leaves with FliC_1–143 triggered a significant reactive oxygen response, indicating recognition. This result suggests that in some plant species, recognition of FliC requires regions of FliC beyond the two well-known epitopes and that FliC_1–143 represents a useful tool in the study of plant immunity.     

Natural antimicrobials in spray-dried microparticles based on cellulose derivatives as potential eco-compatible agrochemicals

Journal of Plant Diseases and Protection - It has been demonstrated that some aromatic substances synthesized by plants serve as plant defense mechanisms. However, natural extracts are difficult to...     

Cytochrome b gene structure and consequences for resistance to Qo inhibitor fungicides in plant pathogens

The cytochrome b (cyt b) gene structure was characterized for different agronomically important plant pathogens, such as Puccinia recondita f sp tritici (Erikss) CO Johnston, P graminis f sp tritici Erikss and Hennings, P striiformis f sp tritici Erikss, P coronata f sp avenae P Syd & Syd, P hordei GH Otth, P recondita f sp secalis Roberge, P sorghi Schwein, P horiana Henn, Uromyces appendiculatus (Pers) Unger, Phakopsora pachyrhizi Syd & P Syd, Hemileia vastatrix Berk & Broome, Alternaria solani Sorauer, A alternata (Fr) Keissl and Plasmopara viticola (Berk & Curt) Berlese & de Toni. The sequenced fragment included the two hot spot regions in which mutations conferring resistance to QoI fungicides may occur. The cyt b gene structure of these pathogens was compared with that of other species from public databases, including the strobilurin-producing fungus Mycena galopoda (Pers) P Kumm, Saccharomyces cerevisiae Meyer ex Hansen, Venturia inaequalis (Cooke) Winter and Mycosphaerella fijiensis Morelet. In all rust species, as well as in A solani, resistance to QoI fungicides caused by the mutation G143A has never been reported. A type I intron was observed directly after the codon for glycine at position 143 in these species. This intron was absent in pathogens such as A alternata, Blumeria graminis (DC) Speer, Pyricularia grisea Sacc, Mycosphaerella graminicola (Fuckel) J Schr?t, M fijiensis, V inaequalis and P viticola, in which resistance to QoI fungicides has occurred and the glycine is replaced by alanine at position 143 in the resistant genotype. The present authors predict that a nucleotide substitution in codon 143 would prevent splicing of the intron, leading to a deficient cytochrome b, which is lethal. As a consequence, the evolution of resistance to QoI fungicides based on G143A is not likely to evolve in pathogens carrying an intron directly after this codon.     

Induction of Systemic Acquired Resistance in Pepper Plants by Acibenzolar-S-methyl against Bacterial Spot Disease

The ability of acibenzolar-S-methyl to induce resistance in pepper plants against Xanthomonas campestris pv. vesicatoria was investigated in both growth chamber and open field conditions. Growth chamber experiments showed that acibenzolar-S-methyl (300M) treatment protects pepper plants systemically and locally against X. campestris pv. vesicatoria. Evidence for this was a reduction in the number and diameter of bacterial spots and bacterial growth in planta. Systemic protection was also exerted by the acibenzolar-S-methyl acid derivative, CGA 210007, which may be produced by hydrolysis in the plant. The efficacy of acibenzolar-S-methyl was also found in open field conditions, where both leaves and fruit were protected from the disease. The highest efficacy (about 67%) was obtained by spraying the plants 6–7 times every 8–12 days with a mixture of acibenzolar-S-methyl and copper hydroxide (2.5 + 40ghl^–1 active ingredient). Persistence and translocation data obtained from the growth chamber experiments revealed a persistence of acibenzolar-S-methyl lasting five days after treatment with rapid translocation and negligible levels of acid derivative formation. Since the protection exerted by acibenzolar-S-methyl against bacterial spot disease was observed when the inducer was completely degraded, it would appear to be due to SAR activation.     

Evaluation of serum enzyme activities as predictors of passive transfer status in lambs

OBJECTIVE: To determine the associations between serum IgG concentration and serum activities of gamma-glutamyltransferase (GGT), alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and pseudocholinesterase for the potential use of these serum enzymes as predictors of passive transfer status in neonatal lambs. DESIGN: Prospective observational study. ANIMALS: 47 Sardinian lambs from birth to 2 days old. PROCEDURE: Serum enzyme activities were measured by use of commercially available kits and a clinical biochemical analyzer. Serum IgG concentration was determined by single radial immunodiffusion. Associations between serum IgG concentration and the activity of each serum enzyme were established by use of regression analysis. RESULTS: A significant correlation was detected between serum IgG concentration and serum GGT activity in 1- and 2-day-old lambs. Minimal correlations were detected between serum IgG concentration and serum alkaline phosphatase activity in 1-day-old lambs and serum pseudocholinesterase activity in 1- and 2-day-old lambs. No significant associations were detected between serum IgG concentration and serum activities of aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase. A multiple linear regression model was accurate for the estimation of the natural logarithm of serum IgG concentration as a function of the natural logarithm of serum GGT activity and of the age of lambs at the time of sampling (adjusted R2 = 0.89). This model was then used to calculate the serum GGT activity equivalent to various serum IgG concentrations for 1- and 2-day-old lambs. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that passive transfer status in neonatal lambs can be successfully predicted by measurement of serum GGT activity but not by measurement of the other enzymes tested.     

Laparoscopic ovariectomy in dogs: comparison between laparoendoscopic single-site and three-portal access

This study was conducted to evaluate the feasibility and therapeutic safety of laparoendoscopic single-site ovariectomy (LESS-OVE) and 3-portal laparoscopic ovariectomy (Lap-OVE) in dogs. Ten female mixed breed dogs were included in the study. Dogs were divided into group 1 (LESS-OVE; n = 5) and group 2 (Lap-OVE; n = 5). All procedures were performed by laparoscopic-skilled surgeons, and the anesthetic protocol was the same for all patients. In both groups, the ovarian vascular pedicle and ligaments were transected using a bipolar vessel sealer/divider device. The mean total surgical time was slightly longer in LESS-OVE (36.6 ± 3.5 min) than Lap-OVE (32.0 ± 3.0 min); however, the differences were not significant. Perioperative complications were not reported in any group. Both laparoscopic techniques were shown to be equally feasible and safe for patients. However, surgeons found LESS-OVE to require more skill than Lap-OVE. Therefore, additional studies should be conducted to evaluate this novel approach in clinical veterinary practice, and a proper laparoscopic training program for veterinary surgeons should be developed.