Variations in growth, survival and carbon isotope composition (delta(13)C) among Pinus pinaster populations of different geographic origins

To evaluate differences in growth and adaptability of maritime pine (Pinus pinaster Ait.), we studied growth, polycyclism, needle tissue carbon isotope composition (delta(13)C) as an estimate of water-use efficiency (WUE) and survival of seven populations at 10 years of age growing in a performance trial at a provenance test site in Escaroupim, Portugal. Six populations were from relatively high rainfall sites in Portugal and southwestern France (Atlantic group), and one population was from a more arid Mediterranean site in Spain. There were significant differences between some populations in total height, diameter at breast height, delta(13)C of bulk needle tissue, polycyclism and survival. A population from central Portugal (Leiria, on the Atlantic coast) was the tallest and had the lowest delta(13)C. Overall, the variation in delta(13)C was better explained by the mean minimum temperatures of the coldest month than by annual precipitation at the place of origin. Analyses of the relationships between delta(13)C and growth or survival revealed a distinct pattern for the Mediterranean population, with low delta(13)C (and WUE) associated with the lowest growth potential and reduced survival. There were significant negative correlations between delta(13)C and height or survival in the Atlantic group. Variation in polycyclism was correlated with annual precipitation at the place of origin. Some Atlantic populations maintained a high growth potential while experiencing moderate water stress. A detailed knowledge of the relationships between growth, survival and delta(13)C in contrasting environments will enhance our ability to select populations for forestry or conservation.     

Fusarium oxysporum f. sp. lycopersici races and their genetic discrimination by molecular markers in West Mediterranean region of Turkey

Fusarium oxysporum f. sp. lycopersici (FOL) races and F. oxysporum f. sp. radicis lycopersici (FORL), the causal agents of root rot and crown rot diseases, respectively, cause serious economic losses in tomato greenhouses where production is intensive in the West Mediterranean region of Turkey. The isolates were collected from West Mediterranean region of Turkey and were characterized by specific primers based on three races (r1, r2, r3), besides pathogenicity tests in in vivo conditions Additionally, a scheme was developed using newly tested ISSR and SRAP markers to a genotyping database and to determine the possible origin of these pathogens. The present study provided new information on these pathogens based on their races and their dominant existence in this region that has not been reported before. Genetic diversity detected in the same races of the pathogen may be associated with difficulties in controlling the pathogen and a possible resistance formation effort exerted by the pathogen to chemicals used in plant protection in tomato greenhouses. Molecular analyses indicated genetic diversity in pathogen isolates identified as r3, r2 and FORL, which may be associated with abiotic stress to which the pathogens were exposed.     

Simultaneous detection of six RNA plant viruses affecting tomato crops using a single digoxigenin-labelled polyprobe

A polyprobe for the simultaneous detection by non-isotopic molecular hybridisation has been developed to detect any of the following six viruses causing important economic losses in tomato crops: Tomato spotted wilt virus, Tomato mosaic virus, Pepino mosaic virus, Cucumber mosaic virus, Potato Y virus and Parietaria mottle virus. The polyprobe detected all six viruses with similar sensitivity to that obtained using individual riboprobes. In addition, we evaluated the possible use of the tissue-printing as a sample preparation technique applied to routine diagnosis of tomato plants with the polyprobe. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Differential effects of phytotoxic metabolites from <Emphasis Type="Italic">Alternaria tagetica</Emphasis> on <Emphasis Type="Italic">Tagetes erecta</Emphasis> cell cultures

Alternaria tagetica, a fungus that causes early blight in marigold (Tagetes erecta), produces two groups of phytotoxic metabolites: one hydrophilic and the other lipophilic that show phytotoxic activity when tested by the leaf-spot assay in T. erecta. We evaluated the cellular effects of the phytotoxic culture filtrate of A. tagetica and the hydrophilic and lipophilic fractions, then determined whether the filtrate or the fractions differentially induced pathogenesis-related mechanisms in the plant. The culture filtrate and the phytotoxic fractions had adverse effects on cell viability, fresh mass, and the number of cells, and induced ROS accumulation, lipid peroxidation and DNA damage on T. erecta cell suspension cultures, and these effects are related to pathogenic mechanisms attributed to phytotoxins. However, although exposure of marigold cells to the phytotoxic culture filtrate of A. tagetica triggered programmed cell death, the hydrophilic and the lipophilic phytotoxic fractions induced death that was more related to a toxic effect leading to necrosis. This study presents a complementary perspective in the search for the roles of metabolites, including phytotoxins, produced by phytopathogenic fungi during plant infection.     

Multivariate analysis of toxicological and environmental properties of soil nematicides

BACKGROUND: In intensive agriculture, the use of pesticides and soil fumigants is necessary to produce economically viable crops worldwide. However, this practice may involve undesirable effects on human health and the environment. In 1995, methyl bromide was restricted by the Montreal Protocol because of possible ozone depletion. The objective of this study was to compare intrinsic environmental and toxicological properties of 11 active substances with nematicidal properties, some of them recognized as methyl bromide alternatives. RESULTS: Four groups of active substances were discriminated by a series of principal component analyses (PCAs): (a) high toxicity to non-target fauna, humans and animals and medium persistence in the environment (cadusafos, ethoprophos and fenamiphos); (b) high toxicity to humans, animals and non-target fauna and high persistence (carbofuran and fosthiazate); (c) low toxicity to non-target fauna, humans and animals and low persistence (carbosulfan, benfuracarb and oxamyl); (d) low toxicity to humans, animals and non-target fauna and medium persistence in the environment (1,3-dichloropropene, chloropicrin and methyl bromide). CONCLUSION: Evaluating the multiple aspects of toxicological and environmental properties of active substances through PCA is proposed as a helpful tool for initially comparing the complex toxicological behaviour of active substances as plant protection products.     

Detection of citrus canker in citrus plants using laser induced fluorescence spectroscopy

Citrus canker is a serious disease caused by Xanthomonas citri subsp. citri bacteria, which infects citrus plants (Citrus spp.) leading to a large economic loss in citrus production worldwide. In Brazil citrus canker control is done by an official eradication campaign, therefore early detection of such disease is important to prevent greater economic losses. However, detection is difficult and so far it has been done by visual inspection of each tree. Suspicious leaves from citrus plants in the field are sent to the laboratory to confirm the infection by laboratory analysis, which is a time consuming. Our goal was to develop a new optical technique to detect and diagnose citrus canker in citrus plants with a portable field spectrometer unit. In this paper, we review two experiments on laser induced fluorescence spectroscopy (LIF) applied to detect citrus canker. We also present new data to show that the length of time a leaf has been detached is an important variable in our studies. Our results show that LIF has the potential to be applied to citrus plants.     

Cardiovascular effects of Hyptis fruticosa essential oil in rats

In non-anesthetized normotensive rats, Hyptis fruticosa essential oil (HFEO, 5, 10, 20 and 40 mg/kg; i.v.) induced hypotension associated with tachycardia. In intact and isolated rings of rat superior mesenteric artery (control), HFEO (1-1000 microg/ml, n=6, cumulatively) induced concentration-dependent relaxations of tonus induced by 10 microM phenylephrine (Phe) (pD(2)=2.6+/-0.27; E(max)=64+/-8.3%). In denuded endothelium pre-contracted rings with Phe or K(+)-depolarizing solution (80 mM), the concentration-response curves to HFEO were not shifted (pD(2)=2.3+/-0.25 and 2.3+/-0.28, respectively), but their maximal responses were significantly (P<0.05 vs control) increased (E(max)=122.3+/-18.2% and 92+/-3.6%, respectively). HFEO was also capable of antagonizing the concentration-response curves to CaCl(2) (3 microM-30 mM) in a dose-dependent manner.     

Antinociceptive effect and acute toxicity of the essential oil of Hyptis fruticosa in mice

The essential oil of the Hyptis fruticosa leaves was analyzed by GC/MS and evaluated for antinociceptive property as well as acute toxicity in mice. The essential oil, at doses of 100, 200, and 400 mg/kg (s.c.), produced significant inhibition of acetic acid-induced writhing, but did not manifest a significant effect in hot-plate test. There was no acute toxicity at doses up to 5 g/kg. Bicyclogermacrene, 1,8-cineole, alpha-pinene, and beta-caryophyllene were the major compounds detected in the essential oil.     

Linalool production from the leaves of Bursera aloexylon and its antimicrobial activity

The oil of the leaves of Bursera aloexylon was found to contain a high linalool level (96.7 %). The antimicrobial activity tests indicated that the oil was effective against Rhodococcus equi (0.60 mg/ml) and Staphylococcus epidermides (0.15 mg/ml).