Effect of mixed inoculations with Fusarium oxysporum f. sp. lycopersici and F. oxysporum f. sp. dianthi on the phenols content of tomato plants

Forms ofFusarium oxysporum specific on hosts other than tomato induce in this plant greater initial increases of the phenols content than the pathogenic f. sp.lycopersici. Mixed inoculations of f. sp.lycopersici and f. sp.dianthi are on the contrary no more effective in inducing the phenol accumulation 24 h after the infection than f. sp.lycopersici alone. This observation suggests that the pathogen can suppress the phenolic response that is typical of the incompatible combinations.Samenvatting Vormen vanFusarium oxysporum welke pathogeen zijn voor andere planten dan de tomaat induceren in deze plant aanvankelijk een grotere toename van het fenolgehalte dan de pathogene f. sp.lycopersici. Inoculaties met een gemengd inoculum van de f. sp.lycopersici en f. sp.dianthi hebben daarentegen geen groter effect op de toename van het fenolgehalte 24 uur na infectie dan de inoculaties met f. sp.lycopersici alleen. Verondersteld wordt dat het pathogeen de toename van het fenolgehalte, dat typerend is voor de incompatibele combinatie, kan onderdrukken.     

New polyphenol derivative in Ipomoea batatas tubers and its antioxidant activity

Four different polyphenolic compounds were isolated by chromatographic methods from methanolic and hydromethanolic extracts of Ipomoea batatas tuber flour. On the basis of UV, mass, and NMR analysis procedures, the structure of the isolated compounds were determined as 4,5-di-O-caffeoyldaucic acid (1), 4-O-caffeoylquinic acid (2), 3,5-di-O-caffeoylquinic acid (3), and 1,3-di-O-caffeoylquinic acid (4). To the best of our knowledge, this is the first report of isolation and characterization of compound 1. Then, we evaluated the antioxidant activity of daucic acid derivative by using DPPH and FRAP methods together with authentic antioxidant standards, l-ascorbic acid, tert-butyl-4-hydroxy toluene (BHT), and gallic acid. The activity of compound 1 in both methods was higher than that of all standards used at the same molar concentration.     

Diversity of Paenibacillus durus strains isolated from soil and different plant rhizospheres evaluated by ARDRA and gyrB-RFLP analysis

Strains belonging to Paenibacillus durus isolated from the rhizosphere of various grasses and from bulk soil were previously divided into five phenotypic groups (A1–A5) based on the fermentation pattern of six carbohydrates (A1: sorbitol (+), A2: dulcitol and tagatose (+), A3: starch and glycogen (+), A4: starch, glycogen and d-arabitol (+) and A5: negative for these carbohydrates). This study aimed to assess whether plant types select for specific P. durus phenotypic groups. For that purpose, polymerase chain reaction-restriction fragment length polymorphism analysis of part of genes encoding 16S rRNA (ARDRA) and DNA gyrase subunit B (gyrB-RFLP) were used to produce genetic fingerprints. ARDRA and gyrB-RFLP data were clustered together to generate a dendrogram and two main clusters were observed. Cluster I showed a predominance of strains isolated from wheat, maize and sugarcane rhizospheres. Strains isolated from maize were distributed among the five patterns of carbohydrate metabolism, while strains isolated from sugarcane showed to be predominantly able to metabolize starch and glycogen. Neither sorbitol- nor arabitol-metabolizing strains were found in cluster II, which consisted of strains isolated from soil and from all plant species used. Our results suggest that the plants influenced the diversity of P. durus in their rhizospheres.     

Airborne fungal succession in a rice field of Cuba

This study characterised the airborne mycobiota of a rice plantation in Bauta (Havana, Cuba), with a view to improving crop quality. Culturable airborne fungi were sampled between March 2007 and February 2008 using a volumetric method (SAS Super 100) with potato dextrose agar as culture medium. The total fungal count was 51,425 cfu/m³. The 39 filamentous genera identified included several major rice pathogens (Bipolaris, Curvularia, Alternaria, Pyricularia, Cercospora and Fusarium) as well as potentially mycotoxigenic species of Fusarium, Penicillium and Aspergillus. Analysis of the influence of weather-related factors on spore counts revealed that total counts and Penicillium counts correlated positively with daily relative humidity, mean temperature and dew point.     

Geminivirus C2 protein represses genes involved in sulphur assimilation and this effect can be counteracted by jasmonate treatment

Geminiviruses are plant viruses that infect a broad range of crops and cause extensive losses worldwide, having an important economic impact. C2, a multifunctional pathogenicity factor encoded by geminiviruses, has been recently shown to suppress the responses to jasmonates in the host plant, which might at least partially explain its well-established role in pathogenicity. Sulphur is one of the essential macro-elements for plant life, and is considered to have a role in plant defence, in a phenomenon named sulphur-induced resistance (SIR) or sulphur-enhanced defence (SED). In this work, we show that geminivirus C2 protein represses the expression of genes involved in the sulphur assimilation pathway in Arabidopsis, but, interestingly, this effect can be neutralized by exogenous jasmonate treatment. These preliminary results may raise the idea that geminiviruses might be affecting sulphur metabolism, and maybe counteracting SIR/SED, through the manipulation of the jasmonate signalling pathway, which would define a novel strategy in plant-virus interactions and may unveil SIR/SED as an important player in the plant defence against viruses.     

Learning by doing: a participatory methodology for systematization of experiments with agroforestry systems, with an example of its application

Participatory research methods have helped scientists to understand how farmers experiment and to seek partnerships with farmers in developing technologies with enhanced relevance and adoption. This paper reports on the development of a participatory methodology to systematize long-term experimentation with agroforestry systems carried out in a hotspot of biodiversity by non-governmental organizations and local farmers. A methodological guide for systematization and techniques used for Participatory Rural Appraisal formed the basis of our work. We propose an analytical framework that recognizes systems of reflexive and learning interactions, in order to make the learned lessons explicit. At the process level, the main lessons and recommendations are as follows. It is important to establish partnerships to conduct innovative and complex experimentation with agroforest. Participatory systematization allows us to improve the methodological aspects of design, implementation and management of on-farm participatory experimentation. It also serves to synthesize the main findings and to extract lessons from agroforestry systems experiments. It fosters the technical improvement of agroforestry systems. It creates possibilities for reflection on agroforestry systems by farmers, extensionists and researchers, as well as their learning with respect to management of such systems. The findings are placed in the context of current theory on participatory experimentation in agriculture. Extractive and interactive approaches help to produce rich insights of mutual interest through collaboration by identifying local, regional and global convergences, complementarities, and conflicts of interest; which affect the advance of new eco-friendly technologies, to both improve the livelihoods and to reverse biodiversity loss and environmental degradation.     

Disseminated mite infection with ocular involvement in a juvenile bald eagle (Haliaeetus leucocephalus)

A bald eagle (Haliaeetus leucocephalus) was found unable to fly and was admitted to The Raptor Center (TRC). Major clinical signs were thin body condition and a cardiac arrhythmia. Ten days after admission to TRC, ophthalmic examination revealed multiple, distinct serpiginous lesions of chorioretinal atrophy in the ocular fundus of the right eye (OD). The bird was euthanized because of clinical deterioration and poor prognosis. Mites of an undetermined species were found histologically in the retina, episcleral tissues, lungs, and liver at the postmortem examination. Disseminated mite infection should be considered in the differential diagnosis of serpiginous chorioretinal lesions in bald eagles (H. leucocephalus).     

Comparison of the key aroma compounds in organically grown, raw West-African peanuts (Arachis hypogaea) and in ground, pan-roasted meal produced thereof

Application of an aroma extract dilution analysis on an aroma distillate prepared from organically grown, raw West-African peanuts (Cameroon) revealed 36 odor-active areas in the flavor dilution (FD) factor range of 1 to 2048. The identification experiments, which were all performed by using the respective reference chemicals, revealed 2-isopropyl-3-methoxypyrazine (earthy, pea-like), 2-isobutyl-3-methoxypyrazine (bell pepper-like, earthy), and trans-4,5-epoxy-(E)-2-decenal (metallic) with the highest FD factors among the 36 aroma compounds identified. The two last mentioned odorants and another set of 22 further odorants were identified for the first time in raw peanuts. A comparative aroma extract dilution analysis applied on distillates prepared from either the raw peanuts or ground peanut meal roasted in a pan showed 52 odor-active areas in the FD factor range of 8 to 2048 in the roasted nut material. The identification experiments in combination with the FD factors revealed that among them, 2-acetyl-1-pyrroline and 4-hydroxy-2,5-dimethyl-3-(2H)-furanone showed the most significant contribution to the overall aroma, followed by 1-octen-3-one, 2-isopropyl-3-methoxypyrazine, (E, E)-2,4-decadienal, and trans-4,5-epoxy-(E)-2-decenal. As a further result, 20 aroma compounds were newly identified in roasted peanuts, such as 2-propionyl-1-pyrroline and 2-acetyltetrahydropyridine (both popcorn-like). In particular, 2-acetyl-1-pyrroline and 4-hydroxy-2,5-dimethyl-3(2 H)-furanone showed the most pronounced increase after roasting.