Transmission Efficiency of <Emphasis Type="Italic">Potato Leafroll Virus</Emphasis> by Four Potato Colonizing Aphid Species in Tunisian Potato Fields

This study investigated the transmission efficiency of Potato leafroll virus (PLRV) by four potato colonizing aphid species, Myzus persicae, Macrosiphum euphorbiae, Aphis gossypii and Aphis fabae, reported from leaves and yellow water trap. Physalis floridana was used as a test plant for virus transmission. DAS-ELISA was used for virus screening of samples as well as virus detection on the test plant after transmission experiment. A 2-h period was sufficient for the tested aphids to acquire PLRV virions. However, a difference in the transmission potential occurred according to the aphid species. The highest potential was recorded for M. persicae and M. euphorbiae, at 90 and 80%, respectively. For the first time, the study revealed the PLRV transmission efficiency of A. fabae, estimated at 50%. The lowest potential rate of 30% was recorded for A. gossypii. This study highlights the PLRV transmission capacities of four potato colonizing aphids suspected to play a key role in the spread of PLRV in potato seed production sites.     

Molecular endocrine changes of Gh/Igf1 axis in gilthead sea bream (<Emphasis Type="Italic">Sparus aurata</Emphasis> L.) exposed to different environmental salinities during larvae to post-larvae stages

The influence of acclimation of the euryhaline gilthead sea bream (Sparus aurata) larvae/post-larvae to brackish water on growth, energetic contents, and mRNA levels of selected hormones and growth-regulating hypothalamic neurohormones was assessed. Specimens from 49 days post-hatching were acclimated during 28 days to two different environmental salinities: 38 and 20 psu (as brackish water). Both groups were then transferred to 38 psu and acclimated for an additional week. Early juveniles were sampled after 28 days of acclimation to both salinities and one week after transfer to 38 psu. Pituitary adenylate cyclase-activating peptide (adcyap1; pacap), somatostatin-I (sst1), growth hormone (gh1), insulin-like growth factor-I (igf1), and prolactin (prl) mRNA expression were all studied by QPCR. Post-larvae acclimated to 20 psu showed better growth performance and body energetic content than post-larvae maintained at 38 psu. prl, adcyap1, and igf1 mRNA expression levels increased in 20-psu-acclimated post-larvae but decreased upon transfer to 38 psu. GH1 expression did not show significant changes under both experimental conditions. Our results suggested an enhanced general performance for post-larvae in brackish water, supported by the actions of adcyap1, igf1, and prl.     

Choanephora rot of floral tops of <Emphasis Type="Italic">Hyoscyamus muticus</Emphasis> caused by <Emphasis Type="Italic">Choanephora cucurbitarum</Emphasis>

Floral rot of Egyptian henbane (Hyoscyamus muticus L.) was found on potted plants in a greenhouse in Yamaguchi city, Japan, in the late summer of 2008 and 2009. The symptoms were identical to those of rots caused by Choanephora species. The pathogen was isolated and identified as C. cucurbitarum (Berkeley and Ravenel) Thaxter. This new disease was named Choanephora rot (Kougai-kabi-byo) of Egyptian henbane.     

Evaluation of Compost Maturity,Hydrophysical and Physicochemical Properties: Indicators for Use as a Component of Growing Media

The cocomposting of agricultural waste is a new management priority in Tunisia. In this study, four composts were evaluated by comparing the changes in measured hydrophysical and physicochemical properties and phytotoxicity. The organic wastes used were almond shell (AS), sesame bark (SB), olive husk (OH), and green and wood wastes (GW and WW, respectively). Composts CI and CII were composed of AS/SB and OH/SB, respectively, at a ratio of 75/25 (wet weight basis). CIII consisted of OH, SB and CAS (coarsely-ground almond shell used as a bulking agent) at a ratio of 55/25/20. Finally, CIV was composed of 25%SB+9%CAS+18%GW+48%WW. The composts studied were characterized by basic pH and an electric conductivity (EC) value ranging from 1.6 to 2.4 mS/cm. The organic matter contents (OM) and C/N ratios of composts ranged from 20 to 46% and from 10 to 21%, respectively. Based on hydrophysical analyses, composts CI, CIII and CIV, containing AS, were shown to have a porosity and a water content of 10-26% and 10-20%, respectively. The phytotoxicity of composts was studied on the basis of cress seed germination. Results revealed that differences in properties are mainly related to the nature of composted waste and that some of these composts are compatible for use as constituents in growing media for horticultural soilless cultures.     

Antioxidant and Antiproliferative Activity of <Emphasis Type="Italic">Diospyros lotus</Emphasis> L. Extract and Isolated Compounds

The object of the study was to determine the chemical composition of Diospyros lotus L. extract and their antioxidant and antiproliferative properties. Eight compounds were isolated from D. lotus and identified as gallic acid, methylgallate, ellagic acid, kaempferol, quercetin, myricetin, myricetin 3-O-β-glucuronide, and myricetin-3-O-α-rhamnoside. D. lotus extract tested in different in vitro systems (DPPH, ABTS, FRAP, and Fe²⁺ chelating activity assay) showed significant antioxidant activity. The potential antiproliferative properties of D. lotus extract and isolated compounds against nine human cancer cell lines such as COR-L23, CaCo-2, C32, ACHN, A375, A549, Huh-7D12, MCF-7, and LNCaP were investigated in vitro by SRB assay. D. lotus extract demonstrated the highest inhibitory activity against COR-L23 with an IC₅₀ value of 12.2 μg/ml. Among identified hydrolysable tannins, ellagic acid evidenced strong antiproliferative activity against both C32 and A375 cells with IC₅₀ values of 0.8 and 4.1 μg/ml, respectively. Interesting results were observed, also, with gallic acid that showed the highest cytotoxic activity against CaCo-2 (IC₅₀ 2.6 μg/ml). Overall, the results of this study suggest that D. lotus displays a good antioxidant activity and has antiproliferative effects. Both activities are related to identified phenolic compounds.     

Effects of commonly used disinfectants on bacterial load,hatchability and survival of Bluefin Sea bream (Sparidentex hasta) eggs

The efficacy of four chemical reagents, iodophor, formalin, hydrogen peroxide and bronopol as fish egg surface disinfectants were evaluated in bluefin sea bream (Sparidentex hasta). Fertilized eggs were counted and subjected to a static bath dip treatment in different concentrations of the above chemicals for 4 min before being incubated at 20 ± 0.5°C for 40 h. Treatment efficacy of the different disinfectants was evaluated by assessing the bactericidal activity, egg hatch percentage and survival of larvae up to 3 days post hatch. Results showed that iodophor at medium concentrations (75 and 100 ppm) was the best of all tested disinfectants in bacterial killing ability (12% reduction in the bacterial counts), egg hatching per cent (99.8% and 99.6% respectively) and larval survival up to 3 days post hatch (50.8% and 54.8% respectively). Formalin was the second best disinfectant at levels of 100 and 150 ppm. Hydrogen peroxide gave good results compared with the control while, bronopol showed discouraging results. In conclusion, iodophor appeared to be suitable for bluefin sea bream eggs disinfection with a 4 min exposure to 75–100 ppm when applied 14–16 h after egg fertilization.     

Antifungal activities of hyoscyamine and scopolamine against two major rice pathogens: <Emphasis Type="Italic">Magnaporthe oryzae</Emphasis> and <Emphasis Type="Italic">Rhizoctonia solani</Emphasis>

The antifungal activities of hyoscyamine and scopolamine, major alkaloids extracted from the desert plant Hyoscyamus muticus, against two rice pathogens, Magnaporthe oryzae and Rhizoctonia solani, were studied. The minimum inhibitory concentration of hyoscyamine that resulted in distinctive inhibition (MIC₅₀) was 1 μg/ml for both fungi. Exposure to hyoscyamine caused the leakage of electrolytes from the mycelia of both fungi. Hyoscyamine (>1 μg/ml) irreversibly delayed or inhibited conidial germination and appressorium formation in M. oryzae grown on polystyrene plates. Hyoscyamine effectively inhibited the attachment of conidia to the surface of rice (Oryza sativa) leaves and inhibited appressorium formation on the leaves. A high concentration of scopolamine (1000 μg/ml) also delayed or inhibited conidial germination in M. oryzae, but conidial germination was restored after washing the conidia with water. Antifungal activity of hyoscyamine was reduced by scopolamine. Magnaporthe oryzae infection was significantly suppressed (by >95%) in leaves of intact rice plants treated with hyoscyamine (10 μg/ml). Moreover, 10 μg hyoscyamine/ml significantly reduced the disease severity index for sheath blight to ≤0.2, when compared with the disease index of control plants (>7.0). Hyoscyamine (>20 μg/ml) completely inhibited sclerotial germination and development of R. solani by delaying the initiation, maturation, and melanization of the sclerotia. These results suggest that tropane alkaloids may be useful for controlling blast and sheath blight diseases of rice and for studying the mechanisms that regulate conidial germination in M. oryzae and sclerotial germination and development in R. solani.