A distinct tymovirus infecting Cassia hoffmannseggii in Brazil

Leaves of Cassia hoffmannseggii, a wild fabaceous species found in the Atlantic Forest, with a severe mosaic symptom were collected in Pernambuco State, Brazil. By transmission electron microscopy, two types of virus particles were found: the first was recognized as particles of a potyvirus, which was later identified as Cowpea aphid-borne mosaic virus; and the second was isometric and present in high concentration. The observation of vesicles at the periphery of chloroplasts suggested a tymovirus infection, which was confirmed by subsequent assays. A serological assay against several tymovirus antisera resulted in positive reaction of this tymo-like virus with an antiserum of Passion fruit yellow mosaic virus. By means of RT-PCR and using degenerated primers for the conserved region of RNA-dependent RNA polymerase (RdRp) gene of tymoviruses, a specific DNA fragment was amplified and sequenced. Based on this sequence, a specific forward primer was synthesized and successfully used to amplify the 3' terminal genome region, containing the partial RdRp gene and the complete coat protein (CP) sequences. The CP was 188 amino acids (aa) long, and the highest CP aa identity was observed with Kennedya yellow mosaic virus (61 %). Based on the current ICTV demarcation criterion, this isolate was considered as a distinct tymovirus and tentatively named as Cassia yellow mosaic-associated virus.

Growth potential of Salmonella spp. and Listeria monocytogenes in nine types of ready-to-eat vegetables stored at variable temperature conditions during shelf-life

Growth potential (delta) is defined as the difference between the population of a microorganism at the end of shelf-life of specific food and its initial population. The determination of 6 of Salmonella and Listeria monocytogenes in RTE vegetables can be very useful to determine likely threats to food safety. However, little is known on the behavior of these microorganisms in several RTE vegetables. Therefore, the aim of this study was to determine the delta of both pathogens in nine different types of RTE vegetables (escarole, collard green, spinach, watercress, arugula, grated carrot, green salad, and mix for yakisoba) stored at refrigeration (7 degrees C) and abuse temperature (15 degrees C). The population of aerobic microorganisms and lactic acid bacteria, including those showing antimicrobial activity has been also determined. Results indicated that L monocytogenes was able to grow (delta >= 0.5 log(10)) in more storage conditions and vegetables than Salmonella. Both microorganisms were inhibited in carrots, although a more pronounced effect has been observed against L monocytogenes. The highest 5 values were obtained when the RTE vegetables were stored 15 degrees C/6 days in collard greens (delta=3.3) and arugula (delta=3.2) (L monocytogenes) and arugula (delta=4.1) and escarole (delta=2.8) (Salmonella). In most vegetables and storage conditions studied, the counts of total aerobic microorganisms raised significantly independent of the temperature of storage (p<0.05). Counts of lactic acid bacteria were higher in vegetables partially or fully stored at abuse temperature with recovery of isolates showing antimicrobial activity. In conclusion, the results of this study show that Salmonella and L monocytogenes may grow and reach high populations in RTE vegetables depending on storage conditions and the definition of effective intervention strategies are needed to control their growth in these products. (C) 2012 Elsevier B.V. All rights reserved.

DEFICIENCY SYMPTOMS AND UPTAKE OF MICRONUTRIENTS BY CASTOR BEAN GROWN IN NUTRIENT SOLUTION

Castor bean is a nutrient-demanding species, but there is still little information on its micronutrient requirements. The objectives of this study were to evaluate the effects of levels of B (2.5, 12.5 and 25.0 mu mol L-1), Cu (0.05, 0.25 and 0.50 mu mol L-1), Mn (0.2, 1.0 and 2.0 mu mol L-1) and Zn (0.2, 1.0 and 2.0 mu mol L-1) in a nutrient solution on plant B, Cu, Mn and Zn concentrations and uptake, vegetative growth and fruit yield of castor bean "Iris", grown in greenhouse. The experiment was arranged in a completely randomized block design with three replicates. The first deficiency symptoms were observed for B, followed by Zn, Cu and Mn. The main changes in the cell ultrastructure due to lack of B were thickening of the cell walls and middle lamellae, distorted chloroplasts and tightly stacked thylakoids, besides the absence of starch grains. The Mn, Zn and Cu deficiencies led to disruption of chloroplasts, disintegration of thylakoids and absence of amyloplasts. The concentration and uptake of B, Cu, Mn, and Zn in castor bean plants increased with micronutrient supply in the solution. Fruit yield was drastically reduced by B and Mn deficiencies. On the other hand, the dry matter yield of the shoot and root of castor bean plants was not. In the treatment with full nutrient solution, the leaves accumulated 56 and 48 % of the total B and Mn taken up by the plants, respectively, and the seeds and roots 85 and 61 % of the total Cu and Zn taken up, respectively. This shows the high demand of castor bean Iris for B and Mn for fruit yield.

Effects of Natural Radiation, Photosynthetically Active Radiation and Artificial Ultraviolet Radiation-B on the Chloroplast Organization and Metabolism of Porphyra acanthophora var. brasiliensis (Rhodophyta, Bangiales)

We undertook a study of Porphyra acanthophora var. brasiliensis to determine its responses under ambient conditions, photosynthetically active radiation (PAR), and PAR+UVBR (ultraviolet radiation-B) treatment, focusing on changes in ultrastructure, and cytochemistry. Accordingly, control ambient samples were collected in the field, and two different treatments were performed in the laboratory. Plants were exposed to PAR at 60 mu mol photons m(-2) s(-1) and PAR+UVBR at 0.35 W m(-2) for 3 h per day during 21 days of in vitro cultivation. Confocal laser scanning microscopy analysis of the vegetative cells showed single stellate chloroplast in ambient and PAR samples, but in PAR+UVBR-exposed plants, the chloroplast showed alterations in the number and form of arms. Under PAR+UVBR treatment, the thylakoids of the chloroplasts were disrupted, and an increase in the number of plastoglobuli was observed, in addition to mitochondria, which appeared with irregular, disrupted morphology compared to ambient and PAR samples. After UVBR exposure, the formation of carpospores was also observed. Plants under ambient conditions, as well as those treated with PAR and PAR+UVBR, all showed different concentrations of enzymatic response, including glutathione peroxidase and reductase activity. In summary, the present study demonstrates that P. acanthophora var. brasiliensis shows the activation of distinct mechanisms against natural radiation, PAR and PAR+UVBR.

Antioxidant Activity of Brazilian Vegetables and Its Relation with Phenolic Composition

Vegetables are widely consumed in Brazil and exported to several countries. This study was performed to evaluate the phenolic content and antioxidant activity of vegetables commonly consumed in Brazil using five different methods, namely DPPH and ABTS free radical, beta-carotene bleaching, reduction of Fe3+ (FRAP), oxidative stability in Rancimat, and the chemical composition using gas chromatography-mass spectrometry (GC-MS). The content of phenolic compounds ranged from 1.2 mg GA/g (carrot) to 16.9 mg GA/g (lettuce). Vegetables presenting the highest antioxidant activity were lettuce (77.2 mu mol Trolox/g DPPH center dot; 447.1 mu mol F2+/g FRAP), turmeric (118.6 mu mol Trolox/g ABTS(center dot+); 92.8% beta-carotene), watercress and broccoli (protective factor 1.29-Rancimat method). Artichoke, spinach, broccoli, and asparagus also showed considerable antioxidant activity. The most frequent phenolic compounds identified by GC-MS were ferulic, caffeic, p-coumaric, 2-dihydroxybenzoic, 2,5-dihydroxybenzoic acids, and quercetin. We observed antioxidant activity in several vegetables and our results point out their importance in the diet.

Deficiency symptoms and uptake of micronutrients by castor bean grown in nutrient solution

Castor bean is a nutrient-demanding species, but there is still little information on its micronutrient requirements. The objectives of this study were to evaluate the effects of levels of B (2.5, 12.5 and 25.0 µmol L-1), Cu (0.05, 0.25 and 0.50 µmol L-1), Mn (0.2, 1.0 and 2.0 µmol L-1) and Zn (0.2, 1.0 and 2.0 µmol L-1) in a nutrient solution on plant B, Cu, Mn and Zn concentrations and uptake, vegetative growth and fruit yield of castor bean "Iris", grown in greenhouse. The experiment was arranged in a completely randomized block design with three replicates. The first deficiency symptoms were observed for B, followed by Zn, Cu and Mn. The main changes in the cell ultrastructure due to lack of B were thickening of the cell walls and middle lamellae, distorted chloroplasts and tightly stacked thylakoids, besides the absence of starch grains. The Mn, Zn and Cu deficiencies led to disruption of chloroplasts, disintegration of thylakoids and absence of amyloplasts. The concentration and uptake of B, Cu, Mn, and Zn in castor bean plants increased with micronutrient supply in the solution. Fruit yield was drastically reduced by B and Mn deficiencies. On the other hand, the dry matter yield of the shoot and root of castor bean plants was not. In the treatment with full nutrient solution, the leaves accumulated 56 and 48 % of the total B and Mn taken up by the plants, respectively, and the seeds and roots 85 and 61 % of the total Cu and Zn taken up, respectively. This shows the high demand of castor bean Iris for B and Mn for fruit yield.