Atividade antagônica in vitro de isolados de Trichoderma spp. ao fungo Phytophthora citrophthora

Gummosis is among the main fungal diseases of the citrus. It is caused by Phytophthora sp. and usually shows up in the lap of the plant, provoking rottenness and gum exudation, and expands causing the plant death for constrictions in the cambium or phloem which interrupts the descending flow of sap. The objective of this work was to evaluate the antagonistic in vitro activity of Trichoderma spp. to the fungi Phytophthora citrophthora. Phytophthora citrophthora was exposed to five environments of antagonism (without antagonist and with four strains of Trichoderma viride, T. virens, T. harzianu and T stromaticum), The in vitro essay was accomplished through the method of paired cultures. A completely randomized desing was used with five treatments and three replications, and each plot was represented by three petri dishes. The isolates of Trichoderma demonstrated significant effect in the inhibition of the mycelial growth of the fungi Phytophthora citrophthora, and the fungi Trichoderma stromaticum presented larger antagonism to the fungi P. citrophthora while the T harzianum presented antagonism smaller.

Relationships among Pratylenchus jaehni and P. coffeae populations from Brazil.

Wilcken, S.R.S., E.S. Mori, M. Bacci, L.C.C.B. Ferraz, C.M.G. Oliveira & M.M. Inomoto. 2008. Relationships among Pratylenchus jaehni and P. coffeae populations from Brazil. The relationships among Pratylenchus jaehni (C) and six amphimitic Pratylenchus populations from Brazil (three from banana, PcB1, PcB2, and PcB3; one from Aglaonema sp., M2; one from coffee, K5; and one from citrus, C) were studied through morphological and molecular analysis, and pathogenicity test. The analysis of morphometric characteristics of PcB1, M2, C2 and K5, compared with P. jaehni and P. coffeae (K6) data obtained from literature, delineated three groups: P. coffeae (K6), PcB1 and M2; P. jaehni (C1) and C2; and K5. RAPD analysis of PcB1, PcB2, PcB3, M2, C2, K5 and P.jaehni (C1) demonstrated that these populations form three distinct genetic groups: PcB1, PcB2, PcB3 and M2; P.jaehni and C2; and K5. In pathogenicity test, K5 reproduced well on coffee and caused extensive root necrosis, but C2 did not. Population C2 reproduced well on Rangpur lime, which was previously rated as poor host to K5. Therefore, the results demonstrated that C2 is P. jaehni, K5 is an undescribed species of Pratylenchus, and PcB1, PcB2 and PcB3 are P. coffeae. The taxonomic status of M2 remains inconclusive.

Mosca-Negra-dos-Citros: Características Gerais, Bioecologia e Métodos de Controle dessa Importante Praga Quarentenária da Citricultura Brasileira

Citrus blackfly, Aleurocanthus woglumi Ashby, is a serious pest of citrus culture and other economically important fruit crops. It is a present quarantine pest or A2 maximum alert restricting trades with other regions free of its presence. Since the frst occurrence of the citrus blackfly in Belem in 2001 its dissemination was quickly to other States and regions of citrus production in Brazil. As an exotic pest, basic knowledge is scarce in order to establish the appropriate management to the insect in Brazil. Thus, the aim of the present study was to provide information about important aspects of A. woglumi, such as: history and geographical distribution, bioecology, host plants, appropriate control methods, among others, in order to provide subsidies for futures researches about the citrus blackfly in Brazil.

Synergistic actions of 50°C water and imazalil dip treatments to preserve quality of late-season 'Marsh' grapefruit

Late-season grapefruits (Citrus paradisi Macf. cv. Marsh seedless) were dipped in water at 50°C for 3 min with and without 200 ppm imazalil (IMZ) or 1000 ppm IMZ at 19°C and were subsequently stored at 7°C and 90-95% relative humidity (RH) for 11 weeks plus one week at 21°C and approximately 75% RH to simulate a marketing period (SMP). Residue concentrations in fruit after treatment with 200 ppm IMZ at 50°C were 3.46 ppm, about twice the level (1.80 ppm) found in fruit treated with 1000 ppm IMZ at 19°C. Fungicide degradation rates during storage showed similar patterns resulting in an approximately 50% decrease. Both fungicide treatments significantly reduced decay and chilling injury (CI) during storage and SMP. Hot water reduced CI and decay but not as effectively as the IMZ treatments. Soluble solids concentrations were not affected by treatments, IMZ treatments resulted in significantly lower values of titratable acidity and higher concentrations of ethanol in the juice after SMP. Weight loss was significantly higher in fruit dipped in water at 50°C after SMP. No visible damage occurred to the fruit as a result of any of the treatments.

Effects of G a3 dosis associated with organosilicone on sweet oranges in Brazil

GA3 was tested in sweet oranges 'Pera' and 'Hamlin' for delay the picking time without loosening of fruit quality for processing. Hamlin is the firths cv processed in Brazil and Pera is a mid season cv and extending their period of processing is important. Two experiments were made at the Citrus Experimental Station during 1996 season. The treatments are 5 ppm of GA 3 + 0,05% Silwett L-77® (organosilicone), 10 ppm of GA 3 + 0,05% of Silwet L-77®, 20 ppm of GA3 + 0,1% Herbitensil® (Noniphenoloxietilate 40%m/v + isopropilic alcohol 15% m/v) and control, repeated 7 times for Hamlin and 8 times for Pera, with one tree each parcel. The treatments were applied in May 1996, at the stage of greenish yellow colour of the fruits. Evaluations were made each 20 days interval till the final picking, It was analysed fruit quality and retention force for picking and puncture resistance. The results showed no differences for fruit quality of Hamlin from July to mid September and for Pera till September. After some differences occurred. The GA3 treatments were effectives in maintain the fruit retention force for both cvs for 120 days after application. In relation to fruit puncture resistance the treatments with GA3 differed of the control for both cvs, accordingly with the doses and mixtures. The colour index was better maintained with 5ppm of GA3 plus 0,05% of Silwet L-77®. The total fruit production did not differ for both cultivars.

Occurrence, distribution, and relative incidence of five viruses infecting cucurbits in the state of Sao Paulo, Brazil

Cucurbits species grown in 38 of 40 agricultural regions in the state of Sao Paulo, Brazil, were surveyed for the relative incidence of Cucumber mosaic virus (CMV), Papaya ringspot virus-type W (PRSV-W), Watermelon mosaic virus-2 (WMV-2), Zucchini lethal chlorosis virus (ZLCV), and Zucchini yellow mosaic virus (ZYMV) during May 1997 and June 1999. Samples from 621 plants, representing eight cultivated species, six wild species, and one commercial hybrid (Cucurbita moschata x C. maxima), were analyzed by plate trapped antigen enzyme-linked immunosorbent assay (PTA-ELISA). PRSV-W and ZYMV were the most frequently found viruses, accounting for 49.1 and 24.8%, respectively, of 605 samples tested. ZLCV, CMV, and WMV-2 were detected in 7.8, 6.0, and 4.5% of 612, 497, and 423 samples tested, respectively. Double infection was found in 97 samples, and triple infection was found in 10 samples. Quadruple infection was detected in one C. pepo sample. Plants that were symptomatic but negative by PTA-ELISA might be due to abiotic agents, infection by virus for which antiserum was not available, such as Squash mosaic virus, or infection with an as yet uncharacterized virus.

Design of microirrigation systems in sloping lands using linear programming

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Economic viability and selection of irrigation systems using simulation and stochastic dominance

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Transposon Tn1721 distribution among strains of Xylella fastidiosa

Transposons are mobile genetic elements found within the genomes of various organisms including bacteria, fungi, plants and animals. Fragments of the transposon Tn1721 were found included in the genome of Xylella fastidiosa strain 9a5c. Regions from such fragments were PCR-amplified using specially designed primers (TNP1 and TNP2). In order to detect insertions of the Tn1721 element, both primers were used and one of them included a region of the transposon (TNP1) and the other one had the right repeat and part of the bacterial chromosome (TNP2). The PCR products obtained from strain 9a5c were used as a pattern for fragment size comparisons when DNA samples from other X. fastidiosa strains were used as template for the PCR assays. Differences were observed concerning the PCR products of such amplifications when some X. fastidiosa strains isolated from grapevine and plum were used. For the citrus-derived strains only the strains U187d and GP920b produced fragments with different sizes or weak band intensity. Such variations in the X. fastidiosa genome related to disrupted Tn1721 copies are probably due to the possibility of such a transposon element being still able to duplicate even after deletion events might have taken place and also because the bacterial strains in which the main differences were detected are derived from different host plants cultivated under different climate conditions from the one used as reference. © 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.

A review of antifertility folkloric plants tested in laboratory animals

The use of natural active principals is widespread among a great proportion of the rural population, or by people who do not have easy access to medical assistance. These active principles are used as food or medicines, and even for purposes of contraception. It becomes necessary to establish a relationship between the folklore habits and current information on the nature of anti-fertility substances, and knowledge of their mechanisms. Anti-fertility agents may exert their actions in a number of areas, (hypothalamus, anterior pituitary, oviduct, uterus, and vagina), inhibiting synthesis and/or liberation of hormones (follicle-stimulating, luteinizing, and steroid hormones), ovulation, ovum transportation, and implantation process. Therefore, a review of literature was carried out, including of several plants used by women as abortifacient and anti-fertility agents to compare their effects with those obtained among laboratory animals.

Alimentary preconditioning in Acromyrmex subterraneus brunneus workers

Ants suffer a strong environmental influence and are sometimes conditioned for many social activities. To understand better this phenomenon in leaf-cutting ants, 24 colonies of Acromyrmex subterraneus brunneus (Hymenoptera: Formicidae) were conditioned for 2 months with 6 different plants (Citrus spp., Ligustrum spp., Acalypha spp., Eucalyptus spp., Alchornea triplinervia, Melia spp.), to verify alimentary preconditioning in plant selection. After the conditioning period, plants were offered simultaneously, to evaluate the acceptability of each plant species. During foraging, the workers did not exhibit alimentary source fidelity, which was familiarized. This fact suggests the absence of alimentary preconditioning, reinforcing the polyphagic foraging behavior of leaf-cutting ants.

The effect of plant diversity on fungus garden development and foraging behavior of leaf-cutting ants (Hymenoptera: Formicidae)

The leaf-cutting ants forage a wide variety of plant species, used for symbiotic fungus cultivation. To better understand this tripartite complex interaction, 24 colonies of Acromyrmex subterraneus brunneus were conditioned for 4 months to 6 different plants (Citrus spp., Ligustrum spp., Acalypha spp., Eucalyptus spp., Alchornea triplinervia, Melia spp.), to verify the influence of conditioning on foraging behavior of workers. The effect of plants on symbiotic fungus development was studied separately, through macerated plants in Agar and culture medium A as the control. During foraging, workers presented polyphagic foraging behavior, refusing the plants to which they were conditioned. The selection of plants is not correlated with the plant substrate that promotes good development of symbiotic fungus. Such results demonstrate the importance of plant diversity for fungus garden maintenance.

Eficiência de extratos de plantas medicinais e aromáticas em atrair a abelha africanizada (Apis mellifera L.) em cultura de abacateiro (Persea americana Mili.)

The objective of the experiment was to test attractive substances for Africanized honey bees, Apis mellifera L., in avocado, Persea americana Mill. Were pulverized extracts of lemon grass (Cympobogon citratus), ocimum (Ocimum sellowii), Lippia alba, orange leaves (Citrus sinensis), eucaliptus leaves (Eucalyptus sp), eugenol and linalol and the frequency of bees on flowers were evaluated. The frequency of honey bees did increase with the application of the extracts falsa melissa, eucaliptus leaves and orange leaves, used as attractants in Quintal variety. The products tested in Eppendorf tubes did not increased the frequency the bees in Quintal and Fortuna varieties.

Putative pyrophosphate phosphofructose 1-kinase genes identified in sugarcane may be getting energy from pyrophosphate

Pyrophosphate-dependent phosphofructokinase (PPi-PFK) has been detected in several types of plant cells, but the gene has not been reported in sugar cane. Using Citrux paradixi PPi-PFK gene (AF095520 and AF095521) sequences to search the sugar cane EST database, we have identified both the α and β subunits of this enzyme. The deduced amino acid sequences showed 76 and 80% similarity with the corresponding α and β subunits of C. paradisi. A high degree of similarity was also observed among the PFK β subunits when the alignment of the sugar cane sequences was compared to those of Ricinus communis and Solanum tuberosum, it appears that α and β are two distinct subunits; they were found at different concentrations in several sugar cane tissues. It remains to be determined if the different gene expression levels have some physiological importance and how they affect sucrose synthesis, export, and storage in vacuoles. A comparison between the amino acid sequences of β PFKs from a variety of organisms allowed us to identify the two critical Asp residues typical of this enzyme's activity site and the other binding sites; these residues are tightly conserved in all members of this protein family. Apparently, there are catalytic residues on the β subunit of the pyrophosphate-dependent enzyme.

Isolamento de fungos produtores de enzimas pectinolíticas

Soil samples collected in the campus, UNESP, Araraquara, SP, were employed to isolate and characterize fungi strains with potential pectinolytic enzymes. These enzymes have arisen great interest due to its increasing application in the food industry. Two hundred forty six strains were isolated based on the appearance of colony on PDA medium, morphology (septate mycelia, nonseptate conidiophore, black conidia, and clublike spore-bearing head), after 48 h of growth at 30°C. Strains were selected in solid medium containing pectin citrus as sole carbon source and 0.5% rutenium red. The characterization of pectinolytic production was performed in solid culture and batch fermentation medium containing pectin citrus. The enzyme pectinolytic production was evaluated at 30°C, without agitation in 100 mL of medium containing 2% pectin citrus, 0.2% ammonium sulphate, 0.2% magnesium sulphate, and 0.05% potassium phosphate. The maximum pectinolytic activity (15U/mL) was observed in the medium after Aspergillus sp CFCF-0492 growth, while Aspergillus sp CFCF-CC1 showed the higher level of the final biomass. The pectinolytic activity is more preserved when the fungi-spores were maintained in agar-Czapeck medium.