Probable consequences of the mitigation of citrus canker eradication methodology in Sao Paulo state

Probable consequences of the mitigation of citrus canker eradication methodology in Sao Paulo state Recently the Sao Paulo state government mitigated its citrus canker eradication methodology adopted since 1999. In April 2009 at least 99.8% of commercial sweet orange orchards were free of citrus canker in Sao Paulo state. Consequently the mitigation of the eradication methodology reduced the high level of safety and the competitiveness of the citrus production sector in Sao Paulo state, Brazil. Therefore we suggest the re-adoption of the same eradication methodology of citrus canker adopted in Sao Paulo from 1999 to 2009, or the adoption of a new methodology, effective for citrus canker suppression, because in new sample surveys citrus canker was detected in >0.36% of affected orchards. This incidence threshold was calculated by using the Duncan test (P <= 0.05) to compare the yearly sample surveys conducted in Sao Paulo state to estimate citrus canker incidence between 1999 and 2009. The calculated minimum significant level was 0.28% among sample surveys and the lowest citrus canker incidence in Sao Paulo state was 0.08%, occurring in 2001. Thus, as an alternative, we suggest the adoption of a new eradication methodology for citrus canker suppression when a new sample survey detected >0.36% of affected orchards in Sao Paulo state, Brazil.

Characterization and Experimental Host Range of a Brazilian Tomato Isolate of Tomato severe rugose virus

We report the complete molecular characterization of the DNA-A and DNA-B of a Brazilian tomato isolate of Tomato severe rugose virus (ToSRV) and the experimental host range of the virus determined using white-fly transmission tests. Genome analysis showed that ToSRV has a close evolutionary relationship with Tomato rugose mosaic virus. Of 33 plants species inoculated with viruliferous Bemisia tabaci biotype B, 13 species were susceptible to ToSRV, nine asymptomatically. Therefore, ToSRV disease management strategy should include the control of infected weeds close to tomato fields.

Natural infection of Nicandra physaloides by Tomato severe rugose virus in Brazil

Nicandra physaloides, a common weed in South America, was found to be infected by an isolate of Tomato severe rugose virus (ToSRV), a bipartite begomovirus. The plants developed severe yellow rugose mosaic and were collected in So Paulo State, Brazil. This isolate of ToSRV was transmitted by Bemisia tabaci B biotype from infected plants of N. physaloides to healthy plants of N. physaloides and tomato in a glasshouse. This is the first report of natural infection of N. physaloides by ToSRV in Brazil.

Prepenetration Stages of Guignardia psidii in Guava: Effects of Temperature, Wetness Duration and Fruit Age

This study examined the effects of temperature and wetness duration in vitro and in vivo as well as the effects of fruit age on germination and appressoria formation by conidia of Guignardia psidii, the causal agent of black spot disease in guava fruit. The temperatures tested for in vitro and in vivo experiments were 10, 15, 20, 25, 30, 35 and 40 degrees C. The wetness periods studied were 6, 12, 24, 36 and 48 h in vitro and 6, 12 and 24 h in vivo. Fruit 10, 35, 60, 85 and 110-days old were inoculated and maintained at 25 degrees C, with a wetness period of 24 h. Temperature and wetness duration affected the variables evaluated in vitro and in vivo. All variables reached their maximum values at between 25 and 30 degrees C with a wetness duration of 24 h in vivo and 48 h in vitro. These conditions resulted in 31.3% conidia germination, 33.6% appressoria formation and 32.5% appressoria melanization in vitro, and 50.4% conidia germination and 9.5% appressoria formation in vivo. Fruit age also influenced these factors. As fruit age increased, conidia germination and appressoria formation gradually increased. Conidia germination and appressoria formation were 10.8% and 2.3%, respectively, in 10-day-old fruits. In 110-day-old fruits, conidia germination and appressoria formation were 42.5% and 23.2% respectively.

Chlorophyll a fluorescence and ultrastructural changes in chloroplast of water hyacinth as indicators of environmental stress

Chlorophyll a fluorescence parameters and transmission electron microscopy (TEM) were used to assess the stress conditions in water hyacinth along the Paraiba do Sul River (PSR), an important River in southeastern Brazil. The data were obtained at the end of the dry season of 2005 and at the end of the wet season of 2006. Changes in F-o and F-m parameters were observed as differentiated responses, depending on the season. Non-photochemical dissipation (qN and NPQ) from plants was greater in the most industrialized region of the PSR in both seasons. However, F-v/F-m for all samples ranged between 0.77 and 0.81, showing that high maximum quantum yield was maintained. Although the F-v/F-m suggests that the plants were exhibiting normal photochemical activities, ultrastructural changes in chloroplasts showed thylakoids disorganization. Plants from the most industrialized region showed non-stacking grana thylakoids disposition. In spite of these alterations, the membrane integrity was maintained, suggesting an adaptation to adjustment to adverse environmental conditions. (C) 2008 Elsevier B.V. All rights reserved.

An integrated molecular map of yellow passion fruit based on simultaneous maximum-likelihood estimation of linkage and linkage phases

The development of genetic maps for auto-incompatible species, such as the yellow passion fruit (Passiflora edulis Sims f.flavicarpa Deg.) is restricted due to the unfeasibility of obtaining traditional mapping populations based on inbred lines. For this reason, yellow passion fruit linkage maps were generally constructed using a strategy known as two-way pseudo-testeross, based on monoparental dominant markers segregating in a 1:1 fashion. Due to the lack of information from these markers in one of the parents, two individual (parental) maps were obtained. However, integration of these maps is essential, and biparental markers can be used for such an operation. The objective of our study was to construct an integrated molecular map for a full-sib population of yellow passion fruit combining different loci configuration generated from amplified fragment length polymorphisms (AFLPs) and microsatellite markers and using a novel approach based on simultaneous maximum-likelihood estimation of linkage and linkage phases, specially designed for outcrossing species. Of the total number of loci, approximate to 76%, 21%, 0.7%, and 2.3% did segregate in 1:1, 3:1, 1:2:1, and 1:1:1:1 ratios, respectively. Ten linkage groups (LGs) were established with a logarithm of the odds (LOD) score >= 5.0 assuming a recombination fraction : <= 0.35. On average, 24 markers were assigned per LG, representing a total map length of 1687 cM, with a marker density of 6.9 cM. No markers were placed as accessories on the map as was done with previously constructed individual maps.

Inheritance of growth habit detected by genetic linkage analysis using microsatellites in the common bean (Phaseolus vulgaris L.)

The genetic linkage map for the common bean (Phaseolus vulgaris L.) is a valuable tool for breeding programs. Breeders provide new cultivars that meet the requirements of farmers and consumers, such as seed color, seed size, maturity, and growth habit. A genetic study was conducted to examine the genetics behind certain qualitative traits. Growth habit is usually described as a recessive trait inherited by a single gene, and there is no consensus about the position of the locus. The aim of this study was to develop a new genetic linkage map using genic and genomic microsatellite markers and three morphological traits: growth habit, flower color, and pod tip shape. A mapping population consisting of 380 recombinant F10 lines was generated from IAC-UNA x CAL143. A total of 871 microsatellites were screened for polymorphisms among the parents, and a linkage map was obtained with 198 mapped microsatellites. The total map length was 1865.9 cM, and the average distance between markers was 9.4 cM. Flower color and pod tip shape were mapped and segregated at Mendelian ratios, as expected. The segregation ratio and linkage data analyses indicated that the determinacy growth habit was inherited as two independent and dominant genes, and a genetic model is proposed for this trait.

Transgenic Sweet Orange (Citrus sinensis L. Osbeck) Expressing the attacin A Gene for Resistance to Xanthomonas citri subsp citri

Genetic transformation with genes that code for antimicrobial peptides has been an important strategy used to control bacterial diseases in fruit crops, including apples, pears, and citrus. Asian citrus canker (ACC) caused by Xanthomonas citri subsp. citri Schaad et al. (Xcc) is a very destructive disease, which affects the citrus industry in most citrus-producing areas of the world. Here, we report the production of genetically transformed Natal, Pera, and Valencia sweet orange cultivars (Citrus sinensis L. Osbeck) with the insect-derived attacin A (attA) gene and the evaluation of the transgenic plants for resistance to Xcc. Agrobacterium tumefaciens Smith and Towns-mediated genetic transformation experiments involving these cultivars led to the regeneration of 23 different lines. Genetically transformed plants were identified by polymerase chain reaction, and transgene integration was confirmed by Southern blot analyses. Transcription of attA gene was detected by Northern blot analysis in all plants, except for one Natal sweet orange transformation event. Transgenic lines were multiplied by grafting onto Rangpur lime rootstock plants (Citrus limonia Osbeck) and spray-inoculated with an Xcc suspension (10(6) cfu mL(-1)). Experiments were repeated three times in a completely randomized design with seven to ten replicates. Disease severity was determined in all transgenic lines and in the control (non-transgenic) plants 30 days after inoculation. Four transgenic lines of Valencia sweet orange showed a significant reduction in disease severity caused by Xcc. These reductions ranged from 58.3% to 77.8%, corresponding to only 0.16-0.30% of leaf diseased area as opposed to 0.72% on control plants. One transgenic line of Natal sweet orange was significantly more resistant to Xcc, with a reduction of 45.2% comparing to the control plants, with only 0.14% of leaf diseased area. Genetically transformed Pera sweet orange plants expressing attA gene did not show a significant enhanced resistance to Xcc, probably due to its genetic background, which is naturally more resistant to this pathogen. The potential effect of attacin A antimicrobial peptide to control ACC may be related to the genetic background of each sweet orange cultivar regarding their natural resistance to the pathogen.

A new variety of the weed Borreria densiflora DC. (Rubiaceae)

The weed, known commonly as vassourinha de botao (buttonweed), is present in several crops in northern and north-eastern Brazil. Its occurrence is common in sugarcane and soybean crops in the states of Goias, Tocantins, and Maranhao. However, there is no published information in the literature about its taxonomic classification. Thus, this research aimed to classify taxonomically this species in order to develop a classification key based on the morphological characteristics among varieties of Borreria densiflora DC., as well as to illustrate it and provide a palynological basis to classify this species as a new variety For the classification process, data from the literature, morphological characteristics, and palynological evidence were considered. In this article, we describe a new variety, B. densiflora DC. var. latifolia E.L. Cabral & Martins. The new variety possesses a terrestrial habitat and it is a simple perennial weed species. These results show the importance of an accurate identification, as well as an understanding of the evolutionary changes inherent to weeds (like intraspecific variability), breeding system, genetic potential, and ecological studies. Those factors are essential to the beginning of a long-term weed management strategy.

Genetic transformation of Citrus sinensis cv. Hamlin with hrpN gene from Erwinia amylovora and evaluation of the transgenic lines for resistance to citrus canker

Transgenic Citrus sinensis (L.) Osb. cv. Hamlin plants expressing the hrpN gene were obtained by Agrobacterium tumefaciens (Smith and Towns) Conn-mediated transformation. hrpN encodes a harpin protein, which elicits the hypersensitive response and systemic acquired resistance in plants. The gene construct consisted of gst1, a pathogen-inducible promoter, a signal peptide for protein secretion to the apoplast, the selection genes nptI1 or aacC1 and the Nos terminator. The function of gst1 in citrus was evaluated in transgenic C. sinensis cv. Valencia harboring the reporter gene uidA (gus) driven by this promoter. Histochemical analysis for gus revealed that gst1 is activated in citrus leaves by both wounding and inoculation with Xanthomonas axonopodis Starr and Garces pv. citri (Hasse) Vauterin et al. Genetic transformation was confirmed by Southern blot hybridization in eight cv. Hamlin acclimatized plants. RT-PCR confirmed hrpN gene expression in seven cv. Hamlin transgenic lines before pathogen inoculation. Some hrpN transgenic lines showed severe leaf curling and abnormal growth. Six hrpN transgenic lines were propagated and evaluated for susceptibility to X axonopodis pv. citri. RT-PCR confirmed gene expression in all six hrpN transgenic lines after pathogen inoculation. Several of the hrpN transgenic lines showed reduction in susceptibility to citrus canker as compared with non-transgenic plants. One hrpN transgenic line exhibited normal vegetative development and displayed very high resistance to the pathogen, estimated as up to 79% reduction in disease severity. This is the first report of genetic transformation of citrus using a pathogen-inducible promoter and the hrpN gene. Further evaluations of the transgenic plants under field conditions are planned. Nevertheless, the evidence to date suggests that the hrpN gene reduces the susceptibility of citrus plants to the canker disease. (C) 2009 Elsevier B.V. All rights reserved.

Nitrogen, phosphorus and potassium dose effect in the graft box of lemon tree (of the family Rutaceae) nutrition and production.

Nitrogen, phosphorus and potassium dose effect in the graft box of lemon tree (of the family Rutaceae) nutrition and production. The aim of the study was to evaluate the graft box of lemon tree (of the family Rutaceae) nutritional state and its components of growth in function of nitrogen, phosphorus and potassium dose by fertilization. The experimental outlining was entirely made casually in factorial scheme 3(3) + 1, being 3 factors (nitrogen, phosphorus and potassium - NPK), 3 doses and in evidence (without fertilization), with 3 repetitions. The experimental milt was constituted by two tubes of 2,8 cm diameter and 12,3 cm high with a graft box (Hipobioto) of lemon tree (of the family Rutaceae) in each tube. The doses used were constituted by doses of N (460; 920 e 18,10 mg dm(-3)), P (50; 100 e 200 mg dm(-3)) and K (395; 790 e 1580 mg dm(-3)). The fertilization with N and K was carried out by fertirrigations and the P added to the substract of Pinus rind and vermiculite before the seeding. when the plants were 133 days after the germination they were subdivided in radicular system and air part for the determinations of the dry matter mass, height, foliar area, stem diameter and contents of nutrients. The N, K and P doses of 920 mg dm(-3), 790 mg dm(-3), 100 mg dm(-3), respectively, were enough for the suitable development of the graft box of lemon tree (of the family Rutaceae) in tubes.

IN VITRO GERMINATION OF GRAINS POLLEN OF Prunus persica (L.) BATSCH vulgaris

The objective was to adjust a protocol for peach pollen grains in vitro germination. For that, were realized five experiments with the purpose of establish the ideal concentration of sucrose, agar, calcium nitrate, boric acid, the best pH value, the germination temperature and the polinic tube emission time. As vegetal material, was used the Aurora 1 and Douradao cultivars. For the Aurora 1 cultivar, higher germination of pollen grains was obtained with the use of 48,29 g. L(-1) of sucrose, 10 g. L(-1) of agar, 400 mg.L(-1) of boric acid and pH 5,5. For the Douradao cultivar, higher germination was obtained on medium containing 90 g.L(-1) of sucrose, 10 g.L(-1) of agar, 400 mg.L(-1) of boric acid, 369 mg.L(-1) of calcium nitrate and pH 6,5. The best temperature for the germination of the pollen grains for both cultivars was 25 degrees C, being the pollen grains germination percentage raising proportionally directly to the evaluation time.

A correct enthalpy relationship as thermal comfort index for livestock

Researchers working with thermal comfort have been using enthalpy to measure thermal energy inside rural facilities, establishing indicator values for many situations of thermal comfort and heat stress. This variable turned out to be helpful in analyzing thermal exchange in livestock systems. The animals are exposed to an environment which is decisive for the thermoregulatory process, and, consequently, the reactions reflect states of thermal comfort or heat stress, the last being responsable for problems of sanity, behavior and productivity. There are researchers using enthalpy as a qualitative indicator of thermal environment of livestock such as poultry, cattle and hogs in tropical regions. This preliminary work intends to check different enthalpy equations using information from classical thermodynamics, and proposes a direct equation as thermal comfort index for livestock systems.

Residential high-rise buildings in São Paulo: aspects related to the adequacy to the occupant`s needs

This paper analyzes the production of apartment buildings for the middle-income segment in the city of So Paulo, Brazil, from a historical perspective. Tracing the response to the occupants` needs, the focus is on family profiles and their demands, the relationship between architectural design and marketing, and satisfaction levels of current users. The paper begins with a brief historical overview of how apartment buildings have evolved over the past eight decades, highlighting the consolidation of the tripartite model. Next, it analyzes family profiles and their current needs, which would call for a redesign of domestic space. From a different angle, it shows how the real-estate market reacts to this situation, namely by introducing minor changes in the domestic space that are closely linked to major investments in marketing. This leads to a discussion on the quality of recent architectural designs in light of Post-Occupancy Evaluation (POE) case studies, which corroborate the tendencies previously outlined. The conclusions drawn from the POEs suggest that the market should establish a closer and deeper relationship between the assessment of the human behavior in the domestic space and the architectural quality of homes as a means of increasing satisfaction levels and improving design performance.