Characterization of mandarin citrus germplasm from Southern Brazil by morphological and molecular analyses

The objective of this work was to characterize mandarin (Citrus spp.) germplasm from Southern Brazil by morphological and molecular analyses. Thirty seven cultivars from 34 distinct mandarin varieties were evaluated by morphological and agronomic traits of leaves, flowers and fruits, and by microsatellite markers. The morphological and agronomic characteristics suggested that almost all varieties can be produced for commercial use, and some, as the Satsuma variety, are recommended for breeding programs. Pooled DNA samples from 1-5 plants belonging to each cultivar were tested. Eight of the nine primers detected polymorphisms. Specific markers were found for some accessions. The dendrogram constructed with the morphological results divided the 37 cultivars into four groups, while that obtained with the microsatellites clustered 35 of the 37 cultivars into three groups only. Generally, intervarietal differences are not high, and this lack of agreement in the two multifactorial analyses indicates that diverse evolutionary factors are acting at these two levels of investigation.

Sweet orange trees grafted on selected rootstocks fertilized with nitrogen, phosphorus and potassium

The majority of citrus trees in Brazil are grafted on 'Rangpur lime' (Citrus limonia Osb.) rootstock. Despite its good horticultural performance, search for disease tolerant rootstock varieties to improve yield and longevity of citrus groves has increased. The objective of this work was to evaluate yield efficiency of sweet oranges on different rootstocks fertilized with N, P, and potassium. Tree growth was affected by rootstock varieties; trees on 'Swingle' citrumelo [Poncirus trifoliata (L.) Raf. × C. paradisi Macf.] presented the smallest canopy (13.3 m³ in the fifth year after tree planting) compared to those on 'Rangpur lime' and 'Cleopatra' mandarin [C. reshni (Hayata) hort. ex Tanaka] grown on the same grove. Although it was observed an overall positive relationship between canopy volume and fruit yield (R² = 0.95**), yield efficiency (kg m-3) was affected by rootstocks, which demonstrated 'Rangpur lime' superiority in relation to Cleopatra. Growth of citrus trees younger than 5-yr-old might be improved by K fertilization rates greater than currently recommended in Brazil, in soils with low K and subjected to nutrient leaching losses.

Nitrogen fixation by groundnut and velvet bean and residual benefit to a subsequent maize crop

Chemical fertilisers are rarely avaiable to poor farmers, for whom the nitrogen (N) is often the most limiting element for cereal grain production. The objective of this study was to quantify the contribution of biological nitrogen fixation (BNF) to groundnut (Arachis hypogaea) and velvet bean (Mucuna pruriens) crops using the 15N natural abundance (delta15N) technique and to determine their residual effect and that of a natural fallow, on growth and N accumulation by two rustic maize varieties. The contribution of BNF calculated from delta15N data was 40.9, 59.6 and 30.9 kg ha-1, for groundnut, velvet bean and the natural fallow, respectively. The only legume grain harvested was from the groundnut, which yielded approximately 1.000 kg ha-1. The subsequent maize varieties ("Sol de Manhã" and "Caiana Sobralha") yielded between 1.958 and 2.971 kg ha-1, and were higher after velvet bean for both maize varieties and "Sol da Manhã" groundnut, followed by "Caiana" after groundnut and, finally, the natural fallow. For a small-holder producer the most attractive system is the groundnut followed by maize, as, in this treatment, both groundnut and maize grain harvest are possible. However, a simple N balance calculation indicated that the groundnut-maize sequence would, in the long term, deplete soil N reserves, while the velvet bean-maize sequence would lead to a build up of soil nitrogen.

Spatial statistical analysis and selection of genotypes in plant breeding

The objective of this study was to evaluate the efficiency of spatial statistical analysis in the selection of genotypes in a plant breeding program and, particularly, to demonstrate the benefits of the approach when experimental observations are not spatially independent. The basic material of this study was a yield trial of soybean lines, with five check varieties (of fixed effect) and 110 test lines (of random effects), in an augmented block design. The spatial analysis used a random field linear model (RFML), with a covariance function estimated from the residuals of the analysis considering independent errors. Results showed a residual autocorrelation of significant magnitude and extension (range), which allowed a better discrimination among genotypes (increase of the power of statistical tests, reduction in the standard errors of estimates and predictors, and a greater amplitude of predictor values) when the spatial analysis was applied. Furthermore, the spatial analysis led to a different ranking of the genetic materials, in comparison with the non-spatial analysis, and a selection less influenced by local variation effects was obtained.

Sequence similarity between the viral cp gene and the transgene in transgenic papayas

The Papaya ringspot virus (PRSV) coat protein transgene present in 'Rainbow' and 'SunUp' papayas disclose high sequence similarity (>89%) to the cp gene from PRSV BR and TH. Despite this, both isolates are able to break down the resistance in 'Rainbow', while only the latter is able to do so in 'SunUp'. The objective of this work was to evaluate the degree of sequence similarity between the cp gene in the challenge isolate and the cp transgene in transgenic papayas resistant to PRSV. The production of a hybrid virus containing the genome backbone of PRSV HA up to the Apa I site in the NIb gene, and downstream from there, the sequence of PRSV TH was undertaken. This hybrid virus, PRSV HA/TH, was obtained and used to challenge 'Rainbow', 'SunUp', and an R2 population derived from line 63-1, all resistant to PRSV HA. PRSV HA/TH broke down the resistance in both papaya varieties and in the 63-1 population, demonstrating that sequence similarity is a major factor in the mechanism of resistance used by transgenic papayas expressing the cp gene. A comparative analysis of the cp gene present in line 55-1 and 63-1-derived transgenic plants and in PRSV HA, BR, and TH was also performed.

Location-independent and location-linked representations of sound objects.

For the recognition of sounds to benefit perception and action, their neural representations should also encode their current spatial position and their changes in position over time. The dual-stream model of auditory processing postulates separate (albeit interacting) processing streams for sound meaning and for sound location. Using a repetition priming paradigm in conjunction with distributed source modeling of auditory evoked potentials, we determined how individual sound objects are represented within these streams. Changes in perceived location were induced by interaural intensity differences, and sound location was either held constant or shifted across initial and repeated presentations (from one hemispace to the other in the main experiment or between locations within the right hemispace in a follow-up experiment). Location-linked representations were characterized by differences in priming effects between pairs presented to the same vs. different simulated lateralizations. These effects were significant at 20-39 ms post-stimulus onset within a cluster on the posterior part of the left superior and middle temporal gyri; and at 143-162 ms within a cluster on the left inferior and middle frontal gyri. Location-independent representations were characterized by a difference between initial and repeated presentations, independently of whether or not their simulated lateralization was held constant across repetitions. This effect was significant at 42-63 ms within three clusters on the right temporo-frontal region; and at 165-215 ms in a large cluster on the left temporo-parietal convexity. Our results reveal two varieties of representations of sound objects within the ventral/What stream: one location-independent, as initially postulated in the dual-stream model, and the other location-linked.

Cities, skills, and regional change

One approach to urban areas emphasizes the existence of certain immutable relationships, such as Zipf's or Gibrat's Law. An alternative view is that urban changereflects individual responses to changing tastes or technologies. This paper examinesalmost 200 years of regional change in the U.S. and finds that few, if any, growth relationships remain constant, including Gibrat's Law. Education does a reasonable jobof explaining urban resilience in recent decades, but does not seem to predict countygrowth a century ago. After reviewing this evidence, we present and estimate a simple model of regional change, where education increases the level of entrepreneurship.Human capital spillovers occur at the city level because skilled workers produce moreproduct varieties and thereby increase labor demand. We find that skills are associatedwith growth in productivity or entrepreneurship, not with growth in quality of life, atleast outside of the West. We also find that skills seem to have depressed housing supplygrowth in the West, but not in other regions, which supports the view that educatedresidents in that region have fought for tougher land-use controls. We also present evidence that skills have had a disproportionately large impact on unemployment duringthe current recession.

On the bicanonical map of irregular varieties

From the point of view of uniform bounds for the birationality of pluricanonical maps, irregular varieties of general type and maximal Albanese dimension behave similarly to curves. In fact Chen-Hacon showed that, at least when their holomorphic Euler characteristic is positive, the tricanonical map of such varieties is always birational. In this paper we study the bicanonical map. We consider the natural subclass of varieties of maximal Albanese dimension formed by primitive varieties of Albanese general type. We prove that the only such varieties with non-birational bicanonical map are the natural higher-dimensional generalization to this context of curves of genus $2$: varieties birationally equivalent to the theta-divisor of an indecomposable principally polarized abelian variety. The proof is based on the (generalized) Fourier-Mukai transform.

Input diffusion and the evolution of production networks

What determines which inputs are initially considered and eventually adopted in the productionof new or improved goods? Why are some inputs much more prominent than others? We modelthe evolution of input linkages as a process where new producers first search for potentially usefulinputs and then decide which ones to adopt. A new product initially draws a set of 'essentialsuppliers'. The search stage is then confined to the network neighborhood of the latter, i.e., to theinputs used by the essential suppliers. The adoption decision is driven by a tradeoff between thebenefits accruing from input variety and the costs of input adoption. This has important implicationsfor the number of forward linkages that a product (input variety) develops over time. Inputdiffusion is fostered by network centrality ? an input that is initially represented in many networkneighborhoods is subsequently more likely to be adopted. This mechanism also delivers a powerlaw distribution of forward linkages. Our predictions continue to hold when varieties are aggregatedinto sectors. We can thus test them, using detailed sectoral US input-output tables. We showthat initial network proximity of a sector in 1967 significantly increases the likelihood of adoptionthroughout the subsequent four decades. The same is true for rapid productivity growth in aninput-producing sector. Our empirical results highlight two conditions for new products to becomecentral nodes: initial network proximity to prospective adopters, and technological progress thatreduces their relative price. Semiconductors met both conditions.

Comparative study of the mandarin hybrid fruit characteristics: Nova, Murcott and Ortanique in Capão Bonito SP, Brazil

The Murcott tangor represent 20% of the tangerines trees in São Paulo State being the second more grown. Their fruits have good acceptance in the market cause of the good characteristics presented as: size, attractive internal and external color, transport resistance, high juice rate and industry potential. It is necessary to study the behavior of others varieties, in order to amplify the diversity of tangerine industry, which show suitable characteristics to the fresh fruit market and that make possible different harvest season. Many tangerine varieties, selected from the Citrus Germplasm Bank of the do Centro Avançado de Pesquisa Tecnológica do Agronegócio de Citros "Sylvio Moreira"/IAC, belong to trials carried out in 15 places in São Paulo State. The Capão Bonito area, south-west of the state, is one of this places where the Nova tangelo, the Ortanique and the Murcott tangors are showing quite good results about their fruit qualities. This paper had as an objective to compare the fruit characteristics of the Nova tangelo, the Murcott and the Ortanique tangors grafted on two rootstocks: Rangpur lime and Cleopatra mandarin. Accordingly to the gotten results, is possible to conclude that Nova and Ortanique had shown weight, width, fruit shape and juice percent, similar to the Murcott. In compliance with the harvest season, the Nova present suitable conditions to fresh fruit market in May and June. By the other hand the Murcott fruits can be harvested in July to August and the Ortanique in August to September. For this reason, is possible extend the harvest season of this mandarin-like, from two to five month, occurring inclusive in a period out of the crop at the north hemisphere.

Quadrant/octant sequencing and the role of coherent structures in bed load sediment entrainment

To permit the tracking of turbulent flow structures in an Eulerian frame from single-point measurements, we make use of a generalization of conventional two-dimensional quadrant analysis to three-dimensional octants. We characterize flow structures using the sequences of these octants and show how significance may be attached to particular sequences using statistical mull models. We analyze an example experiment and show how a particular dominant flow structure can be identified from the conditional probability of octant sequences. The frequency of this structure corresponds to the dominant peak in the velocity spectra and exerts a high proportion of the total shear stress. We link this structure explicitly to the propensity for sediment entrainment and show that greater insight into sediment entrainment can be obtained by disaggregating those octants that occur within the identified macroturbulence structure from those that do not. Hence, this work goes beyond critiques of Reynolds stress approaches to bed load entrainment that highlight the importance of outward interactions, to identifying and prioritizing the quadrants/octants that define particular flow structures. Key Points <list list-type=''bulleted'' id=''jgrf20196-list-0001''> <list-item id=''jgrf20196-li-0001''>A new method for analysing single point velocity data is presented <list-item id=''jgrf20196-li-0002''>Flow structures are identified by a sequence of flow states (termed octants) <list-item id=''jgrf20196-li-0003''>The identified structure exerts high stresses and causes bed-load entrainment

Review. Characterization and selection of hexaploid wheats containing resistance to Heterodera avenae or Mayetiola destructor introgressed from Aegilops

Cereal cyst nematode (CCN, Heterodera avenae) and Hessian fly (HF, Mayetiola destructor) are two major pests affecting wheat crops worldwide including important cereal areas of Spain. Aegilops ventricosa and Ae. triuncialis were used as donors in a strategy to introduce resistance genes (RG) for these pests in hexaploid wheat (Triticum aestivum L.). Two 42 chromosomes introgression lines have been derived from Ae. ventricosa: H-93-8 and H-93-33 carrying genes Cre2 and H27 conferring resistance to CCN and HF, respectively. Line TR-3531 with 42 chromosomes has been derived from Ae. triuncialis and carries RGs conferring resistance for CCN (Cre7) and for HF (H30). Alien material has been incorporated in lines H-93 by chromosomal substitution and recombination, while in line TR-3531 homoeologous recombination affecting small DNA fragments has played a major role. It has been demonstrated that Cre2, Cre7, H27 and H30 are major single dominant genes and not allelic of other previously described RGs. Biochemical and molecular-biology studies of the defense mechanism triggered by Cre2 and Cre7 have revealed specific induction of peroxidase and other antioxidant enzymes. In parallel to these basic studies advanced lines carrying resistance genes for CNN and/or HF have been developed. Selection was done using molecular markers for eventually «pyramiding» resistance genes. Several isozyme and RAPD markers have been described and, currently, new markers based on transposable elements and NBS-LRR sequences are being developed. At present, two advanced lines have already been included at the Spanish Catalogue of Commercial Plant Varieties.

Post-market environmental monitoring of Bt maize in Spain: Non-target effects of varieties derived from the event MON810 on predatory fauna

The Spanish Government has established post-market environmental monitoring (PMEM) as mandatory for genetically modified (GM) crop varieties cultivated in Spain. In order to comply with this regulation, effects of Bt maize varieties derived from the event MON810 on the predatory fauna were monitored for two years in northeast and central Spain. The study was carried out with a randomized block design in maize fields of 3-4 ha on which the abundance of plant-dwelling predators and the activity-density of soil-dwelling predators in Bt vs. non-Bt near-isogenic varieties were compared. To this end, the plots were sampled by visual inspection of a certain number of plants and pitfall traps 6 or 7 times throughout two seasons. No significant differences in predator densities on plants were found between Bt and non-Bt varieties. In the pitfall traps, significant differences between the two types of maize were found only in Staphylinidae, in which trap catches in non-Bt maize were higher than in Bt maize in central Spain. Based on the statistical power of the assays, surrogate arthropods for PMEM purposes are proposed; Orius spp. and Araneae for visual sampling and Carabidae, Araneae, and Staphylinidae for pitfall trapping. The other predator groups recorded in the study, Nabis sp. and Coccinellidae in visual sampling and Dermaptera in pitfall trapping, gave very poor power results. To help to establish a standardized protocol for PMEM of genetically modified crops, the effect-detecting capacity with a power of 0.8 of each predator group is given.

Anthocyanins, pigment stability and antioxidant activity in jabuticaba [Myrciaria cauliflora (Mart.) O. Berg]

Different solvents were evaluated for the extraction of jabuticaba anthocyanin pigments, identifying, quantifying and verifying the stability of the anthocyanins, as well as the conduction of three antioxidant activity assays and determination of the vitamin C levels. The maceration with ethanol acidified with HCl 1.5 mol L-1 (85:15) provides better pigment extraction and stability. The skin is anthocyanin rich, presenting 1.59 and 2.06 g 100 g-1 of dry matter in the Paulista and Sabará varieties, respectively. Cyanidin 3-glucoside is the majority pigment of the skins, followed by delphinidin 3-glucoside. The highest level of vitamin C was found in the skins and seeds of both varieties. It was verified that the skins, presented more antioxidant activity, in free radical capture, as well as in retarding the lipid oxidation process.

Breeding, genetic and genomic of citrus for disease resistance

Although the citriculture is one of the most important economic activities in Brazil, it is based on a small number of varieties. This fact has contributed for the vulnerability of the culture regarding the phytosanitary problems. A higher number of varieties/genotypes with potential for commercial growing, either for the industry or fresh market, has been one of the main objectives of citrus breeding programs. The genetic breeding of citrus has improved, in the last decades, due to the possibility of an association between biotechnological tools and classical methods of breeding. The use of molecular markers for early selection of zygotic seedlings from controlled crosses resulted in the possibility of selection of a high number of new combination and, as a consequence, the establishment of a great number of hybrids in field experiments. The faster new tools are incorporated in the program, the faster is possibility to reach new genotypes that can be tested as a new variety. Good traits should be kept or incorporate, whereas bad traits have to be excluded or minimized in the new genotype. Scion and rootstock can not be considered separately, and graft compatibility, fruit quality and productivity are essential traits to be evaluated in the last stages of the program. The mapping of QTLs has favored breeding programs of several perennial species and in citrus it was possible to map several characteristics with qualitative and quantitative inheritance. The existence of linkage maps and QTLs already mapped, the development of EST and BAC library and the sequencing of the Citrus complete genome altogether make very demanding and urgent the exploration of such data to launch a wider genetic study of citrus. The rising of information on genome of several organisms has opened new approaches looking for integration between breeding, genetic and genome. Genome assisted selection (GAS) involves more than gene or complete genome sequencing and is becoming an import support in breeding programs of annual and perennial species. An huge information amount can be derivate from genome analysis. The use and benefit of such informations will depend on the genetic basis of the breeding program.