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Goiânia, Brazil

Breseghello F.,Embrapa Arroz e Feijao | Coelho A.S.G.,Federal University of Goais
Journal of Agricultural and Food Chemistry | Year: 2013

Plant breeding can be broadly defined as alterations caused in plants as a result of their use by humans, ranging from unintentional changes resulting from the advent of agriculture to the application of molecular tools for precision breeding. The vast diversity of breeding methods can be simplified into three categories: (i) plant breeding based on observed variation by selection of plants based on natural variants appearing in nature or within traditional varieties; (ii) plant breeding based on controlled mating by selection of plants presenting recombination of desirable genes from different parents; and (iii) plant breeding based on monitored recombination by selection of specific genes or marker profiles, using molecular tools for tracking within-genome variation. The continuous application of traditional breeding methods in a given species could lead to the narrowing of the gene pool from which cultivars are drawn, rendering crops vulnerable to biotic and abiotic stresses and hampering future progress. Several methods have been devised for introducing exotic variation into elite germplasm without undesirable effects. Cases in rice are given to illustrate the potential and limitations of different breeding approaches. © 2013 American Chemical Society. Source

Aragao F.J.L.,Embrapa Recursos Geneticos e Biotecnologia | Nogueira E.O.P.L.,Embrapa Recursos Geneticos e Biotecnologia | Tinoco M.L.P.,Embrapa Recursos Geneticos e Biotecnologia | Faria J.C.,Embrapa Arroz e Feijao
Journal of Biotechnology | Year: 2013

Golden mosaic of common bean is caused by the Bean golden mosaic virus (BGMV). The disease is one of the greatest constraints on bean production in Latin America and causes significant yield losses. The RNAi concept was explored to silence the rep (AC1) viral gene and a transgenic bean line immune to BGMV upon inoculation at high pressure was previously generated. Identification of the transgene insert confirmed the presence of a single locus corresponding to two intact copies of the RNAi cassette in opposite orientation and three intact copies of the AtAhas gene. It is flanked by Phaseolus genomic sequences and interspersed by one nuclear and three chloroplastic genomic sequences. Southern analyses showed that the transgenes were structurally stable for eight self-pollinated generations and after backcrosses with a non transgenic commercial variety. Transgene expression analyses revealed similar levels of siRNA in leaves of transgenic plants cultivated under field conditions in three distinct regions. siRNA were also analyzed during seed development in common bean transgenic plants. siRNA signals were also detected in seeds, albeit at significantly lower levels than those observed in leaves, and could not be detected in seeds cooked during 10. min. This information is relevant to demonstrate that GM beans are free of siRNA signals after cooking and therefore suitable for human consumption. Additionally, characterization of the locus where the transgene was integrated in the common bean genome provides a valuable tool to trace this GM bean material in the field and in the market. © 2013 Elsevier B.V. Source

Petter F.A.,Federal University of Piaui | Madari B.E.,Embrapa Arroz e Feijao
Revista Brasileira de Engenharia Agricola e Ambiental | Year: 2012

Due to the high activity of microorganisms, the loss of soil organic matter is high in tropical regions. This loss becomes even greater if the soil is managed improperly or when there is no technology that leverages the permanence of the soil carbon by maintaining appropriate levels of organic matter, providing chemical, physical and biological soil improvements and contributing to reduce CO2 emissions to the atmosphere. Due to its aromatic structure, biochar is a highly stable form of carbon in the soil that may contribute to the reduction of greenhouse gas emissions, such as CO2, N2O and CH4, and act as a soil conditioner, improving the physical and chemical properties of the soil. Biochar may also result in increased productivity due to the improvement of soil attributes or a possible electrophysiological effect. Research over the past decades has demonstrated the potential of biochar as a soil conditioner, improving fertility and nutrient-use efficiency, in addition to maximising the productivity of crops, such as soybean and rice. Source

Andrade R.S.,ALC n. 14 | Stone L.F.,Embrapa Arroz e Feijao
Revista Brasileira de Engenharia Agricola e Ambiental | Year: 2011

The objective of this study was to estimate the soil moisture at field capacity (θfc) by an equation based on the soil water retention curve (SWRC) and by correlation with physico-hydrical attributes and data from texture and organic matter for very clayey, clayey, loamy, and sandy soils. The study was carried out with 2242 samples from 'Cerrado' soils, which contained information on textural classification, physical attributes and soil water retention. For 745 samples, there was information on the saturated hydraulic conductivity (Ko) and for 472, on clay, silt, sand and organic matter contents. For samples with measured Ko, θfc was determined based on parameters of the equation of Genuchten (1980), assuming that the drainage rate (τ) is a percentage p of Ko. p values of 0.0025, 0.0050, 0.0100, 0.0150, and 0.0200 were considered. It was observed that θfc can be estimated by the equation based on SWRC, considering τ as 1% of the Ko value. θfc can also be estimated as a function of moisture at the inflection point of SWRC and soil porosity for each soil horizon. The soil water tension corresponding to θfc was between 6.5 and 7.5 kPa, for τ equivalent to 1% of the Ko value. Source

Faria J.C.,Embrapa Arroz e Feijao
GM crops | Year: 2010

Gene flow is a common phenomenon even in self-pollinated plant species. With the advent of genetically modified plants this subject has become of the utmost importance due to the need for controlling the spread of transgenes. This study was conducted to determine the occurrence and intensity of outcrossing in transgenic common beans. In order to evaluate the outcross rates, four experiments were conducted in Santo Antonio de Goiás (GO, Brazil) and one in Londrina (PR, Brazil), using transgenic cultivars resistant to the herbicide glufosinate ammonium and their conventional counterparts as recipients of the transgene. Experiments with cv. Olathe Pinto and the transgenic line Olathe M1/4 were conducted in a completely randomized design with ten replications for three years in one location, whereas the experiments with cv. Pérola and the transgenic line Pérola M1/4 were conducted at two locations for one year, with the transgenic cultivar surrounded on all sides by the conventional counterpart. The outcross occurred at a negligible rate of 0.00741% in cv. Pérola, while none was observed (0.0%) in cv. Olathe Pinto. The frequency of gene flow was cultivar dependent and most of the observed outcross was within 2.5 m from the edge of the pollen source. Index terms: Phaseolus vulgaris, outcross, glufosinate ammonium. Source

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