Reference gene selection for quantitative reverse transcription-polymerase chais reaction normalization during in vitro adventitious rooting in Eucaliptus globulus Labill

Background: Eucalyptus globulus and its hybrids are very important for the cellulose and paper industry mainly due to their low lignin content and frost resistance. However, rooting of cuttings of this species is recalcitrant and exogenous auxin application is often necessary for good root development. To date one of the most accurate methods available for gene expression analysis is quantitative reverse transcription-polymerase chain reaction (qPCR); however, reliable use of this technique requires reference genes for normalization. There is no single reference gene that can be regarded as universal for all experiments and biological materials. Thus, the identification of reliable reference genes must be done for every species and experimental approach. The present study aimed at identifying suitable control genes for normalization of gene expression associated with adventitious rooting in E. globulus microcuttings. Results: By the use of two distinct algorithms, geNorm and NormFinder, we have assessed gene expression stability of eleven candidate reference genes in E. globulus: 18S, ACT2, EF2, EUC12, H2B, IDH, SAND, TIP41, TUA, UBI and 33380. The candidate reference genes were evaluated in microccuttings rooted in vitro, in presence or absence of auxin, along six time-points spanning the process of adventitious rooting. Overall, the stability profiles of these genes determined with each one of the algorithms were very similar. Slight differences were observed in the most stable pair of genes indicated by each program: IDH and SAND for geNorm, and H2B and TUA for NormFinder. Both programs indentified UBI and 18S as the most variable genes. To validate these results and select the most suitable reference genes, the expression profile of the ARGONAUTE1 gene was evaluated in relation to the most stable candidate genes indicated by each algorithm. Conclusion: Our study showed that expression stability varied between putative reference genes tested in E. globulus. Based on the AGO1 relative expression profile obtained using the genes suggested by the algorithms, H2B and TUA were considered as the most suitable reference genes for expression studies in E. globulus adventitious rooting. UBI and 18S were unsuitable for use as controls in qPCR related to this process. These findings will enable more accurate and reliable normalization of qPCR results for gene expression studies in this economically important woody plant, particularly related to rooting and clonal propagation

Implications of the agricultural frontier occupation model for family farming in Terra Nova do Norte and Nova Guarita, Mato Grosso, Brazilian Amazon

Este estudo objetiva compreender as dificuldades geradas pelo modelo de ocupação de uma fronteira agrícola da Amazônia brasileira e as estratégias usadas pelos agricultores familiares para superá-las. Os dados foram coletados por meio da realização de 20 grupos focais, associados à construção de linhas do tempo. Os desafios enfrentados pelos agricultores, durante a fase de ocupação agrícola do território, são similares aos vividos pelos milhares de brasileiros que migraram para a Amazônia em busca de terra e da reprodução social de suas famílias na agricultura. A exceção está na ocupação ilegítima de uma área de reserva legal coletiva, a qual gera restrições de acesso ao crédito rural, dadas as irregularidades fundiária e ambiental. Novas iniciativas de desenvolvimento emergem dos aprendizados assimilados durante as fases de crise e de reestabelecimento do setor da agricultura familiar na região.This study aims to understand the difficulties generated by the occupation model of an agricultural frontier in the Brazilian Amazon and the strategies used by family farmers to overcome them. The data were collected through 20 focus groups, associated with the construction of timelines. The challenges faced by farmers during the phase of agricultural occupation of the territory are similar to those experienced by the thousands of Brazilians who migrated to the Amazon in search of land and the social reproduction of their families in agriculture. The exception is the illegitimate occupation of a collective legal reserve area, which generates restrictions on access to rural credit, given land and environmental irregularities. New development initiatives emerge from the lessons learned during the crisis and the reestablishment of the family farming sector in the region

Boletín del Servicio Meteorológico Nacional: Epoca 2ª Año XIII Número 131 - 1964 Mayo 10

O Brasil é um dos maiores produtores de polpa de eucalipto e suas plantações são dependentes do enraizamento adventício de genótipos selecionados. Neste trabalho foram analisados os efeitos de diferentes fontes de carboidratos e de qualidade de luz no enraizamento adventício in vitro de duas espécies de eucalipto economicamente importantes, Eucalyptus grandis, de fácil enraizamento e Eucalyptus globulus, recalcitrante ao enraizamento. As fontes de carboidratos testadas em meio de cultura líquido foram sacarose, glicose e frutose. Microestacas de ambas as espécies e plantas-matrizes de Eucalyptus globulus foram expostas a comprimentos de onda enriquecidos para luz branca, azul, vermelha e vermelho-extrema e seus efeitos foram testados em relação ao enraizamento. O enraizamento adventício aumentou em ambas as espécies quando foi fornecida sacarose durante a fase de indução e frutose na fase de formação. Fazendo uma analogia entre o enraizamento adventício e a tuberização de batata, este resultado pode ser atribuído a atividade de invertases na fase de indução e fructoquinase na fase de formação, porém mais estudos devem ser conduzidos para confirmar esta hipótese. Não houve efeito de qualidade de luz no enraizamento adventício quando os tratamentos de luz foram aplicados nas microestacas. A exposição de plantas-matrizes crescidas em meio de cultura sem sacarose à ambiente enriquecido com comprimento de onda vermelho-extremo proporcionou um aumento de 255% na porcentagem de enraizamento de suas microestacas, mesmo na ausência de auxina exógena no meio de enraizamento, quando comparado com plantas-matrizes expostas à luz branca nas mesmas condições de cultura. Este resultado está aparentemente relacionado com o balanço 8 endógeno de açúcares solúveis e amido na parte aérea e raízes em desenvolvimento, com maior conteúdo de ambos na região das raízes.Brazil is one of the largest producers of eucalypt pulp and its plantations are dependent of adventitious rooting of selected genotypes. In this work we analyzed the effects of different carbohydrate sources and light qualities on in vitro adventitious rooting of two economically important eucalypt species, the easy-to-root Eucalyptus grandis and the recalcitrant Eucalyptus globulus. The carbohydrate sources tested in static liquid medium were sucrose, glucose and fructose. The effect of white, blue, red and far-red light exposure on microcuttings of both species and on donor-plants of E. globulus was evaluated in relation to rooting. Rooting was improved in both species by supplying sucrose in the induction phase and fructose in the formation phase. By a putative analogy of adventitious rooting with tuberization in potato stems, this result was attributed to activities of invertases in the induction phase and fructokinase in the formation phase, but more studies will be needed to confirm this hypothesis. There was no effect of light quality on adventitious rooting when light treatments were applied on microcuttings. Compared to the white light-treated control donor-plants grown on medium without sucrose, donor-plants grown under a far-red light enriched environment on medium devoid of sucrose yielded 255% in the rooting percentage of microcuttings derived therefrom, even in the absence of exogenous auxin in rooting medium. This result was apparently related to the balance between endogenous hexoses and starch content in shoots and developing roots, with a higher content of both in the rooting zone

Efeito de qualidade de luz e disponibilidade de sacarose em microcepas na rizogênese adventícia de Eucalyptus globulus Labill

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O uso de uréia e nitrato como fontes de nitrogênio e seus efeitos no enraizamento adventício de Eucalyptus Globulus

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O uso de uréia e nitrato como fontes de nitrogênio e seus efeitos no enraizamento adventício de Eucalyptus Globulus

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Efeito de fontes de nitrogênio no desenvolvimento e ramificação de raízes adventícias de Eucalyptus globulus

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Efeito de fontes de nitrogênio no desenvolvimento e ramificação de raízes adventícias de Eucalyptus globulus

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