Juliana Martins Ribeiro

Influence of NaClO on nutrient medium sterilization and on pineapple (Ananas comosus cv Smooth cayenne) behavior

A new protocol for the preparation and sterilization of media with sodium hypochlorite was tested for in vitro culturing of pineapple shoots. Total active chlorine concentrations equal to or higher than 0.0003%, as well as other asepsis procedures, provided complete sterilization of the medium. At a total active chlorine concentration of 0.0003%, pineapple shoots more than doubled both their biomass and the number of new shoots.

Utilização de hipoclorito de sódio na esterilização de meio de cultura para multiplicação in vitro de Eucalyptus pellita L.

Lately it has been observed a great interest in the research area of plant tissue culture in discovering new alternatives leading to cost reduction of the plants produced in commercial laboratories, in order to turn this alternative of plant propagation more economical. A potentially promising alternative for this reduction of costs, but which has not been receiving the due attention, is the possibility of substituting the autoclaving technique to a more economical one. With this purpose, two tests were carried out, using a new protocol of medium preparation, which consisted of the chemical sterilization of all the utensils used in the preparation and packaging of the culture medium as well, associated to the addition of the sterilizing agent to the medium, in different concentrations. The objective of the first test was to observe the influence of different concentrations of NaClO added to the culture medium, on its sterilization. The second test aimed at verifying the reaction of the Eucalyptus pellita tissues to different concentrations of NaClO in the culture medium. The addition of NaClO to the culture medium, equal or higher than 0.0005% in the fist test and of 0.005% in the second one, allowed complete sterilization of the medium, without observing any damage to the Eucalyptus pellita tissues, even when they were grown on culture medium containing up to 0.009%, the maximum concentration tried. The results showed the viability of eliminating the autoclave for the sterilization of culture media.

Substituição de nitrato de potássio (PA) por salitre potássico no preparo de meio de cultura de tecidos vegetais esterilizado com hipoclorito de sódio

A aquisicao de nitrato de potassio PA, para qualquer finalidade, depende de autorizacao do Ministerio da Defesa, o que resulta em dificuldades na sua aquisicao. Com a finalidade de estudar a possibilidade da substituicao desse reagente por outro produto encontrado livremente no comercio, foi conduzido um experimento onde se testaram varias concentracoes de salitre potassico em comparacao com o nitrato de potassio PA, como componente dos sais de MS. Utilizou-se o produto granulado MURER® nas seguintes concentracoes (g L-1): a) 7,0; b) 7,4; c) 7,8; d) 8,2. Foi adicionado um tratamento-controle, com o KNO3 PA, conforme aparece nos sais de MS (1,9 g L-1), sendo a especie testada a fafia, a partir de segmentos nodais. O meio de cultura constituiu-se dos sais de MS, vitaminas de White, 30 g L-1 sacarose, 2,0 mg L-1 acido indol butirico, 2,0 mg L-1 acido naftalenoacetico, 2,0 mg L-1 benzilaminopurina, pH 6,0 + 0,1 e 1,5 g L-1 Phytagel® como gelificante. O numero medio de ramos formados para todos os tratamentos foi inferior ao do tratamento-controle; mas, em compensacao, o comprimento medio deles foi superior, tambem em todos os tratamentos, sendo que o comprimento total de ramos na menor concentracao de salitre, atingiu 17,0 cm, enquanto no tratamento-controle foi de 12,6 cm. A media da biomassa seca foi de 68,3 mg para a menor concentracao de salitre e de 50,0 mg para o tratamento-controle. A analise dos resultados indicou ser vantajosa a substituicao do nitrato de potassio PA pelo salitre potassico.

Efeito do melado de cana-de-açúcar no desenvolvimento in vitro de bananeira (Musa spp.) cv. Maçã

Apesar de oferecer uma serie de vantagens, quanto a qualidade do produto final, a tecnica de cultivo in vitro de plantas ainda e considerada dispendiosa, por causa, dentre outros fatores, da utilizacao de reagentes com alto grau de pureza no preparo de meios nutritivos. Entre as alternativas que podem ser adotadas para a reducao dos custos relacionados com a producao de mudas, apresenta potencial a substituicao de produtos PA por aqueles de menor custo. Baseado nestas informacoes, o objetivo deste estudo foi avaliar o efeito do melado de cana-de-acucar sobre o desenvolvimento in vitro de bananeira, cv. Maca. Para tal proposito, plantas de bananeira foram inoculadas em meios nutritivos, formulados a base de melado de cana-de-acucar, com quatro concentracoes distintas (brix de 1,5; 3,0; 4,5 e 6,0), e os dados obtidos foram comparados com aqueles das plantas cultivadas em meio MS (controle), perfazendo um total de cinco tratamentos. Apesar de terem-se desenvolvido em todos os tratamentos testados, observou-se que, para as variaveis numero medio de folhas e biomassa da materia fresca, as plantas cultivadas no meio MS (controle) apresentaram valores superiores. Entretanto, para o numero medio de raizes, nao houve diferenca estatistica entre os tratamentos utilizados. O melado de cana-de-acucar nao favorece o desenvolvimento de plântulas de bananeira, mas pode ser utilizado para o enraizamento dessas plantas in vitro.

Penetration, development, and reproduction of Meloidogyne enterolobii on Psidium species and induced cellular responses in the roots.

Meloidogyne enterolobii has severely compromised the main guava producing regions in Brazil, thereby stimulating the development of resistant varieties for efficient management of this nematode. This study aimed to assess the penetration, development, reproduction, and induced cellular responses of M. enterolobii in roots of four species of the genus Psidium (P. guajava ?Paluma?, P. guineense, P. cattleyanum, and P. friedrichstalianum) from the Active Germplasm Bank (BAG) of the Center for Agricultural Research of the Semi-arid Tropics (Embrapa Semi-arid) located in Petrolina, PE, Brazil. Three experiments were carried out to assess the penetration, development, and reproduction of the nematode and, subsequently, histological analyses were performed. Nematode penetrated indistinctly in both resistant and susceptible species, but only in ?Paluma? an evolution was observed from vermiform juveniles to ?sausage? and globose forms in experiment 1. In experiment 2, all species presented ?sausage? forms of nematode, but only in ?Paluma?, these forms reached adult female stages. In experiment 3, only ?Paluma? was susceptible to M. enterolobii, with reproduction factor above unity. Histological analyses showed that, except for P. guajava, the other Psidium species presented poorly developed feeding sites at 20 days after inoculation.

Reproduction of the guava root-knot nematode in Psidium accesses

The guava decline, a complex disease caused by the interaction between Meloidogyne enterolobii and Fusarium solani, has caused damage to production and unviable guava producing areas in the Lower Basin of the Sao Francisco Valley. The management of this disease is difficult due to the facts that cultivated plants are susceptible to nematodes, nematicides have no effective control, and the use of fungicides to control Fusarium still has not been evaluated. However, some Psidium genotypes, such as the aracazeiros, show resistance to the nematodes, and therefore decline resistance. The objective of this study was to evaluate the interaction between genotypes of Psidium spp. and M. enterolobii to identify resistant plants. Three aracazeiro genotypes from the states of Sao Paulo and Parana were artificially inoculated with M. enterolobii and compared with the species P. guajava cultivar Paluma, which is a commercial cultivar susceptible to root-knot nematode. All aracazeiro genotypes evaluated were resistant to the disease, with low reproduction factor (0.000 to 0.004) compared to cultivar Paluma (FR = 1,610). These results demonstrate that the aracazeiro genotypes have the potential to be used in the development of rootstocks resistant to guava decline.

Efeito de extratos proteicos de amendoim sobre o desenvolvimento, a capacidade infectiva e atividade de enzimas proteolíticas de Meloidogyne enterolobii

No Brasil, Meloidogyne enterolobii vem causando perdas significativas na producao de goiabeiras e, no submedio do Vale do Sao Francisco, por exemplo, o impacto negativo decorrente da infeccao e morte de goiabeiras tem refletido diretamente na qualidade de vida dos agricultores. Ate o momento, nao existem metodos de controle efetivos: os nematicidas avaliados experimentalmente nao tem sido eficientes e nao ha produtos registrados no Ministerio da Agricultura, Pecuaria e Abastecimento para aplicacao em goiabeiras. Assim, ha necessidade de realizar pesquisa basica nesta area. A prospeccao de proteinas relacionadas com a resistencia em especies resistentes pode ser uma alternativa para o desenvolvimento de medidas para seu controle. Para isso, foram realizados ensaios biologicos de toxicidade para a analise do efeito de extratos proteicos de amendoim sobre o desenvolvimento, a capacidade infectiva e atividade de enzimas proteoliticas de M. enterolobii visando a identificacao de proteinas com potencial para controle desse nematoide. Os resultados obtidos indicaram que o extrato proteico total de amostras de raizes de plantas de amendoim inoculadas nao tem efeito sobre as tres caracteristicas supracitadas. Sendo assim, sao necessarios estudos dessa natureza com outras especies resistentes ao patogeno visando a identificacao de proteinas que apresentem potencial para o seu controle.

Uso da rapadura como meio nutritivo para cultivo in vitro de bananeira cv. Maçã

Use of panela as nutritive medium for in vitro culture of banana cv. Maca The purpose of this study was to evaluate the effect of panela (hard brown sugar) on in vitro development of banana cv. Maca, in order to reduce production costs. Banana explants were inoculated in nutrient media formulated with four different concentrations of panela solution (10, 25, 50 and 75%) and data were compared with those of plants grown on MS medium (control), totalizing five treatments. After 60 days, the average number of leaves, shoots and roots, as well as the mean number of explants dead and oxidized were analyzed. There was no significant difference between treatments for most parameters, except for the mean number of oxidized explants, which was higher in the treatment containing 75% of panela. It was concluded that nutrient media with up to 50% of panela in the composition, without plant growth regulators, can be used for in vitro banana replacing the MS media.