Programa de Pós-graduação em Agronomia

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Navegando Programa de Pós-graduação em Agronomia por Por Orientador "Araújo, Leila Garcês de"

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    Bioprospecção de moléculas bioativas e antagonismo entre waitea circinata warcup & talbot e patógenos do arroz
    (Universidade Federal de Goiás, 2016-07-08) Carvalho, Jacqueline Campos Borba de; Filippi, Marta Cristina Corsi de; http://lattes.cnpq.br/0029536556461484; Araújo, Leila Garcês de; http://lattes.cnpq.br/3488880262260757; Araújo, Leila Garcês de; Silva, Gisele Barata da; Pasqualatto, Vanessa Gisele; Martins, Samuel Julio; Gonçalves, Fábio José
    Rice is one of the most important cereal in the world, but its productivity is affected by fungal diseases such as blast, brown spot, scald, sheath rot, sheath blight and stain of the sheath. Mycorrhizal fungi are capable of producing secondary metabolites that can be used to control pathogens. This study aimed to evaluate the potential of isolated mycorrhizal and their secondary metabolites in antagonism to the rice pathogens. The isolate mycorrhizal was characterized biochemically (cell wall and co - cultivation). We evaluated the mycorrhizal mycelia efficiency as well as their extracts and compounds in the inhibition of the mycelial growth, spore germination and formation of appressorium Magnaporthe oryzae. The efficiency of the pairing of volatile and non - volatile metabolites, and the efficiency of mycelium of Waitea circinata to other rice pathogens it was conducted in two trials. Four extracts of W. circinata (crude, mycelial, lyophilized and mycelial mass) were obtained and used in in vitro assays with pathogens. The tests for the suppression of leaf blast were also conducted in the greenhouse with the mycelium, extracts and mycorrhiza compounds. The completely randomized design was used for all tests. W. circinata produces Indolacetic Acid in vitro and showed enzymatic activity of glucanase, chitinase and protease when in cultivation with wall of the pathogens and co -cultivation. The mycorrhizal mycelia inhibited the mycelial growth of all rice pathogens in vitro. The isolated mycorrhizal was efficient in vitro production of volatile and non- volatile metabolites reducing mycelial growth of Sarocladium oryzae 94.41% and 53%, respectively. The mycelium of mycorrhiza to the concentration 10 g / L reduced the growth of M. oryzae by 97.92 % and has been effective and active even after autoclaving reducing the area of the colony by 93.53%, 77.30%, 31.07% and 4.42 % of Cochliobolus miyabeanus , Monographella albescens and Rhizoctonia oryzae - Ro93 and Ro88, respectively. In greenhouse the mycelium of mycorrhiza (10g/L En07 + M.o.) suppressed leaf blast at 83.89 %. Non- volatile metabolites of W. circinata inhibited in 48.95 % growth of M. oryzae. The analysis of spectrometric high resolution mass (HRMS) showed that the extract from the mycelial mass (MME), crude extract (CE) and lyophilized extract (LE) had the same chemical profile that can be attributed to sphinganine. The MME ( 700 / mL ) at 24 hours after installation of the test reduced the formation of appressorium of M. oryzae in 75.71 %, respectively. In the greenhouse, MME + M.o. suppressed the severity of leaf blast in 77.01 % and reduced AUDPC by 92.38 %. The results of this study indicate that the MME W. circinata is promising in biocontrol of the rice diseases.
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    Supressão de brusone nas folhas de arroz com Cladosporium cladosporioides.
    (Universidade Federal de Goiás, 2014-02-21) Chaibub, Amanda Abdallah; Filippi, Marta Cristina Corsi de; http://lattes.cnpq.br/0029536556461484; Araújo, Leila Garcês de;  http://lattes.cnpq.br/3488880262260757; Araújo, Leila Garcês de; Filippi, Marta Cristina Corsi de; Faria, Fabrícia Paula de; Vieira, Bernardo de Almeida Halfeld
    Rice blast (Magnaporthe oryzae Couch, anamorph-Pyricularia oryzae Cav.) is the major disease of rice causing yield losses up to 100%, in the world. Its control, currently held by integrating genetic resistance, cultural practices and chemical control, requires the inclusion of biological agents. The objectives of this study were to evaluate the in vitro antagonism between C. cladosporioides and four different rice pathogens; to verify the ability of C. cladosporioides in suppressing leaf blast and to study the mechanisms involved during disease suppression. The bioassays were conducted in a completely randomized design with three replications. The antagonism in vitro was evaluated by pairing-up, in Petri dishes containing PDA medium, nine different isolates of C. cladosporioides with the rice pathogens Sarocladium oryzae (sheath rot), Monographella albescens (scald), Cochliobolus miyabeanus (brown stain) and M. oryzae. All C. cladosporioides isolates reduced colonies mycelia growth up to 53.84% in addition to hallo formation. Among the nine tested isolates, four were selected for in vivo studies. Under controlled greenhouse conditions, three different concentrations were tested, in two different applications way; 1) 48 hours before challenger inoculation with M. oryzae; 2) mixture of M. oryzae and C. cladosporioides conidia suspensions. The isolated C24 C. cladosporioides (5x105) sprayed 48 hours, before challenger inoculation reduced 97.1% of leaf blast severity, and the spray mixture of conidial suspensions of C24 C. cladosporioides (5x101) and M. oryzae 3x105 spray of decreased leaf blast severity by 88.6%. Subsequently, the mechanisms involved in leaf blast suppression were investigated by using the same isolate, both applications methods and by collecting rice plants leaves sprayed with C. cladosporioides and M. oryzae. The application of C. cladosporioides 48 hours before challenger inoculation with M. oryzae and the conidial suspensions of mixture of M. oryzae and C. cladosporioides reduced to 83.9% and 78.6% of leaf blast severity, respectively. It was detected that, in the presence of C. cladosporioides and absence of the pathogen activity of enzymes GLU, LIPOX, PAL and POX increased significantly. In the presence of, C. cladosporioides and M. oryzae, POX and PAL activity and AS content also significantly increased, in both application forms. Scanning electron microscopy confirmed the physical interaction between plant/biological agent/pathogen during the penetration phase. It was proved that C. cladosporioides is a biological agent efficient in activating biochemical defense mechanisms of the rice plant during leaf blast suppression.