5 research outputs found
OcorrĂȘncia de fungos endofĂticos "dark septate" em raĂzes de Oryza glumaepatula na AmazĂŽnia
O objetivo deste trabalho foi avaliar a ocorrĂȘncia de fungos endofĂticos "dark septate" (DSEF) em Oryza glumaepatula, na AmazĂŽnia, e sua capacidade de colonização in vitro. Foram coletadas plantas de O. glumaepatula em ĂĄrea de cerrado e de mata em Roraima. As raĂzes foram tratadas para a observação de hifas melanizadas septadas e de microesclerĂłdios. Os fungos foram isolados em meio ĂĄgar malte. Os DSEF foram observados em plantas coletadas em ambos os ambientes, com maior colonização nas coletadas da mata. Um isolado foi capaz de colonizar o hospedeiro original e tambĂ©m plantas de Oryza sativa, exibindo as estruturas caracterĂsticas de DSEF em plantas de arroz saudĂĄveis
Development of arbuscular mycorrhizal fungi in the presence of different patterns of Trifolium repens shoot flavonoids
We tested the effects of the flavonoid 3-methoxi-5,6,7,8-hydroxy-4'hydroxy flavone (NMHTV) isolated from shoots of non arbuscular mycorrhizal (AM) inoculated clover, and of the flavonoids 5,6,7,8-hydroxy-3-methoxy flavone (MH-1); 5,6,7,8-hydroxy-4'- hydroxy flavone (MH-2); and 5,7-hydroxy-3,4'-methoxy flavone (MH-3); isolated from AM clover (Trifolium repens) shoots, on spore germination, hyphal length, hyphal branches and the number of cluster of auxiliary cells or the number of secondary spores (Presymbiotic stage) and on the number of entry points and the percentage of AM colonized root of tomato (Lycopersicum esculentum) by the AM fungi Gigaspora rosea, Giaspora margarita, Glomus mosseae and Glomus intraradices (Symbiotic stage). Non significant effects of the flavonoids isolated from the shoot of mycorrhizal colonized clover on the presymbiotic and symbiotic stages of Gigaspora and Glomus endophytes were found. The flavonoid NMHTV isolated from non AM clover shoot, did not affect the percentage of germination of spores but significantly increased (P < 0.05) the other steps of the presymbiotic stage of Gi. margarita spores when 2 ÎŒM concentration was used. The symbiotic stage of Gi. margarita was also significantly increased when 2 ÎŒM of the flavonoid NMHTV was applied. This flavonoid had no effect on the presymbiotic development of G. mosseae, G. intraradices and Gi. rosea except when 8 ÎŒM concentration was used, which inhibited the hyphal length of Gi. rosea. These results suggest the possible implication of the flavonoid NMHTV in the susceptibility of tomato roots to the AM formation by Gi. margarita. The absence of stimulation of the AM presymbiotic and symbiotic stages in tomato by exogenous application of the newly synthesized flavonoids MH-1, MH-2, and MH-3, in clover shoots after AM colonization, indicated that the autorregulation of the AM symbiosis can be, at least partially, due to the disappearance of flavonoids in AM colonized plants that stimulated the AM symbiosis.Fil:Scervino, J.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Ponce, M.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Godeas, A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
Flavonoids exclusively present in mycorrhizal roots of white clover exhibit a different effect on arbuscular mycorrhizal fungi than flavonoids exclusively present in non-mycorrhizal roots of white clover
The flavonoids 5,6,7,8,9-hydroxy chalcone, 3,7-hydroxy-4âČmethoxy flavone, 5,6,7,8-hydroxy-4âČ-methoxy flavone and 3,5,6,7,4âČ-hydroxy flavone can be detected only in non-mycorrhizal roots of white clover, but not in mycorrhizal roots, whereas the flavonoids acacetin, quercetin and rhamnetin are only present in mycorrhizal roots. We tested the effect of several concentrations of these compounds on spore germination, hyphal growth, hyphal branching, formation of clusters of auxiliary cells and of secondary spores of the arbuscular mycorrhizal fungi Gigaspora rosea, Gigaspora margarita, Glomus mosseae and Glomus intraradices. Our results indicate that depending on the flavonoid, the tested compounds are involved at different stages in the regulation of mycorrhization. This hypothesis is strengthened by their differing effect on several AM fungal growth parameters. Furthermore, our study provides more data on the AM fungus genus/species specificity of flavonoids. © 2005 Taylor & Francis.Fil:Scervino, J.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Ponce, M.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Godeas, A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
Exudates of dark septate endophyte (DSE) modulate the development of the arbuscular mycorrhizal fungus (AMF) Gigaspora rosea
Exudates of a dark septate endophyte (DSE) identified as Dreschlera sp., a common endophyte isolated by the inner cortical cells of the grass Lolium multiflorum, were put in contact with the arbuscular mycorrhizal fungus (AMF) Gigaspora rosea. These exudates stimulated the hyphal length and the hyphal branching of the AMF. A negative effect on the extramatrical phase of the AMF was detected. This is the first report to show how exudates of DSE can affect the development of AMF. These results show that DSE could be modifying the mycorrhizal status of the plants, modulating a different symbiosis in the rhizosphere.Fil: Scervino, J.M.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y BiologĂa Experimental; ArgentinaFil: Gottlieb, A.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y BiologĂa Experimental; ArgentinaFil: Silvani, V.A.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y BiologĂa Experimental; ArgentinaFil: PĂ©rgola, M.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y BiologĂa Experimental; ArgentinaFil: FernĂĄndez, L.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y BiologĂa Experimental; ArgentinaFil: Godeas, Alicia Margarita. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y BiologĂa Experimental; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de Biodiversidad y BiologĂa Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y BiologĂa Experimental y Aplicada; Argentin