Caracterização morfológica de fungos para a germinação in vitro de sementes de Cyrtopodium saintlegerianum Rchb. f. e Epidendrum nocturnum Jacq.(Orchidaceae), ocorrentes no bioma cerrado
Nenhuma Miniatura disponível
Data
2012-06-28
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Federal de Goiás
Resumo
In Brazil, 2500 to 3000 species of orchids have been reported to occur, of
which 300 are found in the “cerrado” region. The orchids Cyrtopodium
saintlegerianum (epiphyte) and Epidendrum nocturnum (rupicola) occur in
areas anthropized of cerrado and cerrado rupestre, respectively. The orchids
posses mycorrhizal association with rhizoctonia-like and endophytic fungi. The
identification of these fungi can be done by microscopic and morphological
characters. Root infecting fungi also are utilized for in vitro symbiotic
germination of orchid seeds, aiming the conservation of plant species and
fungi. The objective of the present investigation was isolation and
morphological characterization of
mycorrhizal and endophytic fungi originating from roots of C. saintlegerianum
and E. nocturnum, as well as symbiotic in vitro seed germination. Three
isolates of Epulorhiza sp. from each one of C. saintlegerianum, and E.
nocturnum and two of Rhizoctonia sp. from E. nocturnum were obtained. Also,
two isolates of Xylaria sp. were obtained from roots of C.
saintlegerianum. There were, however, differences among isolates Epulorhiza
sp. of C. saintlegerianum and of the E. nocturnum, in relation to morphological
and enzymatic characters. The fungus was localized in root tissues of both
species by optical and scanning electronic microscopes. The seed viability was
tested by tetrazolium chloride and found 80.3 and 32.33% viable embryos of
C. saintlegerianum and E. nocturnum, respectively. There was no in vitro
symbiotic germination of E. nocturnum due to low seed viability. Two
experiments of symbiotic germination of C. saintlegerianum seeds were
conducted, both under photoperiods of 16/8 h (light/dark) at 26°C ± 2°C. The
treatments were two isolates
of Xylaria sp., three plant pathogens (Rhizoctonia solani of common beans and
R. oryzae of rice ), and three mycorrhiza of C. saintlegerianum, two of
Cyrtopodium vernum, and one ofE. nocturnum. Of three culture media tested,
germination was obtained only in oat meal agar culture. The isolate En07 of
Rhizoctonia sp. from E. nocturnum was found better for seed germination with
81.64 and 90.73% of germination of experiments 1 and 2, respectively.
One non-specific isolate, two plant pathogenic isolates and one specific isolate
were efficient for seed germination of C. saintlegerianum. On the other hand,
for symbiotic in vitro seed germination of C. saintlegerianum, there was no
specificity between this orchid and only one rhizoctonia-like fungus. These
results showed that C. saintlegerianum can be propagated utilizing different
root infecting fungi, which facilitates future programs of reintroduction
and commercialization of species.
Descrição
Citação
SOUSA, K. C. I. Caracterização morfológica de fungos para a germinação in vitro de sementes de Cyrtopodium saintlegerianum Rchb. f. e Epidendrum nocturnum Jacq.(Orchidaceae), ocorrentes no bioma cerrado. 2012. 127 f. Dissertação (Mestrado em Genética e Melhoramento de Plantas) - Universidade Federal de Goiás, Goiânia, 2012.