InvestigaÃÃo citogenÃtica do potencial alelopÃtico de espÃcies de lÃquens e pteridÃfitas / Cytogenetic investigation of the allelopathic potential of lichens and pteridophytas species.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

The allelopathic potential of two species of lichens (Myelochroa lindmanii and Canoparmelia texana) and two species of pteridophytas(Gleicheniella pectinata and Dicranopteris flexuosa) was evaluated by the effects of its aqueous extracts on germination, root growth and cytogenetic analysis in seeds of lettuce (Lactuca sativa) and maize (Zea mays). The extracts were obtained by leaf maceration in the distilled water (1/10). The treatments have been arranged in a completely randon design with 4 replications. Percent germination and root growth were evaluated at 12, 24, 36, 48, 60 and 72h after exposition. After 36h, eight roots were collected for cytogenetics analysis. The slides were prepared by the air drying technique. The four species showed allelopathic effect in all analysis accomplished. The aqueous extracts of the four species reduced percent germination and/or root growth. Furthermore, disturbance in the cell cycle and chromosome structure were observed after treatment. The cytogenetics alterations observed were,bridges, sticky chromosome, chromosome fragments, late segregation, chromosome duplication, cell death and c-metaphase. Frequencies of the different abnormalities were increased after treatments with aqueous extract of all species. Extract from Myelohroa lindmanii present as main effect the induction of cmetaphases, cell death and sticky chromosome. The c-metaphase alteration is particularity important for it represent an effect on the microtubule assembly. This hypotesis is supported by the observation of chromosome duplication and late segregation. After treatment with extract from Canoparmelia texana the same effect was not observed. The treatment with this specie cause increase of number the cell death and sticky chromosome as effect more evident. Extracts from Gleicheniella pectinata and Dicranopteris flexuosa caused more sticky chromosomes and cell death. Extracts obtained in diferentes seasons revealed that allelopathic potential this species were more evident in the periods with higher rain intensity.

ASSUNTO(S)

ciclo celular citogenotoxidade myelochroa lindmanii allelopaty citogenÃtica canoparmelia texana dicranopteris flexuosa cytogenotoxicity alelopatia myelochroa lindmanii gleicheniella pectinata cell cycle dicranopteris flexuosa citologia vegetal cytogenetics gleicheniella pectinata canoparmelia texana

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