RESUMO
Coffee (Coffea arabica L.) is currently grown in many tropical and subtropical areas countries and is a major traded commodity for the developing world. Coffee leaf blight, caused by Phomopsis heveicola, is one of the most important fungal diseases dangerous to coffee crops in China. This study aimed to develop a PCR-based diagnostic method for detecting P. heveicola in planta. Specific primers (CPHF/CPHR) were designed based on sequence data of region of internal transcribed spacer (ITS1 and ITS4) of P. heveicola. The efficiency and specificity of CPHF/CPHR were established by PCR analysis of DNA from P. heveicola strains isolated from China and fungal isolates of other genera. A single amplification product of 318 bp was detected from DNA P. heveicola isolates. No amplification product was observed with any of the other fungal isolates tested. The specific primers designed and employed in PCR detected P. heveicola up to 3 pg from DNA isolated. This is the first report on the development of a species-specific PCR assay for identification and detection of P. heveicola. Thus, the PCR-based assay developed was very specific, rapid and sensitive tool for the detection of pathogen P. heveicola.
Assuntos
Coffea/microbiologia , DNA Fúngico/genética , Phomopsis/genética , Phomopsis/isolamento & purificação , Doenças das Plantas/microbiologia , China , Café , Primers do DNA/genética , Técnicas de Amplificação de Ácido Nucleico , Phomopsis/metabolismo , Reação em Cadeia da Polimerase/métodosRESUMO
Effects of toosendanin (TS) on the action potentials and contractile force in guinea pig papillary muscles were examined using a standard microelectrode technique. TS concentration-dependently increased the action potential duration at 90% repolarization (APD90) of the fast action potentials. In the presence of a Ikl channel blocker BaCl2, the effects of TS on lengthening the APD90 were completely abolished, thereby suggesting that TS inhibited the inward rectifier K+ current Ikl. The APD and contractile force of aminophylline-induced slow action potentials were potentiated by TS in a concentration-dependent manner. In the presence of BaCl2, both effects of TS were completely abolished. The effect of TS on enhancing contractile force was abolished by the addition of CdCl2, with the prolongation of APD preserved. Thus, TS selectively inhibited the inward rectifier K+ current Ikl with a positive inotropic effect, resulting from a delay in Ca channel inactivation which was secondary to delay in ventricular repolarization.