The fungal disease smut (causal agent: Ustilago scitaminea H. & P. Sydow) and stalk borer eldana (Eldana saccharina Walker) place major constraints on sugarcane agriculture in South Africa. Although various methods are being applied to manage smut and eldana, the best approach is the introduction of resistant cultivars. However, conventional field-based screening for pest and disease resistance requires several years. This study evaluates in vitro techniques combined with artificial inoculation as rapid screening methods. Inoculation of sugarcane at two developmental stages was investigated: 3 month old plantlets derived from apical meristems and 8–10 week old embryogenic callus derived from immature leaf rolls. U. scitaminea spores were collected from field-infected sugarcane, surface decontaminated by a 3× wash in 0.5 g/l streptomycin sulphate solution and cultured to generate infective sporidia. Two concentrations of sporidial suspensions (1 × 106 and 1 × 109 sporidia ml−1) were used to inoculate plantlets (0.5 µl with a Hamilton® syringe, applied 1 cm above the apical meristem) and callus (via dipping, soaking and vacuum infiltration). The development of a characteristic smut whip was observed in vitro after 10–12 weeks. Evaluation using callus is underway. Surface decontamination of 5 day old eldana eggs was achieved by exposure to 1% sodium hypochlorite (NaOCl) for 15 min. Feeding bioassays were conducted by placement of first instar larvae on in vitro plantlets and callus. Larval mass and length were recorded after 3 and 2 weeks respectively. Preliminary investigations were conducted on cultivar NCo376 which is susceptible to smut and eldana. Future investigations will be conducted on five ‘test’ cultivars whose identity and associated field resistance rating will remain undisclosed until completion of the experiments. Data subjected to statistical analyses will be used to assess the accuracy of an in vitro approach. Finally, the most suitable screening methods for evaluating sugarcane susceptibility to smut and eldana will be determined.
The fungal disease smut (causal agent: Ustilago scitaminea H. & P. Sydow) and stalk borer eldana (Eldana saccharina Walker) place major constraints on sugarcane agriculture in South Africa. Although various methods are being applied to manage smut and eldana, the best approach is the introduction of resistant cultivars. However, conventional field-based screening for pest and disease resistance requires several years. This study evaluates in vitro techniques combined with artificial inoculation as rapid screening methods. Inoculation of sugarcane at two developmental stages was investigated: 3 month old plantlets derived from apical meristems and 8–10 week old embryogenic callus derived from immature leaf rolls. U. scitaminea spores were collected from field-infected sugarcane, surface decontaminated by a 3× wash in 0.5 g/l streptomycin sulphate solution and cultured to generate infective sporidia. Two concentrations of sporidial suspensions (1 × 106 and 1 × 109 sporidia ml−1) were used to inoculate plantlets (0.5 µl with a Hamilton® syringe, applied 1 cm above the apical meristem) and callus (via dipping, soaking and vacuum infiltration). The development of a characteristic smut whip was observed in vitro after 10–12 weeks. Evaluation using callus is underway. Surface decontamination of 5 day old eldana eggs was achieved by exposure to 1% sodium hypochlorite (NaOCl) for 15 min. Feeding bioassays were conducted by placement of first instar larvae on in vitro plantlets and callus. Larval mass and length were recorded after 3 and 2 weeks respectively. Preliminary investigations were conducted on cultivar NCo376 which is susceptible to smut and eldana. Future investigations will be conducted on five ‘test’ cultivars whose identity and associated field resistance rating will remain undisclosed until completion of the experiments. Data subjected to statistical analyses will be used to assess the accuracy of an in vitro approach. Finally, the most suitable screening methods for evaluating sugarcane susceptibility to smut and eldana will be determined.
การแปล กรุณารอสักครู่..