DataSheet_1_Dose-response relationship of Ralstonia solanacearum and potato in greenhouse and in vitro experiments.docx

Ralstonia solanacearum is the causative agent of bacterial wilt of potato and other vegetable crops. Contaminated irrigation water contributes to the dissemination of this pathogen but the exact concentration or biological threshold to cause an infection is unknown. In two greenhouse experiments, potted potato plants (Solanum tuberosum) were exposed to a single irrigation with 50 mL water (non-invasive soil-soak inoculation) containing no or 102 – 108 CFU/mL R. solanacearum. The disease response of two cultivars, Kondor and HB, were compared. Disease development was monitored over a three-month period after which stems, roots and tubers of asymptomatic plants were analyzed for latent infections. First wilting symptoms were observed 15 days post inoculation in a plant inoculated with 5x109 CFU and a mean disease index was used to monitor disease development over time. An inoculum of 5x105 CFU per pot (1.3x102 CFU/g soil) was the minimum dose required to cause wilting symptoms, while one latent infection was detected at the lowest dose of 5x102 CFU per pot (0.13 CFU/g). In a second set of experiments, stem-inoculated potato plants grown in vitro were used to investigate the dose-response relationship under optimal conditions for pathogen growth and disease development. Plants were inoculated with doses between 0.5 and 5x105 CFU/plant which resulted in visible symptoms at all doses. The results led to a dose-response model describing the relationship between R. solanacearum exposure and probability of infection or illness of potato plants. Cultivar Kondor was more susceptible to brown-rot infections than HB in greenhouse experiments while there was no significant difference between the dose-response models of both cultivars in in vitro experiments. The ED50 for infection of cv Kondor was 1.1x107 CFU. Results can be used in management strategies aimed to reduce or eliminate the risk of bacterial wilt infection when using treated water in irrigation.

Ralstonia solanacearum 为马铃薯及其他蔬菜作物细菌萎蔫病的病原体。灌溉水的污染是导致该病原体传播的重要因素，然而，引起感染的精确浓度或生物阈值尚不明确。在两项温室实验中，盆栽马铃薯（Solanum tuberosum）经单一灌溉处理（非侵入性土壤浸泡接种），灌溉水体积为50毫升，其中含有或不含R. solanacearum，浓度介于102至108 CFU/mL之间。对比了两种品种，Kondor和HB的病害反应。在接种后三个月内，监测了病害的发展，并对无症状植株的茎、根和块茎进行了潜伏感染的检测。在接种5x109 CFU的植株中，首次观察到萎蔫症状出现在接种后第15天，同时使用平均病害指数来监测疾病随时间的发展。每盆所需的最小剂量为5x105 CFU（土壤中为1.3x102 CFU/g），以引起萎蔫症状，而最低剂量为每盆5x102 CFU（土壤中为0.13 CFU/g），在该剂量下检测到一次潜伏感染。在另一组实验中，使用体外培养的茎部接种的马铃薯植株，以研究在病原体生长和病害发展最佳条件下，剂量反应关系。植株接种的剂量介于0.5至5x105 CFU/株之间，所有剂量下均出现可见症状。这些结果形成了一个剂量反应模型，描述了R. solanacearum暴露与马铃薯植株感染或疾病概率之间的关系。在温室实验中，Kondor品种对褐腐病的易感性高于HB，而在体外实验中，两种品种的剂量反应模型之间没有显著差异。cv Kondor的感染ED50为1.1x107 CFU。这些结果可用于制定旨在降低或消除使用处理水灌溉时细菌萎蔫病感染风险的管理策略。