Department of Plant Sciences, University of California, Davis, CA, USA.
Phytopathology. 2011 Dec;101(12):1492-500. doi: 10.1094/PHYTO-08-10-0207.
Pierce's disease (PD) of Vitis vinifera grapevines is caused by the bacterium Xylella fastidiosa, a pathogen with a wide plant host range. Exposure of X. fastidiosa-infected plant tissue to cold temperatures has been shown to be effective at eliminating the pathogen from some plant hosts such as grapevines. This "cold curing" phenomenon suggests itself as a potential method for disease management and perhaps control. We investigated cold therapy of PD-affected 'Pinot Noir' and 'Cabernet Sauvignon' grapevine. In the fall, inoculated plants and controls of each cultivar were transported to each of four field sites in California (Foresthill, McLaughlin, Hopland, and Davis) that differed in the magnitude of cold winter temperatures. A model for progression of the elimination of plant disease in relation to temperature was conceptualized to be a temperature-duration effect, where temperatures below a particular threshold kill X. fastidiosa with increasing efficacy as the temperature decreases to some value <6?C. The temperature effect was modeled as a likelihood of a particular temperature killing the pathogen and is termed the ?killing index?. We developed a mathematical model for cold curing of grapevines inoculated with X. fastidiosa and calibrated the model with cold-curing data collected in a field study. Parameter estimation resulted in lowest sum of squared differences across all 10 trials to be low temperature below which the organism is killed (T(0)) = 6°C, number of hours to achieve 100% cure (N(100)) = 195 h, number of hours to achieve 10% cure (N(10)) = 20 h, and killing index (K(x)) = 0.45 for Pinot Noir and T(0) = 6°C, N(100) = 302 h, N(10) = 170 h, and K(x) = 0.41 for Cabernet Sauvignon. With the parameter estimates optimized by model calibration, the simulation model was effective at predicting cold curing in four locations during the experiment, although there were some differences between Hopland for Pinot Noir and Davis for Cabernet Sauvignon. Using historical temperature data, the model accurately predicted the known severity of PD in other grape-growing regions of California, suggesting that it may have utility in assessing the relative risk of developing PD in proposed new vineyard sites.
葡萄皮尔逊病（PD）是由韧皮部杆菌（Xylella fastidiosa）引起的，该病菌的寄主范围广泛。研究表明，将受感染的植物组织暴露在低温下，可有效清除一些植物寄主（如葡萄藤）中的病原体。这种“冷处理”现象为疾病管理，甚至可能是控制疾病提供了一种潜在方法。我们研究了受 PD 影响的‘黑比诺’和‘赤霞珠’葡萄的冷疗方法。在秋季，每个品种的接种植物和对照植物被运往加利福尼亚的四个田间地点（福雷斯特希尔、麦克劳克林、霍普兰和戴维斯），这些地点的冬季低温差异很大。我们设想了一个与温度相关的消除植物病害进展的模型，认为这是一个温度-时间效应，当温度低于特定阈值时，随着温度降低到<6°C 的某个值，韧皮部杆菌的致死率会逐渐增加。该温度效应被建模为特定温度杀死病原体的可能性，并称为“致死指数”。我们为接种了韧皮部杆菌的葡萄藤建立了冷疗数学模型，并使用田间研究中收集的冷疗数据对模型进行了校准。通过对所有 10 次试验的最小平方和进行参数估计，得出了最低的差异，结果表明，生物体被杀灭的低温（T(0)）为 6°C，达到 100%治愈率（N(100)）所需的小时数为 195 小时，达到 10%治愈率（N(10)）所需的小时数为 20 小时，以及‘黑比诺’的致死指数（K(x)）为 0.45，而‘赤霞珠’的 T(0)为 6°C，N(100)为 302 小时，N(10)为 170 小时，K(x)为 0.41。利用模型校准优化的参数估计值，该模拟模型能够有效地预测实验期间四个地点的冷疗效果，尽管在黑比诺的霍普兰和赤霞珠的戴维斯之间存在一些差异。利用历史温度数据，该模型准确预测了加利福尼亚其他葡萄种植区已知的 PD 严重程度，表明它可能有助于评估拟议的新葡萄园地点发生 PD 的相对风险。
