DataSheet_2_Effect of temperature and humidity on dynamics and transmission of Pseudomonas amygdali pv. lachrymans aerosols.docx

Cucumber angular leaf spot (ALS) disease, caused by Pseudomonas amygdali pv. lachrymans (Pal), is an emerging disease with a high incidence that causes severe damage to cucumber worldwide. Bacterial aerosols play a crucial role in the epidemiology of greenhouse ALS disease. However, little is known about the influence of temperature and relative humidity (RH) on the dynamics of Pal in aerosols. A study was conducted to investigate the relationships between the concentration of Pal aerosols and their dependence on temperature and RH in aerosol chambers and greenhouses. The results demonstrated that temperature and RH are both significant factors influencing the release amount, survival time and infectivity of Pal in aerosols, while RH has a greater influence on particle size than temperature across the range of conditions tested. The release amount and survival time of Pal in aerosols under high RH (95%) and low temperature (≤ 25°C) conditions were significantly higher than those under low RH (35%) and high temperature (35°C) conditions. The highest release amount of Pal aerosol (96 CFU/m3) and highest survival rate (98.41%) were found at 18°C and 95% RH, while the highest disease index (DI = 60.9) caused by Pal aerosol was found at 25°C and 95% RH. In addition, Pal aerosols presented a larger diameter (4.7->7.0 μm) under high RH (95% RH) than under dry conditions (≤ 65% RH). These findings will play a crucial role in elucidating the influence of environmental parameters on the dynamics and transmission of Pal in aerosols. Based on our findings, preliminary recommendations for controlling airborne Pal spread involve controlling air temperature and RH, which will contribute to the effective alleviation and control of cucumber ALS disease.

黄瓜细菌性角斑病（Cucumber angular leaf spot, ALS）是由丁香假单胞杆菌黄瓜角斑病致病变种（Pseudomonas amygdali pv. lachrymans, Pal）引发的新兴病害，在全球范围内发病率较高，对黄瓜生产造成严重危害。气传细菌气溶胶在温室黄瓜角斑病的流行过程中发挥关键作用。然而，目前学界对温度与相对湿度（relative humidity, RH）如何影响气溶胶中Pal的种群动态仍尚不明确。本研究通过气溶胶箱与温室试验，探究了Pal气溶胶浓度与温度、相对湿度之间的关联规律。
研究结果显示：在试验涵盖的环境条件范围内，温度与相对湿度均为影响Pal气溶胶释放量、存活时长与侵染活性的显著因子；且相较于温度，相对湿度对气溶胶粒径的影响更为显著。在高相对湿度（95%）、低温（≤25℃）条件下，Pal气溶胶的释放量与存活时长均显著高于低相对湿度（35%）、高温（35℃）条件。其中，18℃、95% RH条件下Pal气溶胶的释放量最高（96 CFU/m³），存活率达98.41%；而25℃、95% RH条件下，Pal气溶胶引发的病情指数（disease index, DI）最高（DI=60.9）。此外，高湿环境（95% RH）下Pal气溶胶的粒径范围为4.7~7.0 μm，显著大于干燥环境（≤65% RH）下的粒径。
本研究结果可为阐明环境参数对气溶胶中Pal种群动态与传播的影响提供重要理论支撑。基于本研究发现，防控气传Pal扩散的初步建议为调控空气温度与相对湿度，该措施将有助于有效减轻并防控黄瓜细菌性角斑病的发生。