我国城乡泡桐丛枝病区域差异因子分析

Affection factors of the regional difference of paulownia witches’-broom disease in urban and rural districts of China

为了解析与揭示我国泡桐丛枝病发生区域扩散和流行规律,科学制定病害防治策略与对策,分别于2018年至2020年在我国4大泡桐分布区内选取37个代表性城市与乡镇调查点,对泡桐丛枝病发病率和病情指数、泡桐种类与栽植生境等进行了调查;采集休眠病枝于室内水培萌芽和外植体组织培养,并提取泡桐总DNA采用PCR与LAMP方法检测植原体。研究结果表明,我国4大泡桐分布区中黄淮海暖温区和西北干旱区是该病害发生的重病区,而西南亚湿热区次之,江南温暖湿润区受害最轻。多数情况下,同一地区的城区与乡镇的总体发病率和危害程度存在一致性;在一些泡桐人工林主栽区与传统重病区呈现出中幼林发病率和病情指数明显降低的趋势。相关分析和回归分析结果表明,泡桐丛枝病病情指数与年均温度和年均降水量呈负相关关系。除来自陕西省西安市楸叶泡桐组培苗发病率和病情指数相对较低外,其他不同泡桐种类和地区来源染病外植体的组培苗发病率和病情指数分别达93.3%~100%和52.1~76.9,泡桐休眠病枝萌芽的植原体综合检出率为76.5%。因此认为我国泡桐丛枝病发生与危害的南轻北重差异受气候、寄主抗性以及种苗带菌等因子的影响;研究结果将为针对不同生境的泡桐丛枝病制定综合防控策略与科学决策提供理论依据。

This study aims to reveal the distribution and prevalence of paulownia witches’-broom(PaWB) disease in China,and to provide scientific strategies for paulownia witches’-broom control.The incidence and disease index of paulownia witches’-broom disease,paulownia species and climate factors were investigated in 37 representative cities and towns in China from 2018 to 2020.The dormant branches of paulownia were collected and cultured in water and grew in the greenhouse.PaWB phytoplasma was detected by PCR and LAMP.Huang-huai-hai Plain and Northwest China were still the most serious disease areas,followed by Southwest China and South of the Yangtze River.In most cases,the overall incidence and harm degree were consistent between urban and rural areas in the same region.In some main areas of paulownia plantation and historical severe disease areas,the incidence and disease index of young and middle-aged forests decreased significantly.Linear regression analysis showed that the disease index had a negative correlation with mean annual temperature and average annual precipitation.In addition to the relatively low incidence and disease index of tissue culture seedlings of Paulownia catalpifolia from Xi’an city,Shaanxi province,the incidence and disease index of tissue culture seedlings of other infected paulownia explants from different species and regions reached up to 93.3%-100% and 52.1-76.9,respectively.The positive rate of phytoplasma detection in sprouts of dormant branches of paulownia was 76.5%.PaWB phytoplasma can survive over winter in diseased branches.The difference of occurrence and severity of PaWB disease between southern and northern regions in China was affected by climate,host resistance and seedling carrying phytoplasma.The research provides a theoretical reference for prevention and control strategies and scientific decision making of PaWB disease in different habitats.