重庆市丘陵地区马铃薯晚疫病流行规律、病原菌群体遗传及其抗药性分析

Epidemics of potato late blight, pathogen population genetics, and drug resistance analysis in hilly areas of Chongqing

中文关键词:马铃薯晚疫病  流行规律  群体结构  抗药性  遗传变异  致病疫霉

keywords:potato late blight  epidemics  population structure  fungicide resistance  genetic variation  Phytophthora infestans

中文摘要:为实现重庆市丘陵地区马铃薯晚疫病的精准防控，基于2022—2024年丰都县3个马铃薯晚疫病测报点预警系统数据分析该地区晚疫病初始适宜发病时间及流行程度，总结晚疫病流行规律，利用12对简单重复序列（simple sequence repeat，SSR）标记对分离的晚疫病菌——致病疫霉Phytophthora infestans菌株进行群体遗传及变异分析，并通过平板对峙法测定氰霜唑及霜脲氰对供试病原菌的EC₅₀，分析田间菌株对药剂的敏感性。结果显示：2022—2024年重庆市丰都县在2月上旬至3月中旬出现适宜晚疫病菌侵染的温湿度，且出现时间随海拔升高而推迟；3年间3个测报点晚疫病菌的侵染代数介于6~18代之间，侵染次数介于43~99次之间；初始适宜发病时间越晚，侵染代数越低。2022—2024年共分离菌株116株，其中有85.57%的菌株与致病疫霉EU_13_A2基因型菌株类似，其余菌株与US-11基因型菌株类似，总体上年度间晚疫病菌群体结构变化较大。分离菌株对氰霜唑及霜脲氰的敏感性频率分布呈现连续单峰型，无抗性菌株。表明重庆市丘陵地区马铃薯晚疫病适宜发病期相对稳定，晚疫病菌群体结构变化快，未出现霜脲氰及氰霜唑抗性菌株，这2种药剂仍可用于当地马铃薯晚疫病的防控。

Abstract:To achieve precise control of late blight of potato in the hilly regions of Chongqing, this study investigates the initial favorable conditions for disease onset and its severity based on three late blight warning systems in Fengdu County from 2022—2024. Population genetics and variation were analyzed using 12 simple sequence repeat (SSR) markers. The sensitivity of these isolates to the cymoxanil and cyazofamid was assessed with EC₅₀ values. The result indicated that, from early February to mid-March, temperature and humidity levels in Fengdu County were conducive to Phytophthora infestans infection, with the onset of favorable conditions delayed with increasing elevation. Across three monitoring sites over three years, the number of infection cycles ranged from six to 18, with 43 to 99 infection events observed. A later onset of favorable conditions for infection was associated with fewer infection cycles. Of the 116 isolates collected between 2022 and 2024, 85.57% were genetically similar to the EU_13_A2 genotype, while the remaining isolates were similar to the US-11 genotype. The P. infestans population exhibited significant genetic variation over time. Sensitivity frequency distributions of the isolates to cymoxanil and cyazofamid showed a continuous unimodal distribution, with no resistant isolate detected. These findings suggest that the favorable period for potato late blight development in the hilly regions of Chongqing is relatively stable, while the P. infestans population undergoes rapid structural changes. No resistance to cymoxanil or cyazofamid was detected, indicating that these two fungicides remain effective for potato late blight management in this region.