尖孢镰刀菌苜蓿专化型厚垣孢子的诱导形成方法及萌发特性  

Induced formation method and germination characteristics of chlamydospores by Fusarium oxysporum f.sp.medicaginis

作　　者：方香玲 许世洋 南志标[1] FANG Xiang-ling;XU Shi-yang;NAN Zhi-biao(Center for Grassland Microbiome,State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems,College of Pastoral Agriculture Science and Technology,Lanzhou University,Lanzhou 730020,China)

机构地区：[1]兰州大学草地微生物研究中心,草种创新与草地农业生态系统全国重点实验室,兰州大学草地农业科技学院,甘肃兰州730020

出　　处：《草业学报》2024年第7期130-141,共12页Acta Prataculturae Sinica

基　　金：国家重点研发计划项目(2022YFD1300802);国家自然科学基金项目(32171678);中美国际合作项目(32161123002)资助。

摘　　要：厚垣孢子是尖孢镰刀菌在土壤中的主要存活结构,土壤中厚垣孢子的数量及萌发状况,直接影响着病害的发生及其严重度。首先通过研究合成低营养琼脂(SNA)和SNA加滤纸片(SNAF)培养基以及不同浓度葡萄糖和碳酸镁的双盐溶液(KH_(2)PO_(4)和MgSO_(4)·7H_(2)O)中厚垣孢子的形成,建立苜蓿专化型菌株厚垣孢子的诱导形成方法并进行验证,然后研究不同碳源和氮源对厚垣孢子萌发的影响。菌株T6和T9在2 mg·L^(-1)葡萄糖的双盐溶液中静置培养7 d时形成大量的厚垣孢子,分别为4.2×10^(5)和5.1×10^(5)个·mL^(-1);且静置培养时的厚垣孢子数量均高于振荡培养时的数量,分别为4.2和2.8倍。不同苜蓿专化型菌株经双盐溶液诱导后,都在培养7 d时形成大量厚垣孢子,且培养前7 d时数量都快速增加,7 d时的均值为3 d时的2.3倍;而培养14和21 d时数量增加较慢,21 d时的均值仅为7 d时的1.2倍。对厚垣孢子萌发及芽管生长促进作用较大的碳源和氮源分别为葡萄糖和氯化铵,促进作用较小的碳源和氮源分别为乳糖和尿素。结果表明尖孢镰刀菌苜蓿专化型菌株厚垣孢子的形成需要微量的碳源和低氧环境,且厚垣孢子的萌发及生长需要适宜的碳源和氮源,可从控制病原菌初侵染源角度为苜蓿土传病害的绿色防控提供新思路。Chlamydospores are the main survival structure of Fusarium oxysporum in soil,and the number and germination status of chlamydospores in soil directly affects the occurrence and severity of the disease.In this study,we established a system to induce chlamydospore production by F.oxysporum f.sp.medicaginis(Fom)by culturing the pathogen on synthetic low nutrient agar(SNA)medium,synthetic low nutrient agar with filter(SNAF)medium,or in two-salt solution(KH_(2)PO_(4) and MgSO_(4)·7H_(2)O)with glucose or magnesium carbonate at a range of concentrations.The chlamydospore induction system was verified,and the effects of different carbon and nitrogen sources on chlamydospore germination were studied.The T6 and T9 strains of Fom produced many chlamydospores after static culture for 7 days in the two-salt solution with glucose at 2 mg·L^(-1),producing 4.2×10^(5) and 5.1×10^(5) chlamydospores per mL,respectively.Both T6 and T9 produced more chlamydospores under static culture than under shaking culture(4.2-and 2.8-times,respectively,at 7 days of culture).All Fom strains produced many chlamydospores after 7 days of culture in the two-salt solution,with a rapid increase of 2.3-times compared with 3 days,followed by slow increases at 14 and 21 days,with an average increase of only 1.2-times from 7 to 21 days of culture.Comparing all the carbon and nitrogen sources,glucose and ammonium chloride had the strongest promoting effects on the germination and germ tube growth of chlamydospores,whereas lactose and urea had the weakest effects.The results show that chlamydospore formation by Fom strains requires a trace amount of a carbon source and a low-oxygen environment,and the germination and growth of chlamydospores require suitable carbon and nitrogen sources.These findings provide new insights into effective management of soil-borne diseases in alfalfa through controlling the primary infection source,i.e.,the chlamydospores of the pathogen.

关 键 词：尖孢镰刀菌 土传病原真菌 存活结构 初侵染源 厚垣孢子 

分 类 号：S435.4[农业科学—农业昆虫与害虫防治]