32个紫花苜蓿品种的种带真菌种类及致病性研究

Species and pathogenicity of seed-borne fungi in 32 varieties of alfalfa

植物病原菌通过种子可进一步在时间上延续和空间上传播。为确定我国目前主要种植的苜蓿品种是否携带苜蓿黄萎病菌等毁灭性病害的病菌和其他重要病菌,为苜蓿的引种调运和病害防治提供数据支撑,本研究从我国苜蓿育种者和经营进口苜蓿种子的公司收集了32个苜蓿品种,采用PDA平皿法分离并鉴定了种带真菌,采用浸种法测定了其对中苜3号的种子萌发、幼苗生长的致病性影响。结果表明,供试种子中未检测出苜蓿黄萎病菌及其他生产上的检疫性病原菌,苜蓿种子上的真菌主要为环境普遍存在的链格孢属、青霉属、曲霉属等真菌,共有19属20种;不同品种的种子带菌率有显著差异,不消毒处理下带菌率为26.18%~67.54%;消毒处理后平均种带真菌率有效降低了25.10%;枝孢霉、黑附球菌、枝顶孢、细交链孢等显著降低发芽率,篮状菌、球毛壳菌、黄曲霉、茄匍柄霉等菌对幼苗的芽和根有显著的抑制作用,严重的可引起幼苗枯萎、腐烂。

Plant pathogens can spread over time and in space via seeds.The aims of this study were to determine whether the main alfalfa varieties currently grown in China harbor pathogens causing destructive diseases,for example,Verticillium alfalfae,and to provide data to support the safe introduction,transportation,and disease control of alfalfa.We collected seeds of 32 alfalfa varieties from Chinese alfalfa breeders and importers.The fungi were isolated by the potato dextrose agar plate method and then identified.The pathogenicity of the fungal strains isolated from Zhongmu No.3 against seeds and seedlings was determined.Fungi in 19 genera,including 20 species of V.alfalfae and other quarantine pathogens,were detected from the tested seeds.The main fungi on alfalfa seeds were Alternaria spp.,Penicillium spp.,and Aspergillus spp.,which are common in the environment.There were significant differences in the frequency of seed-borne fungi among different alfalfa varieties.The percentage of seeds harboring pathogenic fungi was 26.18%-67.54%without disinfection,and disinfection decreased the average percentage of fungi by 25.10%.In pathogenicity tests against seeds,the seed germination percentage was significantly decreased by Cladosporium sp.,Epicoccus nigrum,Acremonium sp.and Alternaria alternata.In pathogenicity tests against seedlings,Talaromyces sp.,Chaetomium globosum,Aspergillus flavus,Stenophyllium solani,and other fungi significantly inhibited the shoot and root growth of seedlings,causing them to wither and rot.