烟草附球菌叶斑病的病原及生物学特性

【目的】明确贵州省烟草附球菌叶斑病病原菌种类及生物学特性，为烟草附球菌叶斑病的防控提供理论依据。【方法】以采集自贵州省烟区的烟草附球菌叶斑病叶为材料，使用常规组织分离法和离体叶片接种法分别对其病原菌进行分离和Koch’ s法则验证，使用形态学特征结合核糖体内转录间隔区（ITS）、28S rRNA（LSU）、β-微管蛋白（tub2）和RNA聚合酶II第二大亚基（rpb2）部分序列的多核苷酸序列系统学分析方法对病原菌进行鉴定，并使用菌落生长法研究病原菌生物学特性。【结果】从烟草附球菌叶斑病叶片病斑上分离获得病原菌（标记为YC1105），经ITS、LSU、tub2和rpb2 4个核苷酸片段序列和系统发育分析，菌株YC1105与Epicoccum latusicollum聚为一支，且支持率为100%；在PDA培养基上菌丝为红色，分生孢子椭圆形，单胞，大小为4.35~6.44 μm×2.10~3.27 μm，分生孢子器椭圆形，无刚毛，NaOH颜色反应呈阳性，其特征与Epicoccum latusicollum相符，结合形态特征和分子生物学方法将病原菌鉴定为E.latusicollum。病原菌生物学特性测定结果表明，菌株YC1105菌丝生长最适培养基为胡萝卜琼脂培养基，在5和10℃生长缓慢，最适温度为28℃，最适碳源为麦芽糖，最适氮源为牛肉浸粉，尿素不利于菌丝生长；病原菌在pH4~10范围内均能生长，最适pH为6，光照对菌丝生长影响不显著（P>0.05）；菌丝致死温度为49℃，水浴10 min。【结论】明确引起贵州烟草附球菌叶斑病的病原菌为Epicoccum latusicollum，该病原菌适宜在弱酸性条件下生长，菌丝生长温度范围较宽。

Pathogen and biological characteristics of tobacco Epicoccus leaf spot

【Objective】To investigate species and biological characteristics of Epicoccus leaf spot pathogen from tobacco in Guizhou Province，so as to provide scientific basis for tobacco Epicoccus leaf spot prevention and cintrol.【Method】 Tobacco leaves with Epicoccus leaf spot in Guizhou tobacco planting areas were taken as experiment material.And pathogen were isolated through tissue isolation method，and verified according to Koch’ s rule with detached-leaf inoculation method，respectively.The pathogen was identified according to morphological characteristics and polynucleotide sequence systematic analysis of ribosomal transcribed spacer（ITS），28S rRNA（LSU），β-tubulin（tub2）and the second largest subunit of RNA polymerase II（rpb2），and the biological characteristics of the pathogen were studied through colony growth method.【Result】The pathogen（labeled as YC1105）was isolated from infected tobacco leaves.According to the sequence and phylogenetic analysis of the 4 nucleotide fragments of ITS，LSU，tub2 and rpb2，the strain YC1105 and Epicoccum latusicollum were clustered into a branch，and the support rate was 100%.On PDA medium，the hyphae were red，the oval conidia whose size was 4.35-6.44 μm×2.10-3.27 μm，were ellipsoidal，aseptate，without bristles，and it showed positive reactions in the NaOH test，which was consistent with E.latusicollum.The pathogen was identified as E.latusicollum according to its morphological characteristics by molecular biological methods.Biological characteristics determination of pathogens showed that: the optimum medium for mycelial growth of YC1105 was carrot Agar；it grew slowly at 5 and 10℃ and the optimum temperature was 28℃；the optimum carbon source was maltose；the optimum carbon source was maltose；the optimum nitrogen source was beef dipping powder and urea was not conducive to the growth of mycelium；the pathogenic bacteria could grow in pH 4-10 and the optimum pH was 6；and the effect of light on the mycelium growth was not significant（P>0.05）；the lethal temperature of mycelium was 49℃，and the water bath was 10 min.【Conclusion】The pathogen causing tobacco Epicoccus leaf spot in Guizhou is identified as E.latusicollum，which grows well under weak acidic conditions，can grow under wide range of temperature.