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报道了中国广西田林县油桐主产区一种新的叶片真菌病害,定名为油桐叶枯病。该病主要为害叶片,病菌侵染后叶片呈现灰褐色病斑,后期扩至整个叶片,引起过早脱落,影响油桐产量。从采集的带病标本中分离到16个纯培养物,隶属5个分类单元。依据柯赫法则和致病性测定,证明只有菌株VT-04为油桐叶枯病的病原物。在病斑组织中观察不到有性或无性繁殖结构,而该病原菌在诱导培养(含无菌松针的水琼脂+近紫外照射)条件下可产生子实体。比较培养性状、产孢结构特征并结合分析核糖体rDNA基因转录间隔区(ITS)和RNA聚合酶次大亚基基因(RPB2)序列和系统发育关系,将该病原菌鉴定为葡萄座腔菌科Botryosphaeriaceae中的一种无性型菌物,即小新壳梭孢Neofusicoccum parvum。这是首次在油桐叶片上发现由该病菌引起的病害。
A new leaf fungal disease was reported in the main producing area of Tung Oil Field in Tianlin County, Guangxi Province, China, and was named as the oil tar leaf blight. The disease is mainly affected leaves, the pathogen infected leaves gray brown spots, the late expansion to the entire leaves, causing premature shedding, affecting the production of tung tree. Sixteen pure cultures were isolated from the diseased specimens collected, belonging to five taxonomic units. According to Kohn’s law and pathogenicity test, only strain VT-04 was proved to be the pathogen of oil tar leaf blight. No vegetative or asexual reproductive structures were observed in the lesion tissues, whereas the pathogen could produce fruiting bodies under induction culture (water agar with sterile pine needles + near UV irradiation). The characteristics of sporulation and sporulation were compared and analyzed. The results showed that the pathogen was identified as Botryosphaeriaceae by combining the analysis of rDNA gene spacer region (ITS) and RNA polymerase subunit gene (RPB2) In a non-mycotoxin, Neococcinia minor Neofusicoccum parvum. This is the first time that P. euphorbiae leaves have been found to cause disease caused by this pathogen.