单 位：
湘西民族职业技术学院;永顺县高坪乡农技和农村合作经济服务站
关键词：
西瓜炭疽病;18S rDNA-ITS;生物学特性;胶孢炭疽菌;菌落直径
摘 要：
探究湘西地区西瓜炭疽病致病种类,为西瓜炭疽病防控提供理论依据。以湘西民族职业技术学院科技园种植的西瓜病叶为研究对象,对该病的病原菌进行分离提纯、形态学观察、柯赫氏法则验证、18S rDNA-ITS序列分析以及生物学特性研究。菌株C913菌落呈圆形,菌丝绒毛状,排列整齐,初为白色,后渐为灰白色。轮状排列分生孢子盘,并有橘红色分生孢子团。分生孢子圆柱形,两端钝圆,单胞,中间有隔,大小(9.8～17.5)μm×(4.5～5.9)μm。18S rDNA序列与GenBank中收录的4个胶孢炭疽菌相似性达到100%。其菌丝在温度为10～37℃时均能生长正常,但25℃时菌丝生长速度最快,菌落直径为78.28 mm,小于10℃或大于37℃时较慢。菌丝孢子在pH 5～11条件下均能生长,其中,pH 6时菌丝生长最快,菌落直径最大,为84.62 mm。以葡萄糖、蔗糖作为碳源培养基的菌落直径极显著高于其他处理,分别为63.4、62.2 mm;而乳糖明显不利于其菌丝生长(P<0.01),为33.1 mm,比对照少19.06%。(NH_4)_2SO_4则明显对C913菌丝生长有抑制作用。根据菌株的形态学特征、18S rDNA-ITS序列分析结果,鉴定该菌株C913为半知菌亚门腔孢纲黑盘孢目炭疽菌属的胶孢炭疽菌Colletotrichum gloeosporioides,这是国内外首次在西瓜病叶上发现该病原菌。且温度20～31℃、pH 6时最适菌丝生长,而在温度为25～31℃、pH 9时最适产孢。以葡萄糖、蔗糖为碳源的培养基菌落直径最大,其菌落直径依次为蛋白胨>NaNO_3>甘氨酸>谷氨酸>琼脂>(NH_4)_2SO_4。
译 名：
Molecular Identification of a New Pathogen of Watermelon Anthracnose and Preliminary Study on Its Biological Characteristics
作 者：
HUANG Wei;CUI Lihong;XIE Wangchao;XIAO Guoqiang;Xiangxi Vocational and Technical College for Nationalities;Agricultural Technology and Rural Cooperative Economic Service Station,Gaoping Township, Yongshun County;
关键词：
watermelon anthracnose;;18S rDNA-ITS;;biological characteristics;;Colletotrichum gloeosporioides;;colony diameter
摘 要：
To explore the pathogenic species of watermelon anthracnose in western Hunan, and provide a theoretical basis for watermelon anthracnose prevention and control, we took the diseased leaves of watermelon grown in the Science and Technology Park of Xiangxi Vocational and Technical College for Nationalities as the research objects, isolated and purified the pathogen of the disease, and conducted morphological observation, Koch's rule verification, 18 S rDNA-ITS sequence analysis and the biological characteristics analysis. The colony of strain C913 was round, hyphae of villiform and neatly arranged. It was white at first and then grayish white. The conidia discs were arranged in a ring shape, and there were orangered conidia clusters. The conidia are cylindrical, blunt at both ends, single cell, with a septum in the middle,and the size was(9.8～17.5) μm ×(4.5～5.9) μm. The 18 S rDNA sequence was 100% similar to the four Colletotrichum gloeosporioides included in GenBank. The hyphae could grow normally when the temperature was 10-37℃, but the growth rate of the hyphae was the fastest at 25℃, and the colony diameter was 78.28 mm.The growth slowed down when the temperature was less than 10℃ or greater than 37℃. The hyphae spores could grow under the condition of pH 5-11. The hyphae grew fastest when the pH was 6 and the colony diameter was the largest, 84.62 mm. The colony diameter with glucose and sucrose as the carbon source medium was significantly higher than that of other treatments, 63.4 mm and 62.2 mm, respectively; while lactose was not conducive to the growth of mycelium(P<0.01), which was 33.1 mm, and 19.06% less than that of the control.(NH_4)_2 SO_4 obviously inhibited the growth of C913 hyphae. According to the morphological characteristics of the strain and the results of 18 S r DNA-ITS sequence analysis, the strain C913 was identified as Colletotrichum gloeosporioides of the genus Colletotrichum of the subphylum Coelospora. The pathogen is found on diseased leaves of watermelon for the first time. When the temperature is 20-31℃ and pH is 6, it is the most suitable condition for mycelial growth, and when the temperature is 25-31℃ and pH is 9, it is the most suitable condition for sporulation. The colony diameter is the largest in the medium with glucose and sucrose as carbon sources, and the colony diameter is in the order of peptone>NaNO_3>glycine>glutamic acid>agar>(NH_4)_2SO_4.
