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在河南山药(Dioscorea opposita)主产品种‘铁棍山药’生产中出现了一种新的叶部病害,田间发病株率为6.6%。该病害主要发生在植株下部叶片,病斑圆形褐色,具同心轮纹,后期病斑上产生大量黑色孢子堆。对该病害的病原菌进行了组织分离培养和柯赫氏法则验证。其分生孢子座碗状或浅盘状,分生孢子梗呈笤帚状分枝,分生孢子梗顶端着生棒状产孢细胞;分生孢子长椭圆形、棒形、长卵形或梨形,透明无色,不分隔,两端钝圆,大小为1.7~2.5μm×4.9~6.8μm。病原菌菌落白色绒毛状,产生大量墨绿色胶质状分生孢子团,呈环状排列。用ITS通用引物对病原菌的基因组DNA进行扩增并测序(序列在GenBank的登录号为KY369166),同源性比对结果显示其与露湿漆斑菌(Myrothecium roridum)的一致性达到99%,结合形态学鉴定结果,确定该病害的病原菌为露湿漆斑菌。病原菌的最适生长温度为30℃,分生孢子致死温度为52℃,pH 5~10之间该菌生长良好,光暗(12 h/12 h)交替最有利于病原菌产孢,菌丝生长的最适碳氮源为乳糖和丙氨酸,产孢的最适碳氮源为果糖和酵母。
A new foliar disease occurred in the production of ’Ya Wang Ya Yao’, the main product of Henan yam (Dioscorea opposita), with an incidence rate of 6.6% in the field. The disease occurs mainly in the lower leaves of plants, disease spots round brown, with concentric ring pattern, a large number of late black spots on the spores pile. The pathogens of the disease were isolated and cultured by tissue culture and Koch’s law validation. Its conidia seat bowl or tray-shaped, conidiophores broom-like branches, conidiophores stems top rod-shaped spore cells; conidia oblong, stick, long-ovate or pear Shape, transparent and colorless, not separated, blunt round ends, the size of 1.7 ~ 2.5μm × 4.9 ~ 6.8μm. Pathogen colonies white fluffy, resulting in a large number of dark green gum-like conidia, was arranged in a ring. Genomic DNA of the pathogen was amplified with ITS universal primers and sequenced (the sequence of which was GenBank accession number KY369166). The homology comparison showed that the identity with Myrothecium roridum was 99% According to the results of morphological identification, the pathogen of this disease was identified as Staphylococcus aureus. The optimum growth temperature of pathogen was 30 ℃, the lethal temperature of conidia was 52 ℃, and the growth of the strain was good at pH 5 ~ 10. The light and dark (12 h / 12 h) The optimum carbon and nitrogen sources are lactose and alanine, and the optimum carbon and nitrogen sources for sporulation are fructose and yeast.