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近年,柑橘黑斑病成为阻碍我国柑橘鲜果出口贸易的瓶颈,广东梅州名优鲜果蜜柚生产基地也遇到类似情况。该病发生后,病果果皮表面产生许多圆形病斑,初呈红褐色,中间凹陷,直径多为2~3mm,后期病斑逐渐转为褐色至黑褐色,病斑中部明显可见细小的黑色粒点状分生孢子器。病果分离物的培养性状与形态特征与柑橘黑斑病菌(柑橘球座菌,Guignarida citricarpa)一致。采用真菌ITS通用引物和柑橘球座菌特异性引物,从病斑组织基因组DNA及分离物基因组DNA中分别扩增得到541bp和396bp的片段。BLAST分析表明:扩增到的片段均与GenBank中已知柑橘球座菌菌株的rDNAITS序列相似性最高,分别为97%和98%。根据分离菌株的培养性状和形态特征及ITS区序列分析结果,将梅州蜜柚上的柑橘黑斑病菌鉴定为柑橘球座菌(Guignarida citricarpa Kiely)。
In recent years, citrus black spot has become a bottleneck impeding the export trade of citrus fruits in China. Meiyu, a famous fresh fruit pomelo production base in Guangdong, also encountered a similar situation. After the occurrence of the disease, there are many circular lesions on the surface of diseased fruit peel, initially showed a reddish-brown, the middle of the depression, the diameter of mostly 2 ~ 3mm, late lesions gradually turned brown to dark brown, lesion obvious visible small black Pollen conidia. The cultivated traits and morphological characteristics of diseased fruit isolates were consistent with those of Alternaria citri (Guignarida citricarpa). Fragments of 541bp and 396bp were amplified from the genomic DNA of the diseased tissue and the genomic DNA of the isolates respectively using fungi ITS universal primers and Citrus tupaiae specific primers. BLAST analysis showed that the amplified fragments all had the highest similarity to the rDNAITS sequences of known Citronella citrus strains in GenBank, which were 97% and 98% respectively. According to the culture characteristics and morphological characteristics of the isolated strains and ITS sequence analysis, the black spot pathogen of Citrus pumila on Meizhou honey pomelo was identified as Guignarida citricarpa Kiely.