Identification and characterization of Phytopythium helicoids causing stem rot of ’Shatangju’ mandarin seedlings in China
作者单位：College of Horticulture and Plant ProtectionYangzhou University Plant Protection Research InstituteGuangdong Academy of Agricultural Sciences
会议名称：《中国植物病理学会第十二届青年学术研讨会》
会议日期：2015年
学科分类：09[农学] 0904[农学-植物保护] 090401[农学-植物病理学] 090402[农学-农业昆虫与害虫防治]
关 键 词：’Shatangju’ mandarin stem rot Phytopythium helicoids molecular barcode pathogenicity
摘 要：Citrus mandarin（Citrus reticulata） cultivar ’Shatangju’ possesses great economic importance in southern China because of its delicious fruits and medicinal *** surveys conducted in 2012 and 2013,a stem rot disease were observed on grafted ’Shatangju’ seedlings in 21 nurseries located in three regions（Yangjiang City,Sihui City and Deqing County） of Guangdong Province,*** aim of this study was to characterize the symptoms of seedling stem rot;evaluate the incidence and loss;identify the causal agent and evaluate its pathogenicity and *** disease was present in all surveyed nurseries but incidence varied with location.A Pythium-like oomycete species was consistently obtained from symptomatic plants collected in the nurseries *** the basis of morphological and cultural characteristics and combined phylogenetic analysis of four molecular barcodes including the internal transcribed spacer region（ITS）,β-tubulin,mitochondrial CoxⅠ and CoxⅡgenes,20 isolates obtained were identified as belonging to the species Phytopythium *** representative isolates were pathogenic to the scions but rootstocks of’Shatangju’ mandarin seedlings cultivated under nursery conditions and in a greenhouse and symptoms identical to that observed in the field were *** pathogen was reisolated consistently from the inoculated plants,confirming Koch’s *** stem rot and death caused by *** represents a serious threat to ’Shatangju’ mandarin nurseries productivity and longevity in southern China.