山茶花腐病病原菌的分离鉴定及生物学特性

Pathogen Identification and Biological Characterization of Camellia Petal Blight Disease

【目的】明确山茶花腐病的致病菌及其生物学特性,提升山茶花期品质和观赏价值。【方法】采用组织分离法对云南省昆明市昆明植物园山茶的花腐病进行病原菌分离,通过致病性测定、形态学和分子生物学鉴定确定病原菌,并进行生物学特性的研究。【结果】从病组织中分离得到1株菌株,将其回接于健康花瓣上,接种后划破的花瓣病症较为明显,花朵失色变黄褐,严重时能使花瓣干腐或湿腐,并且长菌丝体,与田间的症状一致,符合柯赫氏法则的致病性测定。PDA培养基上菌丝偏黄,培养后期长黑色的孢子,子囊孢子柠檬状,经合并多基因(ITS、LSU、EF1)系统发育分析,其与假螺卷毛壳菌(Chaetomium pseudocochliodes)聚集在同一分支。对假螺卷毛壳菌(C.pseudocochliodes)的生物学特性研究结果显示,该病原菌的最适培养温度为25℃,对光照条件没有特殊要求,最适培养基为LB和OMA培养基,以牛肉膏作为氮源和以果糖作为碳源的利用率最高,致死温度为55℃/10 min。【结论】假螺卷毛壳菌(C.pseudocochliodes)是山茶花腐病的病原菌,该病原菌的适宜温度为25℃,不受光照影响,培养基为LB和OMA培养基,以牛肉膏作为氮源和以果糖作为碳源的利用率最高,致死温度为55℃/10 min。

【Objective】The pathogen and its biological characteristics of camellia petal blight disease were investigated for improving the quality and protecting the ornamental value of the floral plant.【Method】A pathogen was isolated from of diseased Camellia japonica at the Botanical Garden in Kunming City by tissue separation method and confirmed by pathogenicity assay as well as morphological and molecular biological identifications.Biological characteristics of the isolate were studied.【Result】A suspected microbe was isolated from the diseased tissue and inoculated onto healthy camellia flower petals.With the appearance of yellowing and browning petals with dry or wet rots and fungal mycelial growth,the similar symptoms shown on the infected plants in the field,the isolate was studied further for a confirmed identification.On a PDA medium,the fungal colonies displayed yellow mycelia and produced black spores and lemon-like ascospores at late stage.The phylogenetic analysis of multiple genes of ITS,LSU,and EF1 clustered the isolate with Chaetomium pseudocochliodes clade.Subsequently,the optimal conditions for the growth of the isolated fungus were found to be at 25℃on LB and OMA culture medium,without special requirement of light,beef paste as a nitrogen source and fructose as a carbon source have the highest utilization rates,and the lethality at 55℃in 10 min.【Conclusion】C.pseudocochliodes was identified as the pathogen that caused floral petal blight disease on C.japonica.The pathogen grew optimally at 25℃on LB and OMA culture medium,without a specific light requirement,beef paste as a nitrogen source and fructose as a carbon source have the highest utilization rates,and it was killed by exposure to 55℃for 10 min.