湖南多花黄精根腐病病原菌的分离与鉴定

【目的】明确多花黄精根腐病在湖南地区的发生规律及其病原菌种类，为湖南多花黄精根腐病的综合防治及GAP （中药材生产质量管理规范）种植提供科学依据。【方法】以湖南地区具有典型根腐病症状的多花黄精植株为材料，采用传统的平板分离法对其病原菌进行分离纯化，通过rDNA-ITS序列分析及形态学观测鉴定病原菌的种类和分类地位，并依据Koch's法则验证病原菌的致病性。【结果】湖南地区的多花黄精根腐病以生长旺盛期（5—7月）发生最严重，平均发病率为12%，严重时可达20%；发病部位主要是多花黄精根部。从患典型根腐病多花黄精根茎的病健交界处分离获得4株分离菌株（G1~G4），菌株G1、G2和G4经PCR扩增分别获得511、573和573 bp的目的条带，菌株G3因PCR扩增条带混杂，导致测序失败。菌株G1与F.foetens（GenBank登录号NR_159865.1）的rDNA-ITS序列相似性为99.22%，菌株G2和G4与F.hostae（GenBank登录号NR_171109.1）的rDNA-ITS序列相似性为99.81%。菌株G1在PDA培养基上生长较快，培养7 d后其菌落直径为6.7 cm，气生菌丝致密，呈毡状，白色至粉紫色；菌株G2和G4在PDA培养基上培养7 d后其菌落直径为6.2 cm，气生菌丝呈放射状，白色至淡黄色。将菌株G1、G2和G4分别接种至健康多花黄精植株的根茎上，接种10 d后均表现出强致病性，呈典型的根腐病发病症状。其中，菌株G1接种10 d后多花黄精根茎开始变褐腐烂，且伴有明显的腥味；菌株G2和G4接种10 d后多花黄精根茎初期变褐色，后期病斑腐烂部分的根茎出现凹陷。【结论】不同地理位置、栽培方式及黄精品种，均有可能导致黄精根腐病的发生情况及其病原菌存在差异，在一定程度上增加了黄精根腐病防治工作的难度，且给后期的产品加工带来安全隐患。F.foetens和F.hostae是引起湖南多花黄精根腐病的致病菌。

Isolation and identification of the pathogenic fungi of Polygonatum cyrtonema Hua root rot in Hunan Province

【Objective】 Clarify the regularity of outbreak and pathogenic fungi of Polygonatum cyrtonema Hua root rot in Hunan, and provide a scientific basis for the comprehensive control of P. cyrtonema root rot and GAP(Good Agricultural Practice for Chinese Crude Drugs) planting.【Method】 Samples with typical symptoms of root rot were collected in Hunan, the pathogen of P. cyrtonema Hua root rot was isolated and purified by plate isolation and purification. The classification status of the pathogen was determined based on their morphological characteristics and r DNA-ITS sequence, and Koch's rule was used to prove the pathogenicity of fungal strain isolated from P. cyrtonema Hua.【Result】 The P. cyrtonema Hua root rot in Hunan was the most serious at growth stage(May-July), with the average incidence of 12% and 20% when serious;the incidence site was mainly root. Four strains(G1-G4) were isolated from the healthy junction of P.cyrtonema Hua rhizome suffering from typical root rot. The isolated and purified strains G1, G2 and G4 were amplified by PCR to obtain DNA fragments with a length of 511, 573 and 573 bp bands, respectively. Due to PCR amplification bands mixed, strain G3 sequencing was failed. According to BLAST homology comparison of pathogen r DNA-ITS sequence, the sequence of strain G1 shared the high identity of 99.22% with Fusarium foetens(GenBank accession number NR_159865.1), while the sequence of strains G2 and G4 had 99.81% similarity with F. hostae(GenBank accession number NR_171109.1). Strain G1 grew rapidly on PDA medium, and after 7 d of culture, colony diameter was 6.7 cm, aerial mycelium was dense, felt shape, white to pink purple;and after 7 d of culture, colony diameters of strains G2 and G4 were 6.2 cm, aerial mycelium was radial, white to pale yellow. Isolates G1, G2 and G4 were infected onto the rhizomes of healthy P. cyrtonema Hua plants, and both were strongly pathogenic and showed typical symptoms of root rot onset. P.cyrtonema Hua root infected by G1 began to decompose and brownish 10 d after infection with obvious fishy smell;10 d after strains G2 and G4 infection, P. cyrtonema Hua root turned brown, then the tubers in the rotten part of the diseased spot appear depressed.【Conclusion】 Different geographical locations, cultivation methods and P. cyrtonema Hua varieties can lead to differences in the occurrence of P. cyrtonema Hua root rot and its pathogens, which increases the difficulty of the prevention and control of P. cyrtonema Hua root rot to a certain extent, and brings safety risks to the processing of later products. F. foetens and F. hostae are the pathogens that cause P. cyrtonema Hua root rot in Hunan.