铁皮石斛轮纹病病原菌鉴定及其防治药剂筛选

Identification of ring rot of Dendrobium officinale and screening of fungicides

为明确近年来在铁皮石斛Dendrobium officinale叶片及茎秆上出现的一种新病害—轮纹病的病原菌及筛选其有效防治药剂,通过分离物致病性测定、形态学观察和rDNA-ITS序列分析对病原菌进行鉴定,同时测定了11种药剂对病原菌菌丝生长和分生孢子萌发的抑菌效果。结果表明,从铁皮石斛病样中分离到的菌株TPLW01在致病性试验中表现出的症状与其田间自然感病症状一致,证明菌株TPLW01为铁皮石斛轮纹病的致病菌。该病原菌菌落在PDA培养基上初期为白色、绒毛状,后期菌落上长出同心环状排列的暗绿色至黑色的分生孢子座;分生孢子梗无色,圆柱形,有3~5轮分枝;分生孢子无色、单胞、杆状两端钝圆,大小为5.0~7.5μm×1.5~2.5μm;形态特征与露湿漆斑菌Myrothecium roridum一致。该菌rDNA-ITS序列的Gen Bank登录号为MF939638,与露湿漆斑菌(登录号KX421205.1)同源性为100.0%,分子鉴定结果与形态鉴定结果一致,确定引起该病的病原菌为露湿漆斑菌。6%春雷霉素可湿性粉剂1 000倍液、42.8%氟菌肟菌酯悬浮剂3 500倍液、29%吡萘嘧菌酯悬浮剂1 500倍液、70%甲基硫菌灵可湿性粉剂1 000倍液对该菌菌丝生长和分生孢子萌发的抑制效果均达到100.0%,表明这4种药剂可用于铁皮石斛轮纹病的田间防治。

In order to clarify the causal agent of ring rot, which was a new disease appeared on leaves and stems of Dendrobium officinale in recent years, the pathogenic fungus was identified, based on the analysis of pathogenicity tests of isolates, morphological characteristics and rDNA-ITS sequence. The inhibitory effects of 11 fungicides to the growth of mycelium and conidium germination of the pathogenic fungus were evaluated. The results showed that the strain TPLW01 was isolated from ring rot disease leaves of D. officinale, the symptoms of pathogenicity test were consistent with natural symptoms in the field, which proved that the strain TPLW01 was a pathogenic fungi. The colonies of the pathogen on PDA medium were initially white, floccose and then colonies grow dark green to black sporodochia with concentric rings in the later stage. Conidiophores were hyaline, cylindrical and in whorls of 3 to5. Conidia were hyaline, single celled, rod-shaped with rounded at both ends and measured between5.0-7.5 μm × 1.5-2.5 μm. These morphological characteristics consistent with M. roridum Tode ex Fr.The Gen Bank accession number of the rDNA-ITS sequence of TPLW01 was MF939638. Its homology with M. roridum（accession No. KX421205.1） was 100.0%. The results of molecular identification were consistent with the results of morphological identification, and the pathogen causing the disease was identified as M. roridum. The inhibitory effect of kasugamycin 6% WP 1 000 times, fluopyram · trifloxystrobin 42.8% SC 3 500 times, isopyrazam · azoxystrobin 29% SC 1 500 times and thiophanatemethyl 70% WP 1 000 times on mycelium growth and conidium germination of the pathogen M. roridum reached 100.0%, respectively. The four fungicides could be used to control ring rot of D. officinale in the field.