铁皮石斛圆斑病病原菌鉴定及其生防菌筛选

Identification of the Pathogen for Round Spot on Dendrobium officinale and Screening of the Biocontrol Fungus Against It

在云南普洱铁皮石斛种植基地进行病害调查时发现,铁皮石斛圆斑病发病率为30%左右.为探明引起铁皮石斛圆斑病的病原菌种类,并筛选出对该病原菌有明显抑制效果的生防菌,采用常规组织分离法对铁皮石斛感病植株叶片进行病原菌的分离培养,依据柯赫氏法则对病原菌进行致病型检测,并利用分子生物学技术结合形态学鉴定确定病原菌分类地位;此外,采用对峙培养方法,进行生防菌的筛选.结果表明,铁皮石斛圆斑病菌(编号YPE-SH9)的形态学特征与已报道的露湿漆斑菌(Myrothecium roridum)相符合;系统进化树分析表明,菌株YPESH9的rDNA-ITS与露湿漆斑菌(AJ301995,AJ302001)在同一个分支上,同源性达100%;铁皮石斛接种露湿漆斑菌后均发病,症状与田间自然发病相同,说明铁皮石斛圆斑病是由露湿漆斑菌引起.对峙培养试验结果发现,分离自铁皮石斛的内生真菌YPESH-1,对露湿漆斑菌菌丝生长有很好的抑制作用,并明确YPESH-1为尖孢镰孢菌(Fusarium oxysporum).

A disease survey conducted in DendrobiumofficinalePlantation in Puer city of Yunnan province indicated that the average incidence of round spot on D.officinale was 30%.In order to identify the pathogen causing round spot on D.officinale,and screen out the effective antagonistic strains against it,typical diseased samples were collected from Pu’er,Yunnan Province and leaf pieces were cultured on potato dextrose agar(PDA)medium plate under 28℃in dark to isolate the causal agent.Pathogenicity test,rDNA intergenic spacer(ITS)regions sequencing and analysis were conducted for pathogen identification of D.officinale round spot,and biocontrol bacteria,fungus and actinomycete against the round spot pathogen were screened with the inhibiting zone method.The results showed that the morphological features of the pathogen of D.officinale round spot(YPE-SH9)were similar to those of the reported Myrothecium roridum.The nucleotide sequence of the ITS region of isolate YPE-SH9shared 100%identity with the two M.roridumisolates(AJ301995and AJ302001).The phylogenetic tree based on the nucleotide sequence of the ITS region indicated they were clustered in the same group.Pathogenicity test results showed M.roridum could cause round spoton the inoculated D.officinale plants,the symptoms were similar to the diseased D.officinale plants in the field,which indicated that round spot on D.officinale was caused by M.roridum.One of the selected antagonistic strains,YPESH-1,showed satisfactory inhibition activities against the growth of M.roridum,and YPESH-1was identified to be Fusariumoxysporum.