西北地区马铃薯疮痂病病原菌鉴定及其生物学特性

为明确西北地区马铃薯疮痂病病原菌的种类和生物学特性,分别采用常规组织分离法和土壤混悬液分离法从宁夏、陕西和甘肃3个省区采集的29份疮痂病发病薯块和8份发病地块土壤中进行病原菌分离,并利用形态特征、生理生化特性和16S rDNA序列分析对病原菌进行鉴定。结果表明,从发病薯块和发病土壤中共分离到50株链霉菌Streptomyces spp.,通过回接法验证获得6株马铃薯疮痂病致病菌株。6株致病菌株的培养特性和形态特征差别较大;其中菌株G4-1、G9和SYN13不能以果糖和木糖为单一碳源,菌株SYNT3不能以棉子糖为单一碳源;除菌株NLG4-1外,其余5株菌株均能在络氨酸琼脂培养基上产生黑色素。经16S rDNA序列分析,菌株G4-1、G9与疮痂病链霉菌S. scabiei的相似率分别达99.47%和99.34%,菌株NLG4-1、SYNT3与S. enissocaesilis的相似率分别达97.90%和98.18%,菌株GBH2与加利利链霉菌S. galilaeus的相似率达99.93%,菌株SYN13与S. turgidiscabies的相似率达97.56%,表明西北地区马铃薯疮痂病病原菌至少存在4个种。

Biological characterization and identification of the pathogens of potato scab in northwestern China

To clarify the species and biological characteristics of the pathogenic bacteria of potato scab disease in northwestern China, the pathogens were isolated from 29 samples of pathogenic potato chips and eight samples of pathogenic soil collected from Ningxia, Shaanxi and Gansu provinces with conventional tissue separation and soil suspension separation, and the pathogens were identified with biological, physiological and biochemical characteristics and 16S rDNA sequence analysis. The results showed that 50 strains of Streptomyces were isolated from the pathogenic potato and soil, and six were obtained by reattachment test. The cultural characteristics and morphological features of the six pathogenic strains were quite different. Among them, D-fructose and D-xylose could not be used as a single carbon source for strains G4-1, G9 and SYN13. Strain SYNT3 could not use raffinose as single carbon source. All the five strains except NLG4-1 could produce melanin in the Tyrosine-agar. According to 16S rDNA sequence analysis, the similarity rates of strains G4-1 and G9 with S. scabiei were 99.47% and 99.34%, respectively; the similarity rates of strains NLG4-1 and SYNT3 with S. enissocaesilis reached 97.90% and 98.18%, respectively; the similarity of the strain GBH2 with S. galilaeus was 99.93%, and the similarity of the strain SYN13 with S. turgidiscabies was 97.56%. It indicated that there were at least four species of pathogenic bacteria of potato scab disease in northwestern China.