辣椒疫病病株与健株根区土壤微生态研究

Micro-ecology in the Rhizosphere Soil of the Phytophthora Blight Infected Plants and Healthy Plants

对辣椒健株与病株根区土壤微生物区系特征及可培养微生物多样性进行比较,探索辣椒疫病发生的微生态机制。采用常规方法测定土壤养分,稀释涂平板法测定辣椒病、健株根区土细菌(B)、真菌(F)及放线菌(A)的数量,并对分离得到的细菌和放线菌进行16SrRNA序列分析,对真菌进行ITS序列分析,研究连作辣椒疫病病株与健株根区土微生态差异。结果显示,辣椒病株根区土中速效K、速效P、全N和有机质均高于健株;辣椒病株根区土中的微生物数量较健株发生较大变化,其中真菌数量增加388.9%。对从根区土中分离得到的可培养微生物进行分子鉴定,得到20株细菌,5株真菌和20株放线菌。16SrRNA序列分析表明,病株与健株根区土壤中共同存在的细菌只占总数的17.4%,放线菌占总数的16.7%,病株和健株根区土壤中优势细菌菌属和优势放线菌菌属都为芽孢杆菌属(Bacillus)和链霉菌属(Streptomyces)。病株根区土壤分离得到致病真菌尖刀廉孢菌(Fusarium oxysporum)和Plectosphaerella cucumerina。辣椒病株与健株根区土中微生物数量异常,种类变化是辣椒疫病发生的重要原因之一。

To explore the microbial ecological mechanism of pepper phytophthora blight by comparing the diversity of the culturable microorganisms between rhizosphere soils of infected and healthy plants.Normal method was used to measure the soil nutrition.Serial dilution and spread-plate techniques were applied to measure the counts of bacteria,fungi and actionmycete in the rhizosphere soils of infected and healthy plants.16 SrDNA sequence analysis was employed to identify bacteria and actionmycetes and ITS sequence analysis was used to identify fungi.The results showed that the contents of available P,K,total N and organic matter in rhizosphere soil of infected plants were higher than those of healthy plants.Compared to healthy plants,the colony counts of fungi were 388.9%higher in rhizosphere soil of infected plants.There were no differences of colony counts of bacteria and actinomycetes between infected and healthy plants.The isolated microorganisms were classified in 20 bacteria species,5fungi species and 20 actinomycete species.Out of the identified species,only 17.4%of bacteria,20% of fungi and 16.7% of actinomycete were common in both rhizosphere soils of infec-ted and healthy plants.Bacillus and Streptomyces were the dominant gunus of bacteria and actionmycete in both rhizosphere soils of infected and healthy plants.Pathogenic fungi Fusarium oxysporum and Rhizopus oryzae were obtained in the rhizosphere soil of the infected plants.The changes of counts and species of microorganisms in the rhizosphere soil is a main reason of pepper phytophthora blight.