ABSTRACT
Objective:To explore the differences in rhizosphere microbial community structure between <italic>Fusarium</italic> wilt-infected and healthy <italic>Chrysanthemum morifolium </italic>plants<italic>.</italic> Method:The rhizosphere soils of diseased and healthy<italic> C. morifolium </italic>plants were sampled and subjected to high-throughput 16S ribosomal DNA （rDNA） and internal transcribed spacer （ITS） sequencing， to identify the microbial community structure including bacteria and fungi. Result:<italic>Fusarium</italic> wilt reduced the bacterial abundance and diversity but had no significant effect on fungal alpha-diversity.The proportions of Acidobacteria， Gemmatimonadetes， and Nitrospirae in rhizosphere soil of healthy <italic>C.morifolium</italic> plants were higher than those of diseased plants， while the proportions of Proteobacteria and Bacteroidetes were lower（<italic>P</italic><0.05）. <italic>Fusarium</italic> fungi accounted for 27.49%， 14.53%， and 11.94% in diseased plants whereas 0.47%， 1.01%， and 0.67% in healthy plants.Pathogenic bacteria <italic>Pectobacterium</italic> and <italic>Dickeya</italic> were enriched in rhizosphere soil of diseased plants. The abundances of nitrifying， detoxifying， and photosynthetic bacteria in rhizosphere soil of healthy plants were higher than those of diseased plants. Conclusion:<italic>Fusarium</italic> wilt reduces the bacterial richness and diversity and triggers the enrichment of massive <italic>Fusarium</italic> fungi， <italic>Pectobacterium</italic>， and <italic>Dickeya</italic>. The proportion of beneficial bacteria in rhizosphere soil of healthy plants is significantly higher than that of diseased plants.
ABSTRACT
During the high-temperature and rainy season from June to October in 2017-2019,serious southern blight broke out in the Cynanchum stauntonii planting area in Tuanfeng county,Hubei province,which had a great impact on the yield and quality of medicinal materials. In this study,the pathogen of C. stauntonii was isolated,purified,and identified,and the pathogenicity was tested according to Koch's postulates. Meanwhile,the biological characteristics of the pathogen were analyzed. On this basis,the effective fungicides were screened in laboratory. Finally,the pathogen( BQ-1) was identified as Athelia rolfsii( Deuteromycotina,Basidiomycota,anamorph: Sclerotium rolfsii). The optimum growth conditions for BQ-1 were 25-30 ℃,p H 5-8,and alternating light and dark.The effective chemical fungicides were lime-sulphur-synthelic-solution( LSSS) and flusilazole,and the effective botanical fungicide was osthole. BQ-1 was highly homologous to the pathogen HS-1 of peanut southern blight,with the similarity of 18 S r DNA and TEF sequences at 99. 09%. The southern blight in C. stauntonii might be resulted from that in peanut. In the production of C. stauntonii,the following measures should be taken: avoiding rotation or neighboring with peanut,draining water from June to October to reduce humidity,and reasonably applying fungicides.
Subject(s)
Basidiomycota , Cynanchum , Fungicides, Industrial/pharmacology , HumidityABSTRACT
In order to identify the species and biological characteristics of the pathogen of southern blight from three kinds of Chinese medicine of Iridaceae(Belamcanda chinensis, Iris tectorum and I. japonica) in Dabie Mountains, the isolation, identification, pathogenicity and biological characteristics of the pathogens were studied according to Koch's postulates. In addition, 9 chemical fungicides, 3 botanical fungicides and 5 microbial fungicides were used to evaluate their inhibition to the isolates in vitro. The results showed that all the strains(SG-Q, YW-Q, and HDH-Q) isolated and purified from the diseased plants of B. chinensis, I. tectorum and I. japonica, respectively, were identified as Sclerotium rolfsii through morphological observation and sequence aligement of 18 S rDNA, rDNA-ITS and TEF. Field observations showed that the intensity of the disease incidence of three Iridaceae plants was B. chinensis>I. japonica> I. tectorum, and the pathogenicity of the strains was SG-Q>YW-Q>HDH-Q. For biological characteristics, SG-Q strain was suitable for growth under the 12 h light/12 h dark cycle, with the optimal growth temperature of 30 ℃ and pH of 5. Among the 9 tested chemical fungicides, 29% lime sulphure and 10% flusilazole had stronger inhibitory effect on mycelia growth of SG-Q. For 3 botanical fungicides, 1% osthol, 20% eugenol and 0.5% berberine could effectively inhibt the mycelial growth of SG-Q and cause the morphological variation of the pathogen. For 5 microbial fungicides, Trichoderma harzianum and Bacillus subtilis had better inhibition on the mycelium growth of SG-Q.