AUTHOR=Chen Jun , Wu Linkun , Xiao Zhigang , Wu Yanhong , Wu Hongmiao , Qin Xianjin , Wang Juanying , Wei Xiaoya , Khan Muhammad U. , Lin Sheng , Lin Wenxiong 

TITLE=Assessment of the Diversity of Pseudomonas spp. and Fusarium spp. in Radix pseudostellariae Rhizosphere under Monoculture by Combining DGGE and Quantitative PCR

JOURNAL=Frontiers in Microbiology

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2017.01748

DOI=10.3389/fmicb.2017.01748

ISSN=1664-302X

ABSTRACT=<p><italic>Radix pseudostellariae</italic> is a perennial tonic medicinal plant, with high medicinal value. However, consecutive monoculture of this plant in the same field results in serious decrease in both yield and quality. In this study, a 3-year field experiment was performed to identify the inhibitory effect of growth caused by prolonged monoculture of <italic>R. pseudostellariae</italic>. DGGE analysis was used to explore the shifts in the structure and diversity of soil <italic>Fusarium</italic> and <italic>Pseudomonas</italic> communities along a 3-year gradient of monoculture. The results demonstrated that extended monoculture significantly boosted the diversity of <italic>Fusarium</italic> spp., but declined <italic>Pseudomonas</italic> spp. diversity. Quantitative PCR analysis showed a significant increase in <italic>Fusarium oxysporum</italic>, but a decline in <italic>Pseudomonas</italic> spp. Furthermore, abundance of antagonistic <italic>Pseudomonas</italic> spp. possessing antagonistic ability toward <italic>F. oxysporum</italic> significantly decreased in consecutively monocultured soils. Phenolic acid mixture at the same ratio as detected in soil could boost mycelial and sporular growth of pathogenic <italic>F. oxysporum</italic> while inhibit the growth of antagonistic <italic>Pseudomonas sp</italic>. CJ313. Moreover, plant bioassays showed that <italic>Pseudomonas</italic> sp. CJ313 had a good performance that protected <italic>R. pseudostellariae</italic> from infection by <italic>F. oxysporum.</italic> In conclusion, this study demonstrated that extended monoculture of <italic>R. pseudostellariae</italic> could alter the <italic>Fusarium</italic> and <italic>Pseudomonas</italic> communities in the plant rhizosphere, leading to relatively low level of antagonistic microorganisms, but with relatively high level of pathogenic microorganisms.</p>