Control of Streptomyces alfalfae XY25 T Over Clubroot Disease and Its Effect on Rhizosphere Microbial Community in Chinese Cabbage Field Trials.

Yunxiang Liang,Xian Xia,Yuanliang Hu,Shuanglian Xiong,Lu Qiu,Zongjie Zhang,Kai Liu,Yongmei Hu,Shumiao Zhao,Zhuqing Zhao

doi:10.3389/fmicb.2021.641556

Yunxiang Liang, Xian Xia + Show 8 more

Open Access

https://doi.org/10.3389/fmicb.2021.641556

Copy DOI

Abstract

Clubroot caused by Plasmodiophora brassicae is one of the most destructive diseases in cruciferous crops. Streptomyces alfalfae XY25T, a biological control agent, exhibited great ability to relieve clubroot disease, regulate rhizosphere bacterial and fungal communities in Chinese cabbage, and promote its growth in greenhouse. Therefore, field experiments were carried out to investigate the effects of S. alfalfae XY25T on clubroot and rhizosphere microbial community in Chinese cabbage. Results showed that the control efficiency of clubroot by S. alfalfae XY25T was 69.4%. Applying the agent can alleviate soil acidification; increase the contents of soil organic matter, available nitrogen, available phosphorus, and available potassium; and enhance activities of invertase, urease, catalase, and alkaline phosphatase. During Chinese cabbage growth, bacterial diversity decreased first and then increased, and fungal diversity decreased gradually after inoculation with S. alfalfae XY25T. High-throughput sequencing analysis showed that the main bacterial phyla were Proteobacteria, Bacteroidetes, Acidobacteria, and Planctomycetes, and the major fungal phyla were Ascomycota and Basidiomycota in rhizosphere soil. The dominant bacterial genera were Flavobacterium, Candidatus, Pseudomonas, Stenotrophomonas, Sphingomonas, Flavisolibacter, and Gemmatimonbacteria with no significant difference in abundance, and the major fungal genera were Monographella, Aspergillus, Hypocreales, Chytridiaceae, Fusarium, Pleosporales, Agaricales, Mortierella, and Pleosporales. The significant differences were observed among Pleosporales, Basidiomycota, Colletotrichum, two strains attributed to Agaricales, and another two unidentified fungi by using S. alfalfae XY25T. Moreover, quantitative real-time PCR results indicated that P. brassicae content was significantly decreased after the agent inoculation. In conclusion, S. alfalfae XY25T can affect rhizosphere microbial communities; therefore, applying the agent is an effective approach to reduce the damage caused by clubroot.

Highlights

Cruciferous plants are widely planted worldwide and occupy an important position in agricultural production (Botero et al, 2019)
Statistical analysis results showed that the soil acidification trend was significantly alleviated by the application of S. alfalfae XY25T (Figure 1A)
These results showed that the diversity of fungi in the rhizosphere soil was significantly reduced after the application of S. alfalfae XY25T

Summary

Introduction

Cruciferous plants are widely planted worldwide and occupy an important position in agricultural production (Botero et al, 2019). Rotation, applying chemical agents such as cyclophosphamide, and breeding resistant varieties can inhibit the spore vitality of P. brassicae and reduce the occurrence of clubroot disease (Peng et al, 2014; Yang et al, 2020). These methods can only alleviate crop clubroot disease, but not completely eliminate it; the residue of chemical agents will endanger food safety and human health (Lee et al, 2008; Kowata-Dresch and May-De Mio, 2012; Botero et al, 2019; Mehraj et al, 2020).

Methods

Results

Conclusion