Purpose

Root inoculation of plants with beneficial microorganisms promotes plant growth and improves tolerance to biotic and abiotic stresses. In banana plants, microbial inoculation has shown promising effects on plant growth, but the effect on foliar diseases and on the resident native microbial community is yet unknown. We examined the effects of Bacillus subtilis EA-CB0575 introduced on roots of micropropagated banana plants on black Sigatoka disease and on the root microbiome.

Methods

In vitro banana seedlings were root-inoculated with strain EA-CB0575, and then treated with the foliar pathogen Pseudocercospora fijiensis. Root bacterial communities were characterized using 16S rRNA gene sequencing, before and after pathogen inoculation; and the severity of the disease was determined.

Results

Inoculation of strain EA-CB0575 on in vitro banana roots provided a reduction in the severity of black Sigatoka disease in greenhouse. This inoculation induced changes in the composition of the bacterial root microbiome, changes that arose from amplicon sequence variants (ASVs) of low abundances. Differential abundance analysis of ASV indicated that prior pathogen inoculation significantly more enriched sequences were identified in roots treated with EA-CB0575 (191-ASVs) compared to control plants (73-ASVs), but after pathogen inoculation more sequences were found in control (277-ASVs) than bacterial inoculated plants (60-ASVs). Furthermore, in vitro banana roots host a bacterial community that differ from that of greenhouse plants.

Conclusion

Results suggest that banana plants inoculated with B. subtilis EA-CB0575, reshape the composition of the bacterial community in a P. fijiensis dependent manner and induce systemic resistance protecting plants against black Sigatoka.

中文翻译：

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枯草芽孢杆菌 EA-CB0575 接种微繁香蕉植物抑制黑斑病并诱导根部微生物组的变化

目的

植物根部接种有益微生物可促进植物生长并提高对生物和非生物胁迫的耐受性。在香蕉植物中，微生物接种已显示出对植物生长的良好影响，但对叶面病害和居民原生微生物群落的影响尚不清楚。我们检查了在微繁香蕉植物根部引入的枯草芽孢杆菌EA-CB0575 对黑色 Sigatoka 病和根部微生物组的影响。

方法

用菌株EA-CB0575对体外香蕉幼苗进行根部接种，然后用叶面病原体Pseudocercospora fijiensis进行处理。在病原体接种前后，使用 16S rRNA 基因测序对根系细菌群落进行了表征；并确定了疾病的严重程度。

结果

在体外香蕉根上接种菌株 EA-CB0575 可降低温室中黑叶斑病的严重程度。这种接种引起了细菌根微生物组组成的变化，这些变化是由低丰度的扩增子序列变体 (ASV) 引起的。ASV 的差异丰度分析表明，与对照植物 (73-ASV) 相比，在用 EA-CB0575 (191-ASV) 处理的根中鉴定出先前的病原体接种显着更丰富的序列，但在病原体接种后，在对照中发现了更多的序列 (277 -ASVs) 高于细菌接种植物 (60-ASVs)。此外，体外香蕉根部的细菌群落与温室植物不同。

结论

结果表明，接种B. subtilis EA-CB0575 的香蕉植物以P. fijiensis依赖的方式重塑了细菌群落的组成，并诱导了保护植物免受黑色 Sigatoka 的系统抗性。