Effect of treatments on bacterial wilt of ginger at high mountain area and soil bacterial community

Abstract:

[Background] Fengtou ginger is the famous national geographic hallmark product in Laifeng county in Western mountain of Hubei. Its cultural area was up to 3 400 hm2; however, due to the prevalence of bacterial wilt of ginger and without effective control methods, the cultural area is falling to current 740 hm2. The bacterial wilt of ginger has become the key factor restricting the industrial development of Fengtou ginger. [Objective] In order to study the control of bacterial wilt of Fengtou ginger at high mountain and the impacts on soil microbial ecology of high mountain. [Methods] Through field experiments, the control effects of five treatments on bacterial wilt of Fengtou ginger were evaluated, including soil disinfection with dazomet (T1), root drenching with bio-control microbial strain 34107 (T2), soil disinfection combined with bio-control (T3), and root drenching with Zhongshengmycin (T4), and control (T5). Meantime, the soil genomic DNA in above treatments were extracted for high-through-put sequencing of V3–V4 regions of bacterial 16S rRNA gene by Illumina MiSeq platform. [Results] Among these treatments, the control effect of T3 on bacterial wilt of Fengtou ginger was the best (96.1%), which was greater than T1 (86.5%) and significantly greater than T2 (75.2%) and T4 (54.8%). The yield and economic profit of T3 were the most notable, followed by T1, T2 and T4, whereas that of T5 were the lowest and its economic profit was negative. High-through-put sequencing obtained 608 070 high-quality sequences of 16S rRNA gene, which were assembled into 9 243 OTU; The bacterial community structures at phylum level in different treatments were quite similar, while the abundance of a part of OTUs had greater changes. Analysis of soil bacterial alpha diversity indexes demonstrated that Shannon and Simpson indexes in T1 to T4 were significantly greater than T5 (P<0.05), while except for T2, the Chao1 indexes in the rest were significantly greater than T5 (P<0.05); The ACE index of T3 was the greatest, greater than T1 and T4 and significantly greater than T2 and T5 (P<0.05). Compared to T5, the total 25 OTUs at phylum level were significantly changed (P<0.05), and most of them were increased in abundance; the total 159 OTUs at genus level were significantly changed (P<0.05), of which 50.9% were common in all four treatments and only a few were detected in single treatment. Among top 10 most abundant genera, the genera Ralstonia and Pectobacterium containing plant pathogens were significantly downregulated (P<0.05), while beneficial bacteria, such as Gemmatimonas and Jatrophihabitans, were upregulated at different scales. The OTUs of soil bacteria were mapped to 6 055 KEGG functional pathways, of which the functional pathways related to nitrite reductase were significantly downregulated (P<0.05), the pathways related to nitrogen fixation were upregulated at different scales, and the pathway related to nitrous oxide reductase were downregulated in T3 and T4 but upregulated in T1 and T2. The KEGG pathways were enriched into 41 metabolic pathway modules, of which the abundance of the modules related to amino acid and carbohydrate metabolism were the greatest, and most were the highest in T3. [Conclusion] Dazomet soil disinfection combined with bio-control using strain 34107 was able to effectively control bacterial wilt of Fengtou ginger at high mountain, and it also can increase the microbial diversity of soil bacteria and was benefit to recovery and restoration of soil microbial ecology.