Dazomet application suppressed watermelon wilt by the altered soil microbial community

Isolation of Antagonistic Endophytic Fungi from Postharvest Chestnuts and Their Biocontrol on Host Fungal Pathogens

In this study, antagonistic endophytic fungi were isolated from postharvest chestnut fruits; endophytic antagonistic fungi and their combination of inhibitory effects on the fungal pathogen Neofusicoccum parvum were evaluated. A total of 612 endophytic fungi were isolated from 300 healthy chestnut kernels, and 6 strains out of them including NS-3, NS-11, NS-38, NS-43, NS-56, and NS-58 were confirmed as antagonistic endophytic fungi against Neofusicoccum parvum; these were separately identified as Penicillium chermesinum, Penicillium italicum, Penicillium decaturense, Penicillium oxalicum, Talarmyces siamensis, and Penicillium guanacastense. Some mixed antagonistic endophytic fungi, such as NS-3-38, NS-11-38, NS-43-56, and NS-56-58-38, exhibited a much stronger antifungal activity against N. parvum than that applied individually. Among them, the mixture of NS-3-38 showed the highest antifungal activity, and the inhibition rate was up to 86.67%. The fermentation broth of NS-3, NS-38, and their combinations exhibited an obvious antifungal activity against N. parvum, and the ethyl acetate phase extract of NS-3-38 had the strongest antifungal activity, for which the inhibitory rate was up to 90.19%. The NS-3-38 fermentation broth combined with a chitosan coating significantly reduced N. parvum incidence in chestnuts from 100% to 19%. Furthermore, the fruit decay and weight loss of chestnuts during storage were significantly decreased by the NS-3-38 fermentation broth mixture along with a chitosan coating. Therefore, a mixture of P. chermesinum and P. decaturense could be used as a potential complex biocontrol agent to control postharvest fruit decay in chestnuts.

Salicylic acid remodeling of the rhizosphere microbiome induces watermelon root resistance against Fusarium oxysporum f. sp. niveum infection

Fusarium wilt disease poses a severe threat to watermelon cultivation by affecting the yield and quality of the fruit. We had previously found that the rhizosphere microbiome has a significant impact on the ability of watermelon plants to resist Fusarium wilt development and that salicylic acid (SA) is closely related to this phenomenon. Therefore, in this study, the role of SA as a mediator between plants and microbes in activating resistance against Fusarium oxysporum f. sp. niveum (FON) infection was explored through physiological, biochemical, and metagenomic sequencing experiments. We demonstrated that exogenous SA treatment could specifically increase some beneficial rhizosphere species that can confer resistance against FON inoculation, such as Rhodanobacter, Sphingomonas, and Micromonospora. Functional annotation analysis indicated that SA application significantly increased the relative abundance of glycoside hydrolase and polysaccharide lyase genes in the microbiome, which may play an essential role in increasing plant lipids. Moreover, network interaction analysis suggested that the highly expressed AAC6_IIC gene may be manipulated through SA signal transduction pathways. In conclusion, these results provide a novel strategy for controlling Fusarium wilt in watermelons from the perspective of environmental ecology, that is, by manipulating the rhizosphere microbiome through SA to control Fusarium wilt.

Driving factors of nitrogen conversion during chicken manure aerobic composting under penicillin G residue: Quorum sensing and its signaling molecules

This study explored effects of different concentrations of penicillin G on nitrogen conversion, bacterial community composition, and quorum sensing during chicken manure aerobic composting. After composting, adding penicillin G down-regulated the abundance of 71 genera and up-regulated the abundance of 103 genera. These bacterial genera were mainly Firmicutes and Proteobacteria. 16S rRNA gene sequencing was employed for function prediction, and the results showed that the addition of penicillin G increased nitrification, reduced denitrification. The autoinducer-1 (AI-1), autoinducer-3 (AI-3) and Phr signal molecules further participated in the nitrogen cycle by regulating the population behavior among multiple bacterial genera. In addition, SEM analysis showed that the quorum sensing system negatively regulated the abundance of genus related to the nitrogen conversion during chicken manure aerobic composting. This is a new theoretical analysis of the research on the treatment of hazardous materials.

Study on the Role of Salicylic Acid in Watermelon-Resistant Fusarium Wilt under Different Growth Conditions

BACKGROUND

Fusarium wilt disease is leading threat to watermelon yield and quality. Different cultivation cropping systems have been reported as safe and efficient methods to control watermelon Fusarium wilt. However, the role of salicylic acid (SA) in watermelon resistance to Fusarium wilt in these different cultivation systems remains unknown.

METHODS

in this experiment, we used RNA-seq and qRT-PCR to study the effect of SA biosynthesis on improving watermelon health, demonstrating how it may be responsible for Fusarium wilt resistance under continuous monocropping and oilseed rape rotation systems.

RESULTS

the results revealed that the expression of the CIPALs genes was key to SA accumulation in watermelon roots. We observed that the NPR family genes may play different roles in responding to the SA signal. Differentially expressed NPRs and WRKYs may interact with other phytohormones, leading to the amelioration of watermelon Fusarium wilt.

CONCLUSIONS

further understanding of gene expression patterns will pave the way for interventions that effectively control the disease.

Study on the Role of Phytohormones in Resistance to Watermelon Fusarium Wilt

Fusarium wilt disease is one of the major diseases causing a decline in watermelon yield and quality. Researches have informed that phytohormones play essential roles in regulating plants growth, development, and stress defendants. However, the molecular mechanism of salicylic acid (SA), jasmonic acid (JA), and abscisic acid (ABA) in resistance to watermelon Fusarium wilt remains unknown. In this experiment, we established the SA, JA, and ABA determination system in watermelon roots, and analyzed their roles in against watermelon Fusarium wilt compared to the resistant and susceptible varieties using transcriptome sequencing and RT-qPCR. Our results revealed that the up-regulated expression of Cla97C09G174770, Cla97C05G089520, Cla97C05G081210, Cla97C04G071000, and Cla97C10G198890 genes in resistant variety were key factors against (Fusarium oxysporum f. sp. Niveum) FON infection at 7 dpi. Additionally, there might be crosstalk between SA, JA, and ABA, caused by those differentially expressed (non-pathogen-related) NPRs, (Jasmonate-resistant) JAR, and (Pyrabactin resistance 1-like) PYLs genes, to trigger the plant immune system against FON infection. Overall, our results provide a theoretical basis for watermelon resistance breeding, in which phytohormones participate.

Fungicides alter the distribution and diversity of bacterial and fungal communities in ginseng fields

The present study was focused on comparison of four typical fungicides in ginseng field to evaluate the impact of the different fungicides on the soil bacterial and fungal communities’ composition and diversity by using high-throughput sequencing. Five treatments were designed comprising carbendazim (D), dimethyl disulfide (E), dazomet (M), calcium cyanamide (S), and control (C). The application of fungicide obviously altered the distribution of dominant fungal and bacterial communities and remarkably decreased the diversity (1099-763 and 6457-2245). The most abundant Proteobacteria obviously degenerate in fungicide-treated soil and minimum in E (0.09%) compared to control (25.72%). The relative abundance of Acidobacteria was reduced from 27.76 (C) to 7.14% after applying fungicide and minimum in E. The phylum Actinobacteria are both decomposers of organic matter and enemies of soil-borne pathogens, elevated from 11.62 to 51.54% and are high in E. The fungi community mainly distributed into Ascomycota that enriched from 66.09 to 88.21% and highin M and E (88.21 and 85.10%), and Basidiomycota reduced from 21.13 to 3.23% and low in M and E (5.27 and 3.23%). Overall, environmentally related fungicides decreased the diversity and altered the composition of bacterial and fungal communities, highest sensitivity present in dimethyl disulfide-treated soil.