Genomic survey of NPF and NRT2 transporter gene families in five inbred maize lines and their responses to pathogens infection.

Besides manipulating nitrate uptake and allocation, nitrate transporters (NRTs) are also known to play crucial roles in pathogen defense and stress response. By blasting with the model NRT genes of poplar and Arabidopsis, a total of 408 gene members were identified from 5 maize inbred lines in which the number of NRTs ranged from 72 to 88. Phylogenetic analysis showed that the NRT genes of maize were classified into NRT1/PTR (NPF), NRT2 and NRT3 subfamilies, respectively. Marked divergence of the duplication patterns of NRT genes were identified, which may be a new basis for classification and identification of maize varieties. In terms of biotic stress, NRT2.5A showed an enhanced expression during the pathogen infection of Colletotrichum graminicola, while NRT1c4C was down-regulated, suggesting that maize NRT transporters may have both positive and negative roles in the disease resistance response. This work will promote the further studies of NRT gene families in maize, as well as be beneficial for further understanding of their potential roles in plant-pathogen interactions.

Enhancing wuyiencin productivity of Streptomyces albulus (CK15) by mutagenesis breeding with atmospheric and room temperature plasma.

Streptomyces species are known for their ability to efficiently produce secondary metabolites, including various antibiotics. Wuyiencin, an antibiotic produced by Streptomyces albulus CK15, is commonly used in agriculture to control fungal diseases in crops and vegetables. In this study, we utilized atmospheric and room temperature plasma (ARTP) mutagenesis to generate mutant S. albulus strains with improved fermentation capabilities for wuyiencin production. After mutagenizing the wild-type S. albulus CK15 strain once and conducting two rounds of antimicrobial screening, three genetically stable mutants (M19, M26, and M28) were identified. These mutants showed increased wuyiencin production by 17.4%, 13.6%, and 18.5% in comparison to the CK15 strain in flask culture, respectively. The M28 mutant exhibited the highest wuyiencin activity, producing 1443.0 ± 134.6 U/mL in flask culture and 1673.8 ± 127.4 U/mL in a 5 L fermenter. These results demonstrate that ARTP is an efficient tool for microbial mutation breeding and improving wuyiencin production.

Effect of toyF on wuyiencin and toyocamycin production by Streptomyces albulus CK-15.

Streptomyces albulus CK-15 produces various secondary metabolites, including the antibiotics wuyiencin and toyocamycin, which can reportedly control a broad range of plant fungal diseases. The production of these nucleoside antibiotics in CK-15 is regulated by two biosynthesis gene clusters. To investigate the potential effect of toyocamycin biosynthesis on wuyiencin production, we herein generated S. albulus strains in which a key gene in the toyocamycin biosynthesis gene cluster, namely toyF, was either deleted or overexpressed. The toyF deletion mutant ∆toyF did not produce toyocamycin, while the production of wuyiencin increased by 23.06% in comparison with that in the wild-type (WT) strain. In addition, ΔtoyF reached the highest production level of wuyiencin 4 h faster than the WT strain (60 h vs. and 64 h). Further, toyocamycin production by the toyF overexpression strain was two-fold higher than by the WT strain, while wuyiencin production was reduced by 29.10%. qRT-PCR showed that most genes in the toyocamycin biosynthesis gene cluster were expressed at lower levels in ∆toyF as compared with those in the WT strain, while the expression levels of genes in the wuyiencin biosynthesis gene cluster were upregulated. Finally, the growth rate of ∆toyF was much faster than that of the WT strain when cultured on solid or liquid medium. Based on our findings, we report that in industrial fermentation processes, ∆toyF has the potential to increase the production of wuyiencin and reduce the timeframe of fermentation.

iTRAQ-based proteomic analysis reveals the mechanisms of Botrytis cinerea controlled with Wuyiencin.

BACKGROUND: Grey mould is an important plant disease worldwide, caused by Botrytis cinerea, resulting in serious economic loss. Wuyiencin, a low toxicity, high efficiency, and broad-spectrum agricultural antibiotic, has been demonstrated effectiveness against B. cinerea. RESULTS: Wuyiencin treatment inhibited growth and sporulation of B. cinerea, specifically altering hypha morphology and intracellular structures. These changes were accompanied by differential expression (fold change > 2.0) of 316 proteins identified by iTRAQ-labelling LC-MS/MS analysis (P < 0.05). Up-regulation of 14 proteins, including carbohydrate metabolism proteins and cell wall stabilization proteins, was validated by parallel reaction monitoring (PRM). Down-regulation of 13 proteins was validated by PRM, including regulators of energy metabolism, nucleotide/protein synthesis, and the biosynthesis of mediators of plant stress and decay. CONCLUSION: Our results confirm the inhibitory biological effects of wuyiencin on B. cinereal and elaborate on the differentially expressed proteins and associated pathways implicated in the capacity of wuyiencin to debilitate the growth and pathogenicity of grey mould. This study provides validated candidates for further targeted exploration with the goal of optimizing wuyiencin as a safe, low-toxicity agent for biological control.

Heterogeneity Analysis of the Effects of Haze Pollution on the Health of Left-Behind Children in Urban and Rural Areas in China.

Differences in economic development, public services, production, and lifestyle between urban and rural areas lead to significant differences in people's attitudes and abilities to cope with environmental pollution. Furthermore, environmental pollution has heterogeneous effects on the health of individuals in urban and rural areas. The article takes the health of left-behind children as an entry point to analyze the impact of haze pollution on the health of urban and rural left-behind children. Using children's survey data from the China Health and Nutrition Survey and the urban and rural raster PM2.5 data from 2000 to 2015, this study applies a logit model to analyze the heterogeneity of the impact of haze pollution on the health of left-behind children. This research finds that, first, the health effects of haze pollution on rural left-behind children are more severe than those on rural children not left behind. Moreover, the same results are not present in the sample of urban left-behind children. Second, the health of left-behind children is more vulnerable to haze pollution than the others when neither parent is at home in rural areas. Third, no evidence proves that haze pollution has more severe health effects on rural children aged 0-6 years with parents away from home. Meanwhile, haze pollution will more easily influence the health status of left-behind children aged 7 years and above in rural areas due to their parents' absence. Fourth, the finding that haze pollution significantly affects the health of left-behind children with parents away from home only applies to the central and western rural samples in China.

Genome-wide transcriptomic analysis of the response of Botrytis cinerea to wuyiencin.

Grey mould is caused by the ascomycetes Botrytis cinerea in a range of crop hosts. As a biological control agent, the nucleoside antibiotic wuyiencin has been industrially produced and widely used as an effective fungicide. To elucidate the effects of wuyiencin on the transcriptional regulation in B. cinerea, we, for the first time, report a genome-wide transcriptomic analysis of B. cinerea treated with wuyiencin. 2067 genes were differentially expressed, of them, 886 and 1181 genes were significantly upregulated and downregulated, respectively. Functional categorization indicated that transcript levels of genes involved in amino acid metabolism and those encoding putative secreted proteins were altered in response to wuyiencin treatment. Moreover, the expression of genes involved in protein synthesis and energy metabolism (oxidative phosphorylation) and of those encoding ATP-binding cassette transporters was markedly upregulated, whereas that of genes participating in DNA replication, cell cycle, and stress response was downregulated. Furthermore, wuyiencin resulted in mycelial malformation and negatively influenced cell growth rate and conidial yield in B. cinerea. Our results suggest that this nucleoside antibiotic regulates all aspects of cell growth and differentiation in B. cinerea. To summarize, some new candidate pathways and target genes that may related to the protective and antagonistic mechanisms in B. cinerea were identified underlying the action of biological control agents.

Identification of wysPII as an Activator of Morphological Development in Streptomyces albulus CK-15.

Wuyiencin is produced by Streptomyces albulus var. wuyiensis and used widely in agriculture to control a variety of fungal diseases, such as cucumber downy mildew, strawberry powdery mildew, and tomato gray mold. As an industrially-produced biopesticide, reducing production costs is very important for popularization of this approach. To obtain a rapidly growing strain that effectively shortens the fermentation time, we investigated the effects of knockout and overexpression of the wysPII gene, a member of the LuxR regulatory gene family, in S. albulus strain CK-15. The ΔwysPII mutant exhibited a reduced rate of growth and sporulation. The time taken to reach the greatest mycelial biomass was approximately 18 h shorter in the ooPII (wysPII overexpressing) strain compared with that of the wild-type (WT) strain. In addition, the time to reach the greatest wuyiencin production was 56 h in the ooPII strain compared with 62 h in the WT strain. Furthermore, wysPII was shown to act as an activator of morphological development without affecting wuyiencin production. Thus, the ooPII strain can be used to reduce costs and increase efficiency in industrial fermentation processes for wuyiencin production.