Search

Plant endophytic microbial communities consist of many latent plant pathogens and, also, many pathogen-related species with reduced virulence. Though with a long history of co-evolution, the diversity and composition of the endophytic mycobiota, especially the pathogen-related fungal groups, has been under-investigated in Citrus (C.). Based on the amplicon sequencing of fungal internal transcribed spacer (ITS), the leaf endophytic mycobiota were profiled on citrus varieties from different citrus-producing regions. The pomelo variety shared significantly distinctive leaf mycobiota when compared to the mandarin and sweet orange; these conform to their host genetic relationships. In addition, a data set of 241 citrus-related fungi, including 171 (71%) pathogens and potential pathogens, was summarized from previous studies. Under the criteria of local BLAST (covered ITS nucleotide ≥ 150 bp, sequence identity ≥ 99%), a total of 935 fungal operational taxonomic units (OTUs) were assigned to 62 pathogen-related fungal groups, representing 14.9% of the relative abundance in the whole community. Of which, the top groups consisted of Colletotrichum gloeosporioides (mean relative abundance, 4.3%), Co. citricola and Co. karstii (2.7%), Zasmidium citri-griseum (2.4%), and Z. fructigenum (1.4%). At the genus level, the ratio of the pathogen-related fungal groups in 64% of fungal genera (16 out of 25) exceeded 50%, which are the solely or mainly occurring fungi of their genus in citrus. Our study suggests that the leaf endophytic compartment may be an important place for the growth of latent pathogens. [ABSTRACT FROM AUTHOR]

For perennial plants, newly emerged organs are fresh hot spots for environmental microbes to occupy and assemble to form mature microbial communities. In the microbial community, some commensal fungi can play important roles in microbial succession, thus significantly improving host plant growth and disease resistance. However, their participating patterns in microbial assembly and succession remain largely unknown. In this study, we profiled the fungal community and found a similar fungal succession pattern of spring-emerged leaves from March to October in two pomelo orchards. Specifically, the fungal species, tracked on the old leaves, dominated the spring leaves after emergence and then decreased in relative abundance. This reduction in priority effects on the spring leaves was then followed by an increase in the number of observed species, Shannon and phylogenetic diversity indices, and the pathogen-associated fungal groups. In addition, we found that the temporal fungal succession on the spring leaves highly correlated with the disease occurrence in the orchards and with the temperature and precipitation variation from spring to summer. Of the pathogen-associated fungal groups, an increase in the relative abundance of Mycosphaerellaceae, hosting the causal agent of citrus greasy spot, correlated with the occurrence of the disease, while the relative abundance of Diaporthaceae, hosting the causal agent of melanose, was extremely low during the fungal succession. These results confirm that the two kinds of pathogen-associated fungal groups share different lifestyles on citrus, and also suggest that the study of temporal fungal succession in microbial communities can add to our understanding of the epidemiology of potential plant pathogens. [ABSTRACT FROM AUTHOR]

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The impact of oxygen impurity on phase relationships in the Zr-Mo-Fe system (Zr > 30 at.%) at 1000 °C was investigated by means of x-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy analysis. An oxygen-stabilized ternary compound γ-Zr2(Mo,Fe), derived from Ti2Ni type Zr4Fe2O, with cell parameter of a = 1.2213 nm was observed to be present in the investigated Zr-Mo-Fe alloys. The phase relationships of the Zr-Mo-Fe (O) system at 1000 °C in the Zr-rich corner consist of 3 four-phase regions, i.e., [βZr + λ-Zr(Mo,Fe)2 + γ-Zr2(Mo,Fe) + ZrMo2], [βZr + λ-Zr(Mo,Fe)2 + γ-Zr2(Mo,Fe) + Liquid], and [λ-Zr(Mo,Fe)2 + γ-Zr2(Mo,Fe) + Liquid + ZrFe2]. The previously detected Zr9Mo4Fe compound was not observed in this work. [ABSTRACT FROM AUTHOR]

Accurate composition-dependent interdiffusion coefficients, modulus and hardness data are important for the design of biomedical Ti alloys. Three groups of body-centered cubic (bcc) Ti-Mo-Zr diffusion couples annealed at 1273 K for 7 d were experimentally prepared, and their composition gradients were determined by using the electron probe microanalysis (EPMA). The composition-dependent interdiffusion coefficients of Ti-Mo-Zr alloys were calculated by using a pragmatic numerical inverse method and Matano-Kirkaldy method. Subsequently, nanoindentation technique combined with the reverse analysis algorithms and Oliver-Pharr method was utilized to obtain the mechanical properties of the ternary diffusion couples. Finally, other property data including indirect wear resistance parameters, bulk modulus, and shear modulus were discussed. The composition-dependent mechanical property database of bcc Ti-Mo-Zr system can offer a guide for the design of Ti alloys. [ABSTRACT FROM AUTHOR]

Background: Organic mulch is an important management practice in agricultural production to improve soil quality, control crop pests and diseases and increase the biodiversity of soil microecosystem. However, the information about soil microbial diversity and composition in litchi plantation response to organic mulch and its attribution to litchi downy blight severity was limited. This study aimed to investigate the effect of organic mulch on litchi downy blight, and evaluate the biodiversity and antimicrobial potential of soil microbial community of litchi plantation soils under organic mulch. Results: Organic mulch could significantly suppress the disease incidence in the litchi plantation, and with a reduction of 37.74% to 85.66%. As a result of high-throughput 16S rRNA and ITS rDNA gene illumine sequencing, significantly higher bacterial and fungal community diversity indexes were found in organic mulch soils, the relative abundance of norank f norank o Vicinamibacterales, norank f Vicinamibacteraceae, norank f Xanthobacteraceae, Unclassified c sordariomycetes, Aspergillus and Thermomyces were significant more than that in control soils. Isolation and analysis of antagonistic microorganism showed that 29 antagonistic bacteria strains and 37 antagonistic fungi strains were unique for mulching soils. Conclusions: Thus, we believe that organic mulch has a positive regulatory effect on the litchi downy blight and the soil microbial communities, and so, is more suitable for litchi plantation. [ABSTRACT FROM AUTHOR]

Background: Organic mulch is an important management practice in agricultural production to improve soil quality, control crop pests and diseases and increase the biodiversity of soil microecosystem. However, the information about soil microbial diversity and composition in litchi plantation response to organic mulch and its attribution to litchi downy blight severity was limited. This study aimed to investigate the effect of organic mulch on litchi downy blight, and evaluate the biodiversity and antimicrobial potential of soil microbial community of litchi plantation soils under organic mulch. Results: Organic mulch could significantly suppress the disease incidence in the litchi plantation, and with a reduction of 37.74% to 85.66%. As a result of high-throughput 16S rRNA and ITS rDNA gene illumine sequencing, significantly higher bacterial and fungal community diversity indexes were found in organic mulch soils, the relative abundance of norank f norank o Vicinamibacterales, norank f Vicinamibacteraceae, norank f Xanthobacteraceae, Unclassified c sordariomycetes, Aspergillus and Thermomyces were significant more than that in control soils. Isolation and analysis of antagonistic microorganism showed that 29 antagonistic bacteria strains and 37 antagonistic fungi strains were unique for mulching soils. Conclusions: Thus, we believe that organic mulch has a positive regulatory effect on the litchi downy blight and the soil microbial communities, and so, is more suitable for litchi plantation. [ABSTRACT FROM AUTHOR]