The segmentation and classification of leaves in plant images are a great challenge, especially when several leaves are overlapping in images with a complicated background. In this paper, the ...segmentation and classification of leaf images with a complicated background using deep learning are studied. First, more than 2500 leaf images with a complicated background are collected and artificially labeled with target pixels and background pixels. Two-thousand of them are fed into a Mask Region-based Convolutional Neural Network (Mask R-CNN) to train a model for leaf segmentation. Then, a training set that contains more than 1500 training images of 15 species is fed into a very deep convolutional network with 16 layers (VGG16) to train a model for leaf classification. The best hyperparameters for these methods are found by comparing a variety of parameter combinations. The results show that the average Misclassification Error (ME) of 80 test images using Mask R-CNN is 1.15%. The average accuracy value for the leaf classification of 150 test images using VGG16 is up to 91.5%. This indicates that these methods can be used to segment and classify the leaf image with a complicated background effectively. It could provide a reference for the phenotype analysis and automatic classification of plants.
The problem of food spoilage due to
(
) needs to be resolved. In this study, we found that the minimum inhibitory concentration of cinnamaldehyde (CA) that inhibited
was 0.065 mg/ml and that corn can ...be prevented from spoiling at a concentration of 0.13 mg/cm
. In addition to inhibiting spore germination, mycelial growth, and biomass production, CA can also reduce ergosterol synthesis and can cause cytomembrane damage. Our intention was to elucidate the antifungal mechanism of CA. Flow cytometry, fluorescence microscopy, and western blot were used to reveal that different concentrations of CA can cause a series of apoptotic events in
, including elevated Ca
and reactive oxygen species, decrease in mitochondrial membrane potential (Δψ
), the release of cytochrome c, the activation of metacaspase, phosphatidylserine (PS) externalization, and DNA damage. Moreover, CA significantly increased the expression levels of apoptosis-related genes (
,
,
,
,
, and
). In summary, our results indicate that CA is a promising antifungal agent for use in food preservation.
Candida albicans
invasion is one of the most serious fungal infections in clinical history. In recent years, because of the widespread use of immunosuppressive drugs, chemotherapy drugs, ...glucocorticoids, and broad-spectrum antibiotics, serious drug resistance has been reported; therefore, a new type of antifungal drug needs to be developed. In this study, we found that Nerol (NEL) had strong antimicrobial activity and 0.77 μL/mL NEL was the minimum inhibitory concentration (MIC) effective against
C. albicans
. We determined the change of the growth curve of NEL for
C. albicans
, to identify the trend of NEL activity against
C. albicans
. Through the determination of the ergosterol content and glucose-induced extracellular fluid acidification of NEL on
C. albicans
, we found that NEL inhibits the growth of
C. albicans
by destroying cell membranes. This finding was also supported by the expression of SAP (secreted aspartyl proteinase) involved in cell membrane synthesis. Finally, demonstrations of phenotype investigation, colony-forming unit (CFU) counts, and PAS (periodic acid-Schiff) staining were conducted to prove that NEL had the ability to treated mouse oral
C. albicans
infection and vaginal
C. albicans
infection. This research may help us to investigate new antimicrobial agents for treating
C. albicans
infections.
Key Points
•
NEL can inhibit the growth of C. albicans.
•
NEL destroys the cell membrane formation and permeability of C. albicans.
•
NEL can treat vulvovaginal candidiasis and oropharyngeal candidiasis in mice.
•
NEL could be used as a possible antifungal agent.
DNA methylation is essential for epigenetic regulation of gene transcription and development in many animals, plants and fungi. We investigated whether DNA methylation plays a role in the development ...and secondary metabolism of Aspergillus flavus, identified the DmtA methyltransferase from A. flavus, and produced a dmtA knock-out mutant by replacing the dmtA coding sequence with the pyrG selectable marker. The A. flavus dmtA null mutant lines produced white fluffy mycelium in liquid medium, and displayed a slightly flavescent conidial pigmentation compared with the normal yellow of the wild-type strain when grown on agar. The ΔdmtA lines exhibited decreased conidiation and aflatoxin (AF) biosynthesis, compared with the wild-type line, suggesting that the DmtA knock-out affected the transcriptional level of genes in the AF cluster. In particular, sclerotia development and host colonization were altered in the dmtA null mutants. Green fluorescent protein tagging at the C-terminus of DmtA showed that DmtA localized to the nucleus and cytoplasm. DNA methylation content measurements in the dmtA mutants revealed no widespread DNA methylation in the mutants or wild-type lines. Thus, our findings suggest that DmtA, apart from being a C-5 cytosine methyltransferase in A. flavus, contributes to asexual development, aflatoxin biosynthesis, sclerotial production and virulence.
Aflatoxins (AFs) have always been regarded as the most effective carcinogens, posing a great threat to agriculture, food safety, and human health.
is the major producer of aflatoxin contamination in ...crops. The prevention and control of
and aflatoxin continues to be a global problem. In this study, we demonstrated that the cell-free culture filtrate of
and a non-aflatoxigenic
can effectively inhibit the production of AFB1 and the growth and reproduction of
, indicating that both of the non-aflatoxigenic
strains secrete inhibitory compounds. Further transcriptome sequencing was performed to analyze the inhibitory mechanism of
treated with fermenting cultures, and the results revealed that genes involved in the AF biosynthesis pathway and other biosynthetic gene clusters were significantly downregulated, which might be caused by the reduced expression of specific regulators, such as AflS, FarB, and MtfA. The WGCNA results further revealed that genes involved in the TCA cycle and glycolysis were potentially involved in aflatoxin biosynthesis. Our comparative transcriptomics also revealed that two conidia transcriptional factors,
and
, were found to be significantly downregulated, which might lead to the downregulation of conidiation-specific genes, such as the conidial hydrophobins genes
and
. In summary, our research provides new insights for the molecular mechanism of controlling AF synthesis to control the proliferation of
and AF pollution.
Histone acetyltransferases (HATs) help regulate fungal development and the production of secondary metabolites. In this study, we determined that the HAT AflGcnE influenced morphogenesis and ...aflatoxin biosynthesis in Aspergillus flavus. We observed that AflGcnE localized to the nucleus and cytoplasm during the conidial production and germination stages, while it was located mainly in the nucleus during the hyphal development stage. Deletion of AflgcnE inhibited the growth of A. flavus and decreased the hydrophobicity of the cell surface. The ΔAflgcnE mutant exhibited a lack of asexual sporulation and was unable to generate sclerotia. Additionally, AflgcnE was required to maintain cell wall integrity and genotoxic stress responses. Importantly, the ΔAflgcnE mutant did not produce aflatoxins, which was consistent with a significant down-regulation of aflatoxin gene expression levels. Furthermore, our data revealed that AflgcnE is a pathogenicity factor required for colonizing maize seeds. In summary, we revealed that A. flavus AflGcnE is crucial for morphological development, aflatoxin biosynthesis, stress responses, and pathogenicity. Our findings help clarify the functional divergence of GcnE orthologs, and may provide a possible target for controlling A. flavus infections of agriculturally important crops.
This study investigated the impact of dietary fiber from sweet potato residue (SPDF) on the diversity of the gut microbiota. An
in vitro
batch culture system simulating the human gut was used to ...understand the prebiotic role of SPDF. The results showed that SPDF mediated a significant increase in the concentrations of
Bifidobacterium
and
Lactobacillus
, whereas induced a significant decrease of
Enterobacillus
,
Clostridium perfringens
and
Bacteroides
. The prebiotic index and
Bifidobacterium
/
Enterobacillus
value were also significantly increased in SPDF groups compared to those of the control group, suggesting that SPDF had prebiotic effects. Furthermore, to investigate the effects of SPDF on the intestinal microecosystem, diets containing different concentrations of SPDF were used to feed Wistar rats for 4 weeks. 16S rRNA gene sequencing, short chain fatty acid quantification and physiochemical property analysis in the rat feces were then conducted. The results showed that SPDF significantly increased the
Bacteroidetes
to
Firmicutes
ratio at the phylum level and the amount of
Akkermansia
was also increased at the genus level, which was confirmed by qRT-PCR. The production of propionate and butyrate in the rat feces of both 3% and 15% SPDF groups was higher than that in the control group, which was further confirmed by the decrease of pH. Additionally, SPDF supplementation in this study resulted in a higher villus height to fossa depth ratio, which indicated improved digestion and absorption in the GI tract. Our findings support the utilization of SPDF from sweet potato residue in the development of potentially prebiotic food products for improving intestinal health.
This study investigated the impact of dietary fiber from sweet potato residue (SPDF) on the diversity of the gut microbiota.
Msb2 is important for growth, conidia and sclerotia formation in Aspergillus flavus. Msb2 play negative roles in regulation of aflatoxins biosynthesis.
Summary
As a pathogenic fungus, Aspergillus ...flavus can produce carcinogenic aflatoxins (AFs), which poses a great threat to crops and animals. Msb2, the signalling mucin protein, is a part of mitogen‐activated protein kinase (MAPK) pathway which contributes to a range of physiological processes. In this study, the roles of membrane mucin Msb2 were explored in A. flavus by the application of gene disruption. The deletion of msb2 gene (Δmsb2) caused defects in vegetative growth, sporulation and sclerotia formation when compared to WT and complement strain (Δmsb2C) in A. flavus. Using thin‐layer chromatography (TLC) and high‐performance liquid chromatography (HPLC) analysis, it was found that deletion of msb2 down‐regulated aflatoxin B1 (AFB1) synthesis and decreased the infection capacity of A. flavus. Consistently, Msb2 responds to cell wall stress and osmotic stress by positively regulating the phosphorylation of MAP kinase. Notably, Δmsb2 mutant exhibited cell wall defect, and it was more sensitive to inhibitor caspofungin when compared to WT and Δmsb2C. Taking together, these results revealed that Msb2 plays key roles in morphological development process, stresses adaptation, secondary metabolism and pathogenicity in fungus A. flavus.
Perillaldehyde (PAE), an essential oil in Perilla plants, serves as a safe flavor ingredient in foods, and shows an effectively antifungal activity. Reactive oxygen species (ROS) accumulation in
...plays a critical role in initiating a metacaspase-dependent apoptosis. However, the reason for ROS accumulation in
is not yet clear. Using transcriptome sequencing of
treated with different concentrations of PAE, our data showed that the ROS accumulation might have been as a result of an inhibition of energy metabolism with less production of reducing power. By means of GO and KEGG enrichment analysis, we screened four key pathways, which were divided into two distinct groups: a downregulated group that was made up of the glycolysis and pentose phosphate pathway, and an upregulated group that consisted of MAPK signaling pathway and GSH metabolism pathway. The inhibition of dehydrogenase gene expression in two glycometabolism pathways might play a crucial role in antifungal mechanism of PAE. Also, in our present study, we systematically showed a gene interaction network of how genes of four subsets are effected by PAE stress on glycometabolism, oxidant damage repair, and cell cycle control. This research may contribute to explaining an intrinsic antifungal mechanism of PAE against
.
, a ubiquitous filamentous fungus found in soil, plants and other substrates has been reported not only as a pathogen for plants, but also a carcinogen producing fungus for human. Peptidyl-Prolyl ...Isomerase (PPIases) plays an important role in cell process such as protein secretion cell cycle control and RNA processing. However, the function of PPIase has not yet been identified in
In this study, the PPIases gene from
named
was cloned into expression vector and the protein was expressed in prokaryotic expression system. Activity of recombinant ppci1 protein was particularly inhibited by FK506, CsA and rapamycin. 3D-Homology model of ppci1 has been constructed with the template, based on 59.7% amino acid similarity. The homologous recombination method was used to construct the single
gene deletion strain Δ
. We found that, the
gene plays important roles in
growth, conidiation, and sclerotia formation, all of which showed reduction in Δppci1 and increased in conidiation compared with the wild-type and complementary strains in
Furthermore, aflatoxin and peanut seeds infection assays indicated that
contributes to virulence of
Furthermore, we evaluated the effect of PPIase inhibitors on
growth, whereby these were used to treat wild-type strains. We found that the growths were inhibited under every inhibitor. All, these results may provide valuable information for designing inhibitors in the controlling infections of
.
PDF
