Echeveria
‘Perle von Nürnberg’ is a popular ornamental potted plant. In 2017–2018, stem rot lesions caused by
Fusarium
spp. were repeatedly observed on
Echeveria
‘Perle von Nürnberg’ in Zhangzhou, ...Fujian Province, China. In this study, samples were collected to isolate the pathogen. After morphological observations, molecular identification, and pathogenicity measurements, the pathogen was confirmed as
Fusarium oxysporum
. Green fluorescent protein was used to label
F. oxysporum
to observe the pathogenic process in the host plant. Two to three days after inoculation, the pathogen conidia adhered to the surface of the host stem and germinated into hyphae. The hyphae invaded the host cortex through wounds on the plant or the stem-leaf junction. The host stem produced greyish-brown circular or irregular lesions. Five days after inoculation, the expanded hyphae invaded the vascular cylinder and proliferated. The lesions on the host stem became larger and the neighboring leaves gradually fell off. Seven days after inoculation, the thalli continued to proliferate in the host, the hyphae continued to expand, and the host pith was damaged. The lesions on the stem continued to expand; the stems and branches became withered and lodged, and numerous leaves fell off. Given the rapid infection of
F. oxysporum
in
Echeveria
‘Perle von Nürnberg’ plants, necessary prevention and control measures should be employed prior to infection. In summary, this study demonstrated that the pathogen responsible for stem rot disease in
Echeveria
‘Perle von Nürnberg’ is
F. oxysporum
and further revealed the invasion modes and pathways of
F. oxysporum
in this plant, providing an empirical basis for the diagnosis and treatment of this stem rot pathogen.
Planococcus lilacinus (Cockerell) (Hemiptera: Pseudococcidae) is a global flower and fruit pest, and a severe infestation is currently seen in the sugar apple (Annona squamosa L., Annonaceae) ...orchards of Zhangzhou, Fujian Province, China. Biological control with entomopathogenic fungi is safe, effective, and long‐lasting, and has potential for the control of mealybugs. In this study, we analyzed the pathogenic characteristics and infection‐related genes of Metarhizium anisopliae (Metschn.) Sorokīn FM‐03, a strain discovered in the sugar apple orchards, against P. lilacinus, to evaluate its biocontrol potential and application prospects against mealybugs. The results showed that M. anisopliae FM‐03 was highly pathogenic against P. lilacinus. At 10 days after infection, the median lethal concentration (LC50) of strain FM‐03 was 1.45 × 105 spores ml−1 and the cumulative corrected mortality was 93%, whereas the median lethal time (LT50) was 5.27 days for treatment with the highest spore concentration (108 spores ml−1). Planococcus lilacinus was primarily infected from the legs, abdominal segments, and body edges, which are sites with less wax. Infection became clearly visible 72 h post inoculation. Substantial changes occurred in activity of fungal enzymes, with peak values of 26 U ml−1 for proteases and 17 U ml−1 for lipases on day 5 post inoculation to enzyme inducing culture media. The activity of chitinases was relatively stable, with a peak value of 8 U ml−1 on day 6 post inoculation. At 3 days post P. lilacinus infection, a total of 1 069 genes were differentially expressed, of which 137 were annotated as infection‐related. Among the 136 upregulated genes, 10 were identified as potentially crucial for infection regulation. These 10 genes could be targeted for subsequent construction of genetically engineered FM‐03 strains, driving the research and development of effective biocontrol agents for P. lilacinus.
Planococcus lilacinus (Hemiptera: Pseudococcidae) is a quarantine pest in China. Entomopathogenic fungi could provide sustainable control. We studied the efficacy of Metarhizium anisopliae strain FM‐03 against P. lilacinus. The fungus was highly pathogenic, killing up to 93% of the insects. The strain secretes proteinase, chitinase, and lipase enzymes to degrade the mealybug cuticle. Ten genes were identified as potentially critical for infection. These results will aid the development of effective biocontrol agents for P. lilacinus.
Anthracnose of guava, caused by the fungus Colletotrichum gloeosporioides, is a major factor limiting worldwide guava production. Timely and accurate detection of the pathogen is important in ...developing a disease management strategy. Herein, a loop-mediated isothermal amplification (LAMP) assay for the specific and sensitive detection of C. gloeosporioides was developed using primers targeting the β-tubulin 2 (TUB2) gene. The optimal reaction conditions were 64 °C for 60 min. The specificity of the method was tested against C. gloeosporioides isolates, Colletotrichum spp. isolates, and isolates of other genera. Positive results were obtained only in the presence of C. gloeosporioides, whereas no cross-reaction was observed for other species. The detection limit of the LAMP assay was 10 fg of genomic DNA in a 25 μL reaction. The LAMP assay successfully detected C. gloeosporioides in guava fruit collected in the field. The results indicate that the developed LAMP assay is a simple, cost-effective, rapid, highly sensitive, and specific tool for the diagnosis of guava anthracnose caused by C. gloeosporioides and could be useful for disease management.
Zhangzhou in Fujian province is the primary habitat for the succulent plant
Echeveria
‘Perle von Nürnberg’ (Crassulaceae), which has seriously suffered from anthracnose disease in recent years. ...Plants with typical disease symptoms were collected from three planting bases in Zhangzhou, and pathogens were isolated for further identification. The pathogen was identified as
Colletotrichum destructivum
by morphological observation, rDNA-ITS, Actin, and TUB2 gene sequence analysis, and pathogenicity identification. This is the first ever report of anthracnose caused by
C. destructivum
on
Echeveria
‘Perle von Nürnberg.’
Colletotrichum gloeosporionides
is the causative agent of a major disease affecting
Psidium guajava
fruits from fructescence to post-harvest. A polymerase chain reaction (PCR)-based method for the ...detection of
C. gloeosporioides
was developed in this study. A set of two primers (CGF and CGR) specific for
C. gloeosporioides
were designed based on the sequences of the ribosomal internal transcribed spacer (ITS) regions. The specificity of primers was analyzed by the absence of amplified product with DNA of tested isolates. The designed primers amplified a single product of ~390 bp with DNA extracted from isolates of
C. gloeosporioides,
and did not amplify DNA from several
Colletotrichum
species and other different fungal genera. The sensitivity of conventional PCR was 10 pg purified genomic DNA in 25 μL reaction. A nested PCR system was established to combine specific and universal ITS primers (ITS1/ITS4), and this enhanced the sensitivity to 1 fg of DNA per 25 μL reaction, representing a 10,000-fold improvement over conventional PCR. The optimised reaction system could detect
C. gloeosporionides
successfully from diseased plant tissue, infected soil and water. The developed system can detect
C. gloeosporioides
during the early stages of disease onset and provide evidence to guide management and decision-making.
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•Immunity of thrips decreased in lower latitudes in China.•Immunity response was lower at latitudes with higher degree days.•Expression of key toll pathway genes significantly ...increased at higher latitudes.
Gynaikothrips uzeli gall thrips are protected from insecticide exposure by their leaf gall habitat. A biocontrol strategy based on entomopathogenic fungi is an alternative approach for the control of G. uzeli. Higher temperatures can promote the reproduction and spread of pests; however, the impact of higher temperatures on biological control is unclear. We studied the immunocompetence of thrips from different latitudes and determined the effect of degree days on thrips immunity. We examined the potential impact of temperature on the biocontrol provided by entomopathogenic fungi. Beauveria bassiana pathogenicity against thrips increased with decreasing latitude, suggesting that immunity of thrips increased as latitude increased. The phenoloxidase activity of G. uzeli increased with increasing latitude but there was no significant change in hemocyte concentration. This indicated that the humoral immunity of thrips was significantly associated with degree days, and this was confirmed by transcriptome data. Transcriptome and RT-PCR results showed that the expression of key genes in eight toll pathways increased with increasing latitude. The relative expression of key genes in the Toll pathway of thrips and the activity of phenoloxidase decreased with increasing degree days that are characteristic of lower latitudes. These changes led to a decrease in humoral immunity. The immunity of G. uzeli against entomopathogenic fungi increased as degree days characteristic of lower latitudes decreased. Increased temperatures associated with lower latitude may therefore increase biocontrol efficacy. This study clarified immune level changes and molecular mechanisms of thrips under different degree days.
Anthracnose of guava, caused by the fungus Colletotrichum gloeosporioides, is a major factor limiting worldwide guava production. Timely and accurate detection of the pathogen is important in ...developing a disease management strategy. Herein, a loop-mediated isothermal amplification (LAMP) assay for the specific and sensitive detection of C. gloeosporioides was developed using primers targeting the beta-tubulin 2 (TUB2) gene. The optimal reaction conditions were 64 degreesC for 60 min. The specificity of the method was tested against C. gloeosporioides isolates, Colletotrichum spp. isolates, and isolates of other genera. Positive results were obtained only in the presence of C. gloeosporioides, whereas no cross-reaction was observed for other species. The detection limit of the LAMP assay was 10 fg of genomic DNA in a 25 microL reaction. The LAMP assay successfully detected C. gloeosporioides in guava fruit collected in the field. The results indicate that the developed LAMP assay is a simple, cost-effective, rapid, highly sensitive, and specific tool for the diagnosis of guava anthracnose caused by C. gloeosporioides and could be useful for disease management.
Fusarium wilt, caused by
Fusarium oxysporum
f. sp.
cucumerinum
Owen (FOC), is a destructive disease affecting cucumber production worldwide. Developing an accurate and reliable method for detection ...of FOC is important for disease prediction and control. In this study, a loop-mediated isothermal amplification (LAMP) assay was developed and validated for specific and sensitive detection of FOC. Four LAMP primers were designed based on the sequence of the FOC-specific random amplified polymorphic DNA (RAPD) marker OPZ-12
865
. LAMP reactions were performed at different temperatures and for different durations, and the optimal temperature and duration were 63 °C for 60 min, respectively. Hence, a LAMP assay for detection of FOC was established. The specificity of the LAMP method was evaluated against 119 isolates of FOC and other pathogens, and only FOC isolates yielded positive results. In sensitivity tests, the lowest concentration of genomic DNA required for the LAMP assay was 10 fg in a 25 μL reaction. The LAMP assay was successfully applied to detect FOC in cucumber tissues and soil from infested fields, and the positive ratios of LAMP, PCR, and traditional tissue isolation for detecting FOC from diseased cucumber root samples were100%, 86.6 and 83.3%, respectively. Therefore, the LAMP assay developed herein should serve as a simple, cost-effective, rapid, highly specific, and sensitive tool for the visual detection of FOC and contribute to improved disease management.
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